Universal cervical length screening and risk of spontaneous preterm birth: a systematic review and meta-analysis

OBJECTIVE

To evaluate the risk of spontaneous preterm birth with or without universal transvaginal ultrasound cervical length screening at the time of midtrimester scan.

DATA SOURCES

Medline, Embase, ClinicalTrials.gov, and Web of Science were systematically searched from the inception of the databases to November 12, 2023, using combinations of the relevant medical subject heading terms, key words, and word variants that were considered suitable for the topic.

STUDY ELIGIBILITY CRITERIA

Studies including individuals with singleton gestations at 16-25 weeks of gestation screened or not screened with universal transvaginal ultrasound cervical length screening were considered eligible. Primary outcome was spontaneous preterm birth <37 weeks; secondary outcomes were spontaneous preterm birth <34 and <32 weeks.

METHODS

Random effect head-to-head analyses were used to directly compare each outcome, expressing the results as summary odds ratio and relative 95% confidence interval. The quality of the included studies was independently assessed by 2 reviewers, using the Newcastle-Ottawa scale for cohort studies and the Cochrane risk-of-bias tool for randomized controlled studies. The study was registered on the prospective register of systematic reviews database (PROSPERO) (registration number: CRD42022385325).

RESULTS

Eight studies, including 447,864 pregnancies, were included in the meta-analysis (213,064 screened with transvaginal ultrasound cervical length and 234,800 unscreened). In the overall analysis, universal transvaginal ultrasound cervical length did not significantly decrease the spontaneous preterm birth rates <37 weeks (odds ratio, 0.92 [95% confidence interval, 0.84-1.01], P=.07) and <34 weeks (odds ratio, 0.87 [95% confidence interval, 0.73-1.04], P=.12), but was significantly associated with a lower risk of spontaneous preterm birth <32 weeks (odds ratio, 0.84 [95% confidence interval, 0.76-0.94], P=.002). Individuals without a prior spontaneous preterm birth had a significantly lower risk of spontaneous preterm birth <37 weeks (odds ratio, 0.88 [95% confidence interval, 0.79-0.97], P=.01) and a lower trend of spontaneous preterm birth <32 weeks (odds ratio, 0.82 [95% confidence interval, 0.66-1.01], P=.06) when screened with transvaginal ultrasound cervical length, compared with no screening.

CONCLUSION

Universal transvaginal ultrasound cervical length screening usually <24 weeks in singletons without a prior spontaneous preterm birth, is associated with a significant reduction in spontaneous preterm birth <37 weeks, compared with no screening.

Vaginal Progesterone to Prevent Spontaneous Preterm Birth in Women With a Sonographic Short Cervix: The Story of the PREGNANT Trial

The PREGNANT trial was a randomized, placebo-controlled, multicenter trial designed to determine the efficacy and safety of vaginal progesterone (VP) to reduce the risk of birth <33 weeks and of neonatal complications in women with a sonographic short cervix (10 to 20 mm) in the mid-trimester (19 to 23 6/7 wk). Patients allocated to receive VP had a 45% lower rate of preterm birth (8.9% vs 16.1%; relative risk = 0.55; 95% CI: 0.33-0.92). Neonates born to mothers allocated to VP had a 60% reduction in the rate of respiratory distress syndrome. This article reviews the background, design, execution, interpretation, and impact of the PREGNANT Trial.

Effects of vaginal progesterone and placebo on preterm birth and antenatal outcomes in women with singleton pregnancies and short cervix on ultrasound: a meta-analysis

Background

Vaginal progesterone in preterm birth and adverse outcomes caused by cervical insufficiency remains controversial. To address it, the effect of vaginal progesterone on preterm delivery and perinatal outcome of single pregnancy women with short cervix (less than 25 mm) was systematically evaluated by meta-analysis.

Methods

"Vaginal progesterone," "placebo," "ultrasound," "cervix," "singleton pregnancy," "preterm birth," and "antenatal outcomes" were entered to screen clinical studies PubMed, Embase, and the Chinese Biomedical Literature Database (CBM). The study population consisted of women with singleton pregnancies and a short cervix on ultrasound, and were assigned into the progesterone group (n = 1,368) and the placebo group (n = 1,373). Treatment began after the patient was diagnosed with short cervix until delivery. Neonatal survival rate, Neonatal Intensive Care Unit (NICU) admission rate, respiratory distress syndrome (RDS), intraventricular hemorrhage (IVH), neonatal mortality, and birth weight <1,500 g were analyzed.

Results

A total of 8 articles, totaling 2,741 study subjects, were enrolled. The progesterone group exhibited an obvious reduced rate of preterm birth at <34 weeks (OR = 0.67, 95% CI: 0.53∼0.84; Z = 3.53, P = 0.004), preterm birth at <32 weeks (OR = 0.46, 95% CI: 0.28∼0.77; Z = 2.99, P = 0.003), NICU admission rate (OR = 0.45, 95% CI: 0.30∼0.66; Z = 0.15, P < 0.0001), RDS rate (OR = 0.42, 95% CI: 0.28∼0.63; Z = 4.25, P < 0.0001), IVH incidence rate (OR = 0.40, 95% CI: 0.17∼0.95; Z = 2.08, P = 0.04), neonatal mortality (OR = 0.25, 95% CI: 0.13∼0.46; Z = 4.39, P < 0.0001), and proportion of neonates with birth weight < 1,500 g (OR = 0.45, 95% CI: 0.32∼0.64; Z = 4.50, P < 0.0001).

Conclusion

Vaginal progesterone lowered the incidences of preterm birth and adverse pregnancy outcomes in women with singleton pregnancies and a short cervix.

Transvaginal cerclage for prevention of preterm birth in twin pregnancies with cervical dilatation or shortening: A prospective observational study

OBJECTIVE

To investigate the efficacy of transvaginal cerclage in twin pregnancies with cervical shortening, and to narrow the threshold cervical length for transvaginal cerclage.

METHODS

This is a prospective cohort study and 177 twin pregnancies with asymptomatic cervical dilatation or cervical length of 15 mm or less between 16+0 and 25+6 weeks of pregnancy were included. Patients independently chose either transvaginal cerclage (n = 129) or no cerclage treatment (n = 48) after being consulted on the risk and potential benefit of transvaginal cerclage. The primary outcome measures were gestational age at delivery and neonatal survival rate.

RESULTS

Compared with the no cerclage group, the cerclage group exhibited a higher gestational age at delivery (32.1 ± 4.5 vs 28.3 ± 6.2 weeks, P < 0.001) and a higher neonatal survival rate (86.4% vs 47.9%, P < 0.001). Subgroup analysis showed that in twin pregnancies with cervical dilatation or cervical length less than 10 mm, the cerclage group had significantly higher gestational age at delivery (31.3 ± 4.6 vs 23.4 ± 4.3 weeks, P < 0.001) and a higher neonatal survival rate (123 [85.4%] vs 4 [9.1%], P < 0.001) than the no cerclage group, but in twins when cervical length was 10-15 mm, the two measures were similar between the two groups.

CONCLUSION

Transvaginal cerclage may provide benefits for twins when cervical dilatation or cervical length is less than 10 mm, but its efficacy might not extend to twins when the cervical length is 10-15 mm. Further evidence is needed to confirm the efficacy of transvaginal cerclage for twin pregnancies with a short cervix.

Cervical assessment certification and its impact on performance quality in the context of universal cervical screening

OBJECTIVE

To assess the impact of the introduction of universal transvaginal cervical screening and certification on the quality of cervical length ultrasound images.

METHODS

The present study included a retrospective cohort of singleton pregnancies that underwent transvaginal cervical length measurement at the anatomical scan (180/7 and 236/7 weeks) before (period A, 2015-2017) and after (period B, 2017-2019) the introduction of universal transvaginal cervical length screening. Independent observers blindly evaluated the images obtained for cervical length using a qualitative scoring method based on five criteria, according to the Fetal Medicine Foundation.

RESULTS

In all, 6013 patients met the inclusion criteria, 3333 in period A and 2680 in period B. Maternal characteristics and risk factors for preterm birth were similar between the two periods. The acceptance of transvaginal cervical length measurement in period B was 95.5% in the overall cohort and 100% in the subgroup of high-risk patients. The quality score was significantly higher in period B than in period A. Among the image quality criteria, the anterior/posterior ratio, the correct magnification of the images, and the calipers' placement contributed significantly to the improved quality score in period B. Most of the sonographers performed better in period B, irrespective of the years of experience, but certificate holders obtained higher scores than non-certified sonographers, particularly those in mid-career. The identification of short cervix was significantly higher in period B than in period A.

CONCLUSION

The implementation of universal transvaginal cervical length screening and the certification process are associated with improved quality of cervical length images, even among expert sonographers and in the presence of anatomical pitfalls.

Management of short cervix in twin-to-twin transfusion syndrome: a role for pessary placement following fetoscopic laser surgery?

BACKGROUND

Preterm labor and delivery is a major concern for patients with twin-to-twin transfusion syndrome undergoing fetoscopic laser surgery. A preoperative short cervix is a risk factor for preterm labor. Pessary placement is a short-acting intervention that may be useful to reduce this adverse event.

OBJECTIVE

This study aimed to investigate the relationship between pessary placement and preterm delivery in monochorionic twin pregnancies with twin-to-twin transfusion syndrome and a short cervix before fetoscopic laser surgery.

STUDY DESIGN

This was a retrospective study in 2 centers, including all pregnancies affected by twin-to-twin transfusion syndrome that underwent fetoscopic laser surgery with the Solomon technique between 2013 and 2022 (center A) and 2014 and 2022 (center B) with a preoperative cervical length below 25 mm. This study explored the correlation between cervical length and fetoscopic laser surgery-to-delivery interval following active or expectant management and compared perinatal outcomes between patients managed expectantly and patients managed with pessary placement, using multivariate analysis to control for potential confounders. Patients with a cervical length below 5 mm were not included in the comparative analysis.

RESULTS

Of 685 patients, 134 met the inclusion criteria. Moreover, 21 patients were treated with a cervical cerclage and excluded from the analysis, leaving 113 patients for the final analysis. There was a significant negative correlation between cervical length at fetoscopic laser surgery and the risk of early delivery (adjusted odds ratio, 0.66; 95% confidence interval, 0.49-0.81; P<.001). The use of a pessary correlated with fewer patients delivering before 28 weeks of gestation (adjusted odds ratio, 0.28; 95% confidence interval, 0.09-0.75), fewer double neonatal demise (adjusted odds ratio, 0.2; 95% confidence interval, 0.05-0.75). Posthoc subgroup analysis suggested that these improvements were essentially noticeable for cervical lengths between 5 and 18 mm, where pessary placement was associated with an increased fetoscopic laser surgery-to-delivery interval (+24 days; 95% confidence interval, 0.86-42; P=.042) and later gestational age at delivery (+3.3 weeks; 95% confidence interval, 0.86-42; P=.035).

CONCLUSION

Patients with a moderately shortened cervix, between 5 and 18 mm, may benefit from pessary placement after fetoscopic surgery for twin-to-twin transfusion syndrome, resulting in a reduction of adverse neonatal outcomes, double neonatal demise, and severe preterm delivery.

PROMPT: Prospective Meta-analysis for Pessary Trials Study Protocol

OBJECTIVE

 Preterm birth, defined as birth before 37 weeks of gestation, is a leading cause of perinatal and infant mortality throughout the world. Preterm birth is also associated with long-term neurological disabilities and other significant health issues in children. A short cervix in the second trimester has been noted to be one of the strongest predictors of subsequent spontaneous preterm birth in both singleton and multiple pregnancies. Some studies have shown that cervical support in the form of an Arabin pessary lowers the risk of preterm birth in women with a singleton gestation and short cervical length; however, other studies have conflicting results. Our objective was to form an international collaborative of planned or ongoing randomized trials of pessary in singleton and twin gestations with a short cervix.

STUDY DESIGN

 In November 2014, an international group of investigators, who had initiated or were planning randomized trials of pessary for pregnant people with a short cervix and singleton or twin gestation to prevent preterm birth, formed a collaboration to plan a prospective individual patient data (IPD) meta-analysis of randomized trials (PROspective Meta-analysis of Pessary Trials [PROMPT]). The PROMPT investigators agreed on meta-analysis IPD hypotheses for singletons and twins, eligibility criteria, and a set of core baseline and outcome measures. The primary outcome is a composite of fetal death or preterm delivery before 32 weeks' gestation. Secondary outcomes include maternal and neonatal morbidities. The PROMPT protocol may be viewed as a written agreement among the study investigators who make up the PROMPT consortium (PROSPERO ID# CRD42018067740).

RESULTS

 Results will be published in phases as the individual participating studies are concluded and published. Results of the first phase of singleton and twin pessary trials are expected to be available in late 2022. Updates are planned as participating trials are completed and published.

KEY POINTS

· Short cervical length predicts preterm birth.. · Results of prior cervical pessary trials are mixed.. · Meta-analysis of pessary trials protocol..

Relationship between plasma concentration of 17-hydroxyprogesterone caproate and gestational age at preterm delivery

BACKGROUND

The effectiveness of 17-hydroxyprogesterone caproate is unclear as trials have provided conflicting results. With the absence of fundamental pharmacologic studies addressing dosing or the relationship between drug concentration and gestational age at delivery, the effectiveness of the medication cannot be evaluated.

OBJECTIVE

This study aimed to evaluate the relationship between plasma concentrations of 17-hydroxyprogesterone caproate and preterm birth rates and gestational age at preterm delivery and to assess the safety of the 500-mg dose.

STUDY DESIGN

This study recruited 2 cohorts with previous spontaneous preterm birth; 1 cohort (n=143) was randomly assigned to either 250-mg or 500-mg 17-hydroxyprogesterone caproate, and the other cohort (n=16) was receiving the 250-mg dose for routine care. Steady-state trough plasma concentrations of 17-hydroxyprogesterone caproate obtained at 26 to 30 weeks of gestation were correlated to dose, spontaneous preterm birth rates, and measures of gestational length. Furthermore, maternal and neonatal safety outcomes were evaluated according to dose.

RESULTS

There was a dose proportional increase in trough plasma concentrations with the 250-mg (median, 8.6 ng/m; n=66) and 500-mg (median, 16.2 ng/mL; n=55) doses. In 116 compliant participants with blood samples, drug concentration was not related to the spontaneous preterm birth rate (odds ratio, 1.00; 95% confidence interval, 0.93-1.08). However, there was a significant relationship between drug concentration and both the interval from the first administration to delivery (interval A: coefficient, 1.11; 95% confidence interval, 0.00-2.23; P=.05) and the interval from the 26- to 30-week blood draw to delivery (interval B: coefficient, 1.56; 95% confidence interval, 0.25-2.87; P=.02). The spontaneous preterm birth rate or measures of gestational length were not related to dose. Postenrollment cerclage adversely affected all pharmacodynamic assessments because it was a powerful predictor of spontaneous preterm birth (odds ratio, 4.03; 95% confidence interval, 1.24-13.19; P=.021) and both measures of gestational length (interval A [coefficient, -14.9; 95% confidence interval, -26.3 to -3.4; P=.011] and interval B [coefficient, -15.9; 95% confidence interval, -25.8 to -5.9; P=.002]). Initial cervical length was significantly related to the risk of postenrollment cerclage (odds ratio, 0.80; 95% confidence interval, 0.70-0.92; P=.001). Maternal and neonatal safety outcomes were similar in both dosing groups.

CONCLUSION

In this pharmacodynamic study, trough plasma 17-hydroxyprogesterone caproate concentrations were significantly associated with gestational age at preterm birth but not with the preterm birth rate. Postenrollment cerclage was a powerful predictor of spontaneous preterm birth rate and gestational length. Initial cervical length predicted the risk of postenrollment cerclage. Adverse events were similar with the 500-mg and 250-mg doses of 17-hydroxyprogesterone caproate.

The exciting potential for ChatGPT in obstetrics and gynecology

Natural language processing-the branch of artificial intelligence concerned with the interaction between computers and human language-has advanced markedly in recent years with the introduction of sophisticated deep-learning models. Improved performance in natural language processing tasks, such as text and speech processing, have fueled impressive demonstrations of these models' capabilities. Perhaps no demonstration has been more impactful to date than the introduction of the publicly available online chatbot ChatGPT in November 2022 by OpenAI, which is based on a natural language processing model known as a Generative Pretrained Transformer. Through a series of questions posed by the authors about obstetrics and gynecology to ChatGPT as prompts, we evaluated the model's ability to handle clinical-related queries. Its answers demonstrated that in its current form, ChatGPT can be valuable for users who want preliminary information about virtually any topic in the field. Because its educational role is still being defined, we must recognize its limitations. Although answers were generally eloquent, informed, and lacked a significant degree of mistakes or misinformation, we also observed evidence of its weaknesses. A significant drawback is that the data on which the model has been trained are apparently not readily updated. The specific model that was assessed here, seems to not reliably (if at all) source data from after 2021. Users of ChatGPT who expect data to be more up to date need to be aware of this drawback. An inability to cite sources or to truly understand what the user is asking suggests that it has the capability to mislead. Responsible use of models like ChatGPT will be important for ensuring that they work to help but not harm users seeking information on obstetrics and gynecology.

Different effects for different questions: An illustration using short cervix and the risk of preterm birth

OBJECTIVE

To illustrate the difference between exposure effects and population attributable effects.

METHODS

We examined the effect of mid-pregnancy short cervical length (<25 mm) on preterm birth using data from a prospective cohort of pregnant women in Lusaka, Zambia. Preterm birth was live birth or stillbirth before 37 weeks of pregnancy. For estimation, we used multivariable regression and parametric g-computation.

RESULTS

Among 1409 women included in the analysis, short cervix was rare (2.4%); 13.6% of births were preterm. Exposure effect estimates were large (marginal risk ratio 2.86, 95% confidence interval [CI] 1.80-4.54), indicating that the preterm birth risk was substantially higher among women with a short cervix compared with women without a short cervix. However, the population attributable effect estimates were close to the null (risk ratio 1.06, 95% CI 1.02-1.10), indicating that an intervention to counteract the impact of short cervix on preterm birth would have minimal effect on the population risk of preterm birth.

CONCLUSION

Although authors often refer to "the" effect, there are actually different types of effects, as we have illustrated here. In planning research, it is important to consider which effect to estimate to ensure that the estimate aligns with the research objective.

The introduction of a universal transvaginal cervical length screening program is associated with a reduced preterm birth rate

BACKGROUND

Midtrimester sonographic short cervix is a good predictor of preterm birth in singleton pregnancies.

OBJECTIVE

This study aimed to assess the impact of implementing a universal transvaginal cervical length screening program on preterm birth rate.

STUDY DESIGN

This study consisted of 2 parts: a before-and-after multicenter study and a study on the ECHOCOL ("echo"="ultrasound" and "col"="cervix" in French) prospective cohort. We compared the rate of preterm birth before and after the introduction of universal cervical length screening at the time of midtrimester anatomy ultrasound. The multicenter before-and-after regional study included all women with a singleton pregnancy who gave birth after 24 weeks' gestation in the South East of France from January 1, 2012 to April 30, 2018. In parallel, the ECHOCOL cohort study was prospectively conducted from May 2015 to July 2018, including 17 maternity hospitals in the South East region of France. In case of asymptomatic short cervix <25 mm, treatments offered included 200 mg of vaginal progesterone, or cerclage, or a pessary until 34 weeks' gestation.

RESULTS

We observed a significant decrease rate of preterm birth between periods A and B after multivariate analysis. (respectively, 5.8% vs 5.6%; adjusted odds ratio, 0.92; 95% confidence interval, 0.89-0.95; P<.0001). In parallel, the percentage of cervical length screening significantly increased from 28.9% in period A to 52.9% in period B (odds ratio, 2.76; 95% confidence interval, 2.71-2.80; P<.0001). Among the 3468 patients of the ECHOCOL prospective cohort, 38 (1.1%) asymptomatic short cervices were detected, and 192 patients gave birth prematurely (11 with an asymptomatic short cervix and 181 without). In the ECHOCOL cohort, a marked but statistically insignificant tendency toward a reduced rate of preterm birth before 37 weeks of gestation was observed (from 5.8% to 5.5%; adjusted odds ratio, 0.72; 95% confidence interval, 0.51-1.03; P=.068).

CONCLUSION

This study showed a significantly lower rate of preterm birth after the implementation of a universal cervical length screening and treating policy during the second trimester of pregnancy. The clinical trial was registered under NCT02598323.

Vaginal progesterone for the prevention of preterm birth: who can benefit and who cannot? Evidence-based recommendations for clinical use

Vaginal progesterone (VP) has been recommended to prevent preterm birth (PTB) in women at high-risk. However, there is controversy as to whether VP is efficacious in some subsets of high-risk women. In this review, we examined the current best evidence on the efficacy of VP to prevent PTB in several subsets of high-risk women and provided recommendations for its clinical use. Compelling evidence indicates that VP reduces the risk of PTB and improves perinatal outcomes in singleton gestations with a short cervix (≤25 mm), both with and without a history of spontaneous PTB. VP appears promising to reduce the risk of PTB in twin gestations with a short cervix (≤25 mm) and in singleton gestations conceived by assisted reproductive technologies, but further research is needed. There is no convincing evidence that supports prescribing VP to prevent PTB in singleton gestations based solely on the history of spontaneous preterm birth. Persuasive evidence shows that VP does not prevent PTB nor does it improve perinatal outcomes in unselected twin gestations and in singleton gestations with a history of spontaneous PTB and a cervical length >25 mm. There is no evidence supporting the use of VP to prevent PTB in triplet or higher-order multifetal gestations, singleton gestations with a positive fetal fibronectin test and clinical risk factors for PTB, and gestations with congenital uterine anomalies or uterine leiomyoma. In conclusion, current evidence indicates that VP should only be recommended in singleton gestations with a short cervix, regardless of the history of spontaneous PTB.

The effectiveness of vaginal progesterone in reducing preterm birth in high-risk patients diagnosed with short cervical length after 24 weeks: A retrospective cohort study

Objective

To assess the impact of progesterone treatment on maternal and neonatal outcomes in women with a history of preterm birth and short cervical length diagnosed after 24 weeks of gestation.

Methods

A retrospective cohort study included women with a history of preterm birth and a transvaginal sonographic cervical length measurement of ≤ 25 mm, diagnosed between 24⁺⁰ and 33⁺⁶ weeks of gestation. Exclusion criteria included prior progesterone treatment, cervical cerclage, or pessary. The study population was divided into the progesterone treatment group and the non-treatment group.

Results

The study included 104 women, with 46.2% (48/104) receiving progesterone treatment and 53.8% (56/104) not receiving treatment. The rate of spontaneous preterm birth before 37 weeks of gestation was 43% (24/56) in the non-treatment group and 31% (15/48) in the progesterone treatment group (P = 0.14); the rate of spontaneous preterm birth before 34 weeks was 7% (4/56) in the non-treatment group and 0% (0/48) in the progesterone treatment group (P = 0.05). Progesterone treatment was associated with a significant decrease in neonatal intensive care unit admissions (OR 0.20, 95% CI 0.05-0.74) and in the neonatal hospitalization period (mean difference in days 2.43, 95% CI 0.44-4.42). The risk of recurrent spontaneous preterm birth was highest (71%) among women with two or more previous preterm deliveries who did not receive progesterone treatment, and lowest (24%) among women with one previous preterm delivery who received progesterone treatment.

Conclusion

Progesterone treatment was associated with a reduction in rates of spontaneous preterm birth before 34 weeks of gestation, neonatal intensive care unit admission, and neonatal length of stay in high-risk patients, even when initiated after 24 weeks of gestation.

Effect of preoperative low-normal cervical length on perinatal outcome after laparotomy-assisted fetoscopic spina bifida repair

OBJECTIVE

To determine if preoperative cervical length in the low-normal range increases the risk of adverse perinatal outcome in patients undergoing fetoscopic spina bifida repair.

METHODS

This was a retrospective cohort study of patients who underwent fetal spina bifida repair between September 2014 and May 2022 at a single center. Cervical length was measured on transvaginal ultrasound during the week before surgery. Eligibility for laparotomy-assisted fetoscopic spina bifida repair was as per the criteria of the Management of Myelomeningocele Study, although maternal body mass index (BMI) up to 40 kg/m² was allowed. Laparotomy-assisted fetoscopic spina bifida repair was performed, with carbon dioxide insufflation via two 12-French ports in the exteriorized uterus. All patients received the same peri- and postoperative tocolysis regimen, including magnesium sulfate, nifedipine and indomethacin. Postoperative follow-up ultrasound scans were performed either weekly (< 32 weeks' gestation) or twice a week (≥ 32 weeks). Perinatal outcome was compared between patients with a preoperative cervical length of 25-30 mm vs those with a cervical length > 30 mm. Logistic regression analyses and generalized linear mixed regression analyses were used to predict delivery at less than 30, 34 and 37 weeks' gestation.

RESULTS

The study included 99 patients with a preoperative cervical length > 30 mm and 12 patients with a cervix 25-30 mm in length. One further case which underwent spina bifida repair was excluded because cervical length was measured > 1 week before surgery. No differences in maternal demographics, gestational age (GA) at surgery, duration of surgery or duration of carbon dioxide uterine insufflation were observed between groups. Cases with low-normal cervical length had an earlier GA at delivery (median (range), 35.2 (25.1-39.7) weeks vs 38.2 (26.0-40.9) weeks; P = 0.01), higher rates of delivery at < 34 weeks (41.7% vs 10.2%; P = 0.01) and < 30 weeks (25.0% vs 1.0%; P < 0.01) and a higher rate of preterm prelabor rupture of membranes (PPROM) (58.3% vs 26.3%; P = 0.04) at an earlier GA (mean ± SD, 29.3 ± 4.0 weeks vs 33.0 ± 2.4 weeks; P = 0.05) compared to those with a normal cervical length. Neonates of cases with low-normal cervical length had a longer stay in the neonatal intensive care unit (20 (7-162) days vs 9 (3-253) days; P = 0.02) and higher rates of respiratory distress syndrome (50.0% vs 14.4%; P < 0.01), sepsis (16.7% vs 1.0%; P = 0.03), necrotizing enterocolitis (16.7% vs 0%; P = 0.01) and retinopathy (33.3% vs 1.0%; P < 0.01). There was an association between preoperative cervical length and risk of delivery at < 30 weeks which was significant only for patients with a maternal BMI < 25 kg/m² (odds ratio, 0.37 (95% CI, 0.07-0.81); P = 0.02).

CONCLUSIONS

Low-normal cervical length (25-30 mm) as measured before in-utero laparotomy-assisted fetoscopic spina bifida repair may increase the risk of adverse perinatal outcomes, including PPROM and preterm birth, leading to higher rates of neonatal complications. These data warrant further research and are of critical relevance for clinical teams considering the eligibility of patients for in-utero spina bifida repair. Based on this evidence, patients with a low-normal cervical length should be aware of their increased risk for adverse perinatal outcome. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Proposed staging criteria for sonographic and physical exam for cervical changes at <24 weeks gestation to predict preterm birth

Asymptomatic cervical changes, such as cervical length shortening and dilation, which often occur before spontaneous preterm birth, have been described well in singleton pregnancies with or without history of preterm birth. The current screening strategies available to identify patients at increased risk of spontaneous preterm birth include use of transvaginal ultrasound for cervical length assessment and for detection of a short cervical length (≤25 mm) before 24 weeks of gestation. Whether an additional evaluation of the cervix (ie, via speculum or manual exam) is indicated is often pondered by clinicians and may depend on how short the cervical length is and if there is a history of preterm birth. Based on expert opinion, we developed a novel staging system of asymptomatic cervical changes including the following: cervical length measurement, cervical and membrane appearance on speculum exam, and cervical dilation by manual exam. This staging system, if proven accurate, may aid in standardizing definitions for purposes of patient prognosis, evaluation of intervention efficacy, and clinical management.

Resolution of acute cervical insufficiency after antibiotics in a case with amniotic fluid sludge

Cervical insufficiency generally refers to a condition in which there is mid-trimester cervical dilatation or protruding chorioamniotic membranes in the absence of uterine contractions. Such condition is a risk factor for spontaneous mid-trimester abortion or early preterm birth, and is associated with adverse neonatal outcomes. Both intra-amniotic infection and inflammation ascertained by amniocentesis have been identified in patients with cervical insufficiency, and are poor prognostic factors. A subset of patients with intra-amniotic inflammation will have no demonstrable microorganisms detected via cultivation or molecular methods, and therefore represent cases of sterile intra-amniotic inflammation. Amniotic fluid sludge (free-floating hyperechogenic material within the amniotic fluid in close proximity to the uterine cervix) identified on sonography is a biomarker for intra-amniotic infection and inflammation. Recent evidence suggests that intra-amniotic infection, as well as sterile intra-amniotic inflammation can be treated successfully using antimicrobial agents. We report a unique case in which administration of antibiotics in the presence of mid-trimester cervical insufficiency, sterile intra-amniotic inflammation, and amniotic fluid sludge was associated with resolution of the cervical findings, as demonstrated on both sonographic and speculum examination. The patient successfully underwent elective cesarean delivery at 36-2/7 weeks of gestation. This case illustrates that antibiotic therapy may be effective despite the presence of several high-risk pregnancy conditions, and that successful outcome is possible.

Developing a risk profile for spontaneous preterm birth and short interval to delivery among patients with threatened preterm labor

BACKGROUND

Threatened preterm birth is the most common reason for antepartum hospitalization in the United States, accounting for approximately 50% of these admissions. However, fewer than 10% of patients with inpatient evaluation for signs or symptoms of preterm labor ultimately deliver before term.

OBJECTIVE

This study aimed to generate predictive models to assess the risk of preterm delivery and time to delivery based on clinical signs and symptoms of patients evaluated in our institution for preterm labor concerns.

STUDY DESIGN

This was a retrospective cohort study of singleton pregnancies evaluated for signs and/or symptoms of preterm labor, including contractions, abdominal pain, vaginal bleeding, and short cervix, between 22 0/7 and 33 6/7 weeks of gestation. Inpatient evaluations were classified by patient presentation: (1) symptomatic with cervical findings (transvaginal cervical length of <2.5 cm or cervical dilation of ≥2.0 cm), (2) asymptomatic with cervical findings, and (3) symptomatic without cervical findings. The primary outcomes included incidence of spontaneous preterm birth and interval from presentation to delivery, compared between groups. The risk of preterm delivery was evaluated using log-binomial regression, and presentation to delivery timing was assessed by survival analysis and Cox proportional hazards modeling.

RESULTS

Of 631 patients with preterm labor concerns, 96 (16%) were symptomatic with cervical findings on evaluation, 51 (8%) were asymptomatic with cervical findings, and 466 (76%) were symptomatic without cervical findings. The occurrence of preterm birth was significantly higher among symptomatic patients with cervical findings (49%) than among those with cervical findings alone (31%) or symptoms alone (11%) (P<.0001). In addition, symptomatic patients with cervical findings were significantly more likely to deliver within 48 hours (20%), 1 week (30%), 2 weeks (33%), and 1 month (43%) of presentation than patients with cervical findings alone (2%, 2%, 6%, and 10%, respectively) or symptoms alone (0.4%, 1%, 1.5%, and 5%, respectively) (P value for trend<.0001). Adjusted for gestational age at presentation and previous preterm birth, the overall risk of preterm delivery was significantly higher among patients with symptoms and cervical findings than among patients with cervical findings alone (relative risk, 2.81; 95% confidence interval, 1.74-4.54) or symptoms alone (relative risk, 4.39; 95% confidence interval, 3.16-6.09). Adjusted for the same variables, symptomatic patients with cervical findings were also at higher risk of delivery over time after assessment than patients with cervical findings alone (hazard ratio, 2.06; 95% confidence interval, 1.47-2.90) or symptoms alone (hazard ratio, 2.16; 95% confidence interval, 1.74-2.70). The negative predictive value of these models suggested that only 1% of patients with isolated symptoms or cervical findings are at risk of preterm delivery within 1 week of initial presentation.

CONCLUSION

Symptomatic patients with cervical findings suggestive of preterm labor were at the greatest risk of preterm birth and a shorter interval from presentation to delivery. The study findings supported a risk profile that may facilitate the selection of patients most appropriate for admission and targeted management. Nonetheless, as nearly 50% of patients meeting this risk profile subsequently deliver at term, future research is needed to identify which of these patients will require intervention.

The role of vaginal progesterone for preterm birth prevention in women with threatened labor and shortened cervix diagnosed after 24 weeks of pregnancy

OBJECTIVE

To determine whether vaginal progesterone treatment for women with a short cervix, diagnosed after 24 weeks of pregnancy, reduces preterm birth rates.

METHODS

A retrospective cohort study that included women with a singleton pregnancy, threatened preterm labor, and a short cervix measured between 24⁺⁰ and 33⁺⁶ weeks. Women who received vaginal progesterone were compared with women who did not receive progesterone. The primary outcome was spontaneous preterm birth before 37 weeks of pregnancy.

RESULTS

Patients who received vaginal progesterone had a lower rate of preterm delivery at less than 37 weeks of pregnancy (18.2% [22/121] versus 28.9% [73/253]; adjusted hazard ratio 0.50; 95% confidence interval 0.28-0.73, P = 0.001). The diagnosis-to-delivery interval was significantly greater in patients who received progesterone than in those who did not-median time to delivery in weeks: 8.2 (interquartile range [IQR] 6.2-9.8) versus 6.6 (4.8-8.8), (P < 0.001). The frequency of neonatal intensive care unit admission was significantly lower in patients who received progesterone than in those who did not (8.3% [10/121] versus 16.2% [41/253], P = 0.04).

CONCLUSIONS

The administration of vaginal progesterone to patients with an episode of threatened premature labor and a short cervix presenting after 24 weeks of pregnancy was associated with lower rates of premature births.

Second trimester short cervix is associated with decreased abundance of cervicovaginal lipid metabolites

BACKGROUND

A short cervix is a risk factor for preterm birth. The molecular drivers of a short cervix remain elusive. Metabolites may function as mediators of pathologic processes.

OBJECTIVE

We sought to determine if a distinct cervicovaginal metabolomic profile is associated with a short cervix (<25 mm) to unveil the potential mechanisms by which premature cervical remodeling leads to a short cervix.

STUDY DESIGN

This was a secondary analysis of a completed prospective pregnancy cohort. Cervicovaginal fluid was obtained between 20 and 24 weeks' gestation. The participants selected for metabolomic profiling were frequency-matched by birth outcome and cervicovaginal microbiota profile. This analysis included 222 participants with cervical length measured. A short cervix was defined as one having length <25 mm, as measured by transvaginal ultrasound. Unpaired t-tests were performed with a Bonferroni correction for multiple comparisons.

RESULTS

There were 27 participants with a short cervix, and 195 with normal cervical length. Of the 637 metabolites detected, 26 differed between those with a short cervix and those with normal cervical lengths; 22 were decreased, of which 21 belonged to the lipid metabolism pathway (all P<.000079). Diethanolamine, erythritol, progesterone, and mannitol or sorbitol were increased in the cases of short cervix. Among participants with Lactobacillus-deficient microbiota, only diethanolamine and mannitol or sorbitol differed between short cervix (n=17) and normal cervical length (n=75), both increased.

CONCLUSION

A short cervix is associated with decreased cervicovaginal lipid metabolites, particularly sphingolipids. This class of lipids stabilizes cell membranes and protects against environmental exposures. Increased diethanolamine-an immunostimulatory xenobiotic-is associated with a short cervix. These observations begin to identify the potential mechanisms by which modifiable environmental factors may invoke cell damage in the setting of biological vulnerability, thus promoting premature cervical remodeling in spontaneous preterm birth.

The role of digital examination in the setting of a sonographically short cervix

BACKGROUND

Universal transvaginal cervical length screening has been associated with a reduction in the frequency of preterm birth. However, there is no clinically set standard to guide the performance of a digital cervical examination in the setting of a sonographically short cervix.

OBJECTIVE

To investigate the prevalence of cervical dilation at various midtrimester transvaginal cervical length thresholds. Furthermore, we sought to identify sonographic or clinical characteristics associated with cervical dilation that may inform who would benefit from a digital cervical examination in the setting of a sonographically short cervix.

STUDY DESIGN

This retrospective cohort study was conducted at an academic institution and included women with a singleton gestation and an ultrasonographically detected short cervix (defined as a transvaginally obtained cervical length ≤25 mm) who had a documented digital cervical examination within 1 week of the ultrasonography. Bivariable analyses were used to determine the relationship between cervical length and the presence of cervical dilation. Multivariable logistic regression and receiver operating characteristic curve were used to evaluate the relationship between clinical and sonographic risk factors and cervical dilation.

RESULTS

Of the 256 women who met eligibility criteria and had a sonographically detected short cervix, 103 (40.2%) were found to be dilated on digital cervical examination. The prevalence of cervical dilation increased as sonographic cervical length decreased; cervical dilation was identified in 15%, 39%, 53%, 64%, and 69% of women with a cervical length between 20.0 and 25.0 mm, 15.0 and 19.9 mm, 10.0 and 14.9 mm, 5.0 and 9.9 mm, and 0.0 and 4.9 mm, respectively. Maternal race or ethnicity (examined as a social construct), insurance status, nulliparity, previous cervical excisional procedure, funneling on ultrasonography, and sonographic cervical length were each associated with cervical dilation. However, including all of these variables into a regression yielded a model with only moderate predictive ability to identify cervical dilation, with receiver operating area under the curve of 0.77 (95% confidence interval, 0.71-0.83).

CONCLUSION

Consideration should be given to performing a digital cervical examination in the setting of a sonographically short cervix (especially <20 mm) to detect cervical dilation.

Expected-value bias in mid-trimester preterm birth screening

OBJECTIVES

Cervical length (CL) measurement ≤ 25 mm on mid-trimester ultrasound scan is a known risk factor for preterm birth, for which vaginal progesterone is recommended. The aims of this study were to evaluate whether CL measurement is affected by observer bias and to assess the impact on short cervix prevalence of masking CL measurement during routine mid-trimester ultrasound scan.

METHODS

This was a flash study designed for a 2-month period (October and November 2018) at Cruces University Hospital (Bizkaia, Spain), in which all CL measurements from routine mid-trimester scans were masked. During the study period, there was no modification of the routine screening method, and women with a short cervix were prescribed 200 mg vaginal progesterone daily as per usual. The control group included women examined in a 2-month period (April and May 2018) prior to the study, in which CL measurements were taken as usual by a non-blinded operator. The primary outcome was the prevalence of short cervix in each group.

RESULTS

A total of 983 CL measurements were analyzed, including 457 in the blinded group and 526 in the control group. The prevalence of short cervix was 2.7% in the non-blinded group and 5.5% in the blinded group (P = 0.024). We identified a statistically significant difference in the incidence of CL of 24-25 mm between the two groups, with a lower prevalence in the non-blinded vs blinded group (0.6% vs 2.4%; P < 0.005). Moreover, the distribution of CL values was normal in the blinded group, in contrast to the non-blinded group, which was characterized by skewed distribution of CL values.

CONCLUSIONS

Expected-value bias exists and should be taken into account when measuring CL in mid-trimester preterm birth screening. Blinding has demonstrated to be an effective strategy to improve the performance of CL screening in clinical practice. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

A retrospective study analyzing indications and outcomes of mid-trimester emergency cervical cerclage in a tertiary care perinatal centre over half a decade

We studied the indications, success rate, perinatal outcomes and maternal complications following mid-trimester emergency cervical cerclage. All women undergoing mid-trimester emergency cerclage at our centre during 2014-2019 were included in this retrospective study.There were 46 women in our cohort. Mean cervical length was 1.5 cm (SD ± 0.7), and 52.1% of them had bulging membranes. The mean gestational age at cerclage was 23.35 weeks (SD ± 3.341). Three were loss to follow up.Out of 43 pregnancies (23 singletons and 20 twins) analyzed, 37/43, 86.4% had livebirths. Success rate in the singletons and twins were 91.3% and 80% respectively. Maternal complications were seen in 56.5% of patients. Composite neonatal morbidity was significantly more in the twin group (p-value 0.04).Overall live birth rate was 86.4% with similar success rates in singleton and multiple pregnancies. Although, evidence for beneficial effect of prophylactic cerclage in multiple gestation is lacking, emergency cerclage may have a role in twin gestation.

Arabin pessary to prevent adverse perinatal outcomes in twin pregnancies with a short cervix: a multicenter randomized controlled trial (PESSARONE)

BACKGROUND

The number of twin pregnancies continues to increase worldwide as both the number of pregnancies obtained by medically assisted reproduction and age at first pregnancy keep rising. Preterm delivery is the major complication associated with twin pregnancies. The effectiveness of preventive treatments such as progesterone or cervical cerclage for women with a short cervix is doubtful in twin pregnancies. The effectivity of cervical pessaries in preventing preterm birth and its associated morbidity and mortality is also controversial.

OBJECTIVE

We sought to investigate if the Arabin pessary reduces adverse neonatal outcomes in twin pregnancies with a short cervix.

STUDY DESIGN

This open-label, multicenter, randomized controlled trial on twin pregnancies with a cervical length of <35 mm compared pessary placement at 16+0 to 24+0 weeks' gestation with standard care alone. The primary endpoint was a composite of adverse neonatal outcomes, namely peripartum or neonatal death or significant neonatal morbidity before hospital discharge, defined as at least 1 of the following complications: bronchopulmonary dysplasia, intraventricular hemorrhage grade III to IV, periventricular leukomalacia, necrotizing enterocolitis grade II or higher, culture-proven sepsis, and retinopathy requiring treatment. A sample size of 308 pregnancies was planned to ensure 80% power to compare the proportions of women with at least 1 infant with an adverse neonatal outcome. The intention-to-treat analysis after multiple imputation of missing data, was supplemented with a secondary analysis that controlled for gestational age and cervical length, both at inclusion. The primary endpoint was also compared between randomization groups in the per-protocol population, which excluded patients with prespecified major protocol violations (mostly cervical cerclage and/or progesterone after inclusion). Secondary endpoints included preterm birth, spontaneous preterm birth, and pessary side effects.

RESULTS

In total, 315 women were randomized to either receive a pessary (n=157) or standard management (n=158). Overall, 10.8% (34 women) of participants had a missing value for the primary endpoint, mostly (79%) because of the lack of paternal consent for neonatal data collection. In the intention-to-treat analysis, the adverse neonatal outcome occurred in 16.8% of the pessary group vs in 22.5% of the control group (risk ratio, 0.69; 95% confidence interval, 0.39-1.23; P=.210). The per-protocol analysis did not show any significant difference between groups (risk ratio, 0.78; 95% confidence interval, 0.47-1.28; P=.320). The occurrence of preterm birth or spontaneous preterm birth did not differ significantly between groups. No serious side effects were associated with pessary use.

CONCLUSION

Pessary use in our study did not significantly reduce adverse neonatal outcomes in twin pregnancies with a short cervix.

Interventions to prevent preterm delivery in women with short cervix before fetoscopic laser surgery for twin-twin transfusion syndrome

OBJECTIVE

Preoperative short cervical length (CL) remains a major risk factor for preterm birth after laser surgery for twin-twin transfusion syndrome (TTTS), but the optimal intervention to prolong pregnancy remains elusive. The objective of this study was to compare secondary methods for the prevention of preterm birth in twin pregnancies with TTTS undergoing fetoscopic laser photocoagulation (FLP), in the setting of a short cervix at the time of FLP, in five North American Fetal Treatment Network (NAFTNet) centers.

METHODS

This was a secondary analysis of data collected prospectively at five NAFTNet centers, conducted from January 2013 to March 2020. Inclusion criteria were a monochorionic diamniotic twin pregnancy complicated by TTTS, undergoing FLP, with preoperative CL < 30 mm. Management options for a short cervix included expectant management, vaginal progesterone, pessary (Arabin, incontinence or Bioteque cup), cervical cerclage or a combination of two or more treatments. Patients were not included if the intervention was initiated solely on the basis of having a twin gestation rather than at the diagnosis of a short cervix. Demographics, ultrasound characteristics, operative data and outcomes were compared. The primary outcome was FLP-to-delivery interval. Propensity-score matching was performed, with each treatment group matched (1:1) to the expectant-management group for CL, in order to estimate the effect of each treatment on the FLP-to-delivery interval.

RESULTS

A total of 255 women with a twin pregnancy complicated by TTTS and a short cervix undergoing FLP were included in the study. Of these, 151 (59%) were managed expectantly, 32 (13%) had vaginal progesterone only, 21 (8%) had pessary only, 21 (8%) had cervical cerclage only and 30 (12%) had a combination of treatments. A greater proportion of patients in the combined-treatment group had had a prior preterm birth compared with those in the expectant-management group (33% vs 9%; P = 0.01). Mean preoperative CL was shorter in the pessary, cervical-cerclage and combined-treatment groups (14-16 mm) than in the expectant-management and vaginal-progesterone groups (22 mm for both) (P < 0.001). There was no significant difference in FLP-to-delivery interval between the groups, nor in gestational age at delivery or the rate of live birth or neonatal survival. Vaginal progesterone was associated with a decrease in the risk of delivery before 28 weeks' gestation compared with cervical cerclage and combined treatment (P = 0.03). Using propensity-score matching for CL, cervical cerclage was associated with a reduction in FLP-to-delivery interval of 13 days, as compared with expectant management.

CONCLUSIONS

A large proportion of pregnancies with TTTS and a short maternal cervix undergoing FLP were managed expectantly for a short cervix, establishing a high (62%) risk of delivery before 32 weeks in this condition. No treatment that significantly improved outcome was identified; however, there were significant differences in potential confounders and there were also likely to be unmeasured confounders. Cervical cerclage should not be offered as a secondary prevention for preterm birth in twin pregnancies with TTTS and a short cervix undergoing FLP. A large randomized controlled trial is urgently needed to determine the effects of treatments for the prevention of preterm birth in these pregnancies. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

The use of PAMG-1 testing in patients with preterm labor, intact membranes and a short sonographic cervix reduces the rate of unnecessary antenatal glucocorticoid administration

OBJECTIVES

To assess the frequency of antenatal corticosteroid (ACS) administration in cases with shortened cervical length by addition of placental alpha-microglobulin-1 (PAMG-1) testing to sonographic examination.

METHODS

Single centre retrospective cohort study. Rate of ACS administration was compared between cases with cervical length between 15 and 25 mm and cases with positive PAMG-1 testing and cervical length between 15 and 25 mm. We evaluated the following outcome parameters: Rate of ACS administration, gestational age at delivery, time to delivery, delivery within seven days, delivery <34 and <37 weeks' gestation, rate of admission to neonatal intensive care unit (NICU).

RESULTS

In total, 130 cases were included. "PAMG-1 group" consisted of 68 women, 62 cases built the "historical control group". ACS administration was performed less frequently in the "PAMG-1 cohort" (18 (26%) vs. 46 (74%); p<0.001). The rate of delivery within seven days did not differ (2 (3%) vs. 4 (6.5%); p=0.4239). The rates of delivery <34 weeks' gestation (7 (10%) vs. 9 (15%); p=0.4643) and <37 weeks' gestation (19 (28%) vs. 26 (42%); p=0.0939) did not differ. Time to delivery interval was longer in the PAMG-1 group (61.5 vs. 43 days, p=0.0117). NICU admission occurred more often in the "historical control group" (22 (38%) vs. 28 (60%); p=0.0272).

CONCLUSIONS

Addition of biomarker testing can help to avoid unnecessary ACS administrations in women with shortened cervical length.

Utility of follow-up cervical length screening in low-risk women with a cervical length of 26 to 29 mm

BACKGROUND

In women with a previous preterm birth, a protocol for serial cervical length screening has been studied and recommended for the identification and treatment of a short cervix. Cervical length screening along with vaginal progesterone has been suggested for low-risk women with singleton pregnancies to treat a short cervix and reduce preterm birth. However, specific protocols for single vs serial ultrasound measuring cervical length in this population are not established. Cost-effectiveness of universal cervical length screening depends on the cost of screening; follow-up of borderline measurements can contribute to increased costs with uncertain benefit.

OBJECTIVE

This study aimed to determine the utility of follow-up cervical length screening in otherwise low-risk women with singleton pregnancies with a midtrimester cervical length measurement of 26 to 29 mm through the assessment of the rate of short cervix (≤25 mm) on follow-up ultrasound and subsequent delivery outcomes.

STUDY DESIGN

This was a 2-year retrospective cohort study at a single urban institution of women with singleton pregnancies with no previous spontaneous preterm birth and an initial transvaginal ultrasound cervical length measurement of 26 to 29 mm identified during universal cervical length screening at time of anatomy ultrasound (18 0/7 to 22 6/7 weeks' gestation). The primary outcome was the rate of short cervix (defined as ≤25 mm on transvaginal ultrasound) on follow-up ultrasound at <24 weeks' gestation. Secondary outcomes included the rate of spontaneous preterm birth (<37 and <34 weeks' gestation).

RESULTS

During the study period, there were 2801 women with singleton pregnancies at 18 0/7 to 22 6/7 weeks' gestation with transvaginal ultrasound cervical length screening at time of anatomy scan. Among those women, 201 had a cervical length of 26 of 29 mm, and 184 (7%) had no previous spontaneous preterm birth and were included in the study. Furthermore, 144 women (78%) had a follow-up cervical length completed before 24 weeks' gestation. The mean follow-up interval was 1.5±0.6 weeks. Overall, the percentage of short cervix (≤25 mm) on follow-up was 15% (n=21). Baseline characteristics were similar, but the initial cervical length measurement was shorter in women who subsequently developed a short cervix (26.7±0.8 vs 27.8±1.0; P<.01). Delivery outcomes were available for 126 patients. The rate of spontaneous preterm birth at <37 weeks' gestation in women with an initial cervical length 26 to 29 mm and subsequent short cervix was significantly higher than the rate of spontaneous preterm birth in a historical cohort of low risk women with an initial cervical length >25 mm (16% vs 3%; P=.03). The rate of spontaneous preterm birth at <34 weeks' gestation in women with a subsequent short cervix was 11% (2 of 19).

CONCLUSION

Here, approximately 15% of low-risk women with singleton pregnancies with a midtrimester cervical length measurement of 26 to 29 mm will experience cervical shortening of ≤25 mm before 24 weeks' gestation. Compared to women with singleton pregnancies without a history of preterm birth, the rate of spontaneous preterm birth (16%) in women with an initial cervical length of 26 to 29 mm and a subsequent cervical shortening of ≤25 mm is significantly higher. A total of 111 follow-up ultrasounds measuring cervical length would be required to prevent 1 early preterm birth at <34 weeks' gestation.

Cervical length distribution and other sonographic ancillary findings of singleton nulliparous patients at midgestation

BACKGROUND

Short cervix at midgestation, the presence of intraamniotic debris, and cervical funneling are risk factors for preterm birth; however, cervical length measurements and cutoffs are not well documented among pregnant patients of different gestational ages and self-reported races and ethnicities.

OBJECTIVE

This study aimed to describe the distribution of cervical length and frequency of funneling and debris at midgestation in nulliparous women by gestational age and race/ethnicity.

STUDY DESIGN

This secondary analysis of screening data from a multicenter treatment trial of singleton nulliparous patients with short cervix was conducted at 14 geographically distributed, university-affiliated medical centers in the United States. Singleton nulliparous patients with no known risk factors for preterm birth were screened for trial participation and asked to undergo a transvaginal ultrasound to measure cervical length by a certified sonographer. The distribution of cervical length and the frequency of funneling and debris were assessed for each gestational age week (16-22 weeks) and stratified by self-reported race and ethnicity, which for this study were categorized as White, Black, Hispanic, and other. Patients enrolled in the randomized trial were excluded from this analysis.

RESULTS

A total of 12,407 nulliparous patients were included in this analysis. The racial or ethnic distribution of the study participants was as follows: White, 41.6%; Black, 29.6%; Hispanic, 24.2%; and others, 4.6%. The 10th percentile cervical length for the entire cohort was 31.1 mm and, when stratified by race and ethnicity, 31.9 mm for White, 30.2 mm for Black, 31.4 mm for Hispanic, and 31.2 mm for patients of other race and ethnicity (P<.001). At each gestational age, the cervical length corresponding to the tenth percentile was shorter in Black patients. The 25 mm value commonly used to define a short cervix and thought to represent the 10th percentile ranged from 1.3% to 5.4% across gestational age weeks and 1.0% to 3.8% across race and ethnicity groups. Black patients had the highest rate of funneling (2.6%), whereas Hispanic and Black patients had higher rates of intraamniotic debris than White and other patients (P<.001).

CONCLUSION

Black patients had shorter cervical length and higher rates of debris and funneling than White patients. The racial and ethnic disparities in sonographic midtrimester cervical findings may provide insight into the racial disparity in preterm birth rates in the United States.

Cervical pessary plus vaginal progesterone in a singleton pregnancy with a short cervix: an experience-based analysis of cervical pessary's efficacy

BACKGROUND

Several studies were published about cervical pessary, with controversial results. These studies demonstrated that the patient follow-up after pessary insertion is very different between the study centers and the number of pessary insertions per center was often <30 cases. This study aims to determine cervical pessary performance in singleton pregnancies with a short cervix based on a single center learning curve.

METHODS

Between 2011 and 2018, 128 singleton pregnancies between 18 and 24 gestational weeks with a short cervix (<25 mm) were referred to our clinic. All cases were treated with progesterone, and when available in our supplies (due to low resources) cervical pessary was also offered. Three groups were created for statistical analysis: Group 1 (n = 33), treated with progesterone-only; Groups 2 and 3, treated with cervical pessary plus progesterone. Group 2 included the first cases (n = 30) of pessary, defined by a learning curve and cumulative sum analysis, while Group 3 included the subsequent 65 cases. The primary outcome was preterm birth (PTB) < 34 gestational weeks.

RESULTS

The learning curve was performed with all cases of pessary plus progesterone, and 30 patients were obtained as the number needed for learning, in our study with two operators. The PTB rate < 34 weeks was 27.3, 20, and 4.6% in groups 1, 2, and 3, respectively. There was no significant difference between Group 1 and 2 (OR 1.1; 95% CI 0.066 - 18.45; p = .945). When comparing Groups 1 and 3 there was a significant difference in PTB rates (OR 0.08; CI95% 0.01-0.42; p = .003). Considering Kaplan-Meyer Survival analysis, we can observe that the performance of progesterone alone (Group 1) was similar to Group 2 (progesterone + first 30 cases of pessary) (p = .432), but the performance of Group 3 (progesterone + subsequent 65 cases of pessary) and Group 1 shows a statistically significant difference (p = .011).

CONCLUSION

Learning curve and cumulative sum analysis determined that the application and surveillance of at least 30 patients is required to see significant improvements in the primary outcome of PTB < 34 weeks.

The efficacy of therapeutic cervical cerclage in singleton pregnancies: a retrospective study

OBJECTIVES

We compared the pregnancy prolongation effect attributable to cervical cerclage to that achieved by conservative management, and determined the cervical length for which cervical cerclage is effective.

METHODS

We retrospectively examined medical records of 281 women admitted to our hospital between January 2013 and December 2017 for management of threatened preterm birth at 22-28 weeks of gestation. Obstetricians determined suitability for cervical cerclage, which was performed using the McDonald procedure in all cases. Of the 281 subjects, 71 underwent cervical cerclage (cerclage group); the other 210 received conservative therapy (non-cerclage group). We recorded maternal and neonatal characteristics of all patients. The two groups were compared in terms of length of extension of pregnancy and weeks of gestation at delivery. Multivariate analysis was performed to identify factors associated with extension of time to delivery.

RESULTS

Our analyses revealed that the cerclage group was hospitalized earlier in pregnancy than the non-cerclage group (23.7 ± 1.5 weeks vs. 26.4 ± 1.9 weeks, p < .001) and had shorter cervixes (6.0 ± 9.4 mm vs. 16.9 ± 13.0 mm, p < .001). The two groups did not differ significantly in terms of gestational weeks at delivery. Multivariate analysis regarding extension of pregnancy revealed significant differences in extension of pregnancy related with cervical cerclage (26.65 days, 95% CI 17.0 - 36.3, p < .001) and cervical length <10 mm (-27.4 days, 95% CI -36.0--18.8, p < .001). While the time to delivery was extended by cervical cerclage in women with short cervixes (<25 mm), the two groups did not differ when cervical length was ≥15 mm.

CONCLUSIONS

Cervical cerclage was a significant positive factor and short cervix was a significant negative factor for elongating pregnancy. In primigravida and multigravida women with no history of preterm birth, when the cervix is short (<10 mm), cervical cerclage should be recommended.

Personalized assessment of cervical length improves prediction of spontaneous preterm birth: a standard and a percentile calculator

BACKGROUND

A sonographic short cervix (length <25 mm during midgestation) is the most powerful predictor of preterm birth. Current clinical practice assumes that the same cervical length cutoff value should apply to all women when screening for spontaneous preterm birth, yet this approach may be suboptimal.

OBJECTIVE

This study aimed to (1) create a customized cervical length standard that considers relevant maternal characteristics and gestational age at sonographic examination and (2) assess whether the customization of cervical length evaluation improves the prediction of spontaneous preterm birth.

STUDY DESIGN

This retrospective analysis comprises a cohort of 7826 pregnant women enrolled in a longitudinal protocol between January 2006 and April 2017 at the Detroit Medical Center. Study participants met the following inclusion criteria: singleton pregnancy, ≥1 transvaginal sonographic measurements of the cervix, delivery after 20 weeks of gestation, and available relevant demographics and obstetrical history information. Data from women without a history of preterm birth or cervical surgery who delivered at term without progesterone treatment (N=5188) were used to create a customized standard of cervical length. The prediction of the primary outcome, spontaneous preterm birth at <37 weeks of gestation, was assessed in a subset of pregnancies (N=7336) that excluded cases with induced labor before 37 weeks of gestation. Area under the receiver operating characteristic curve and sensitivity at a fixed false-positive rate were calculated for screening at 20 to 23 6/7, 24 to 27 6/7, 28 to 31 6/7, and 32 to 35 6/7 weeks of gestation in asymptomatic patients. Survival analysis was used to determine which method is better at predicting imminent delivery among symptomatic women.

RESULTS

The median cervical length remained fundamentally unchanged until 20 weeks of gestation and subsequently decreased nonlinearly with advancing gestational age among women who delivered at term. The effects of parity and maternal weight and height on the cervical length were dependent on the gestational age at ultrasound examination (interaction, P<.05 for all). Parous women had a longer cervix than nulliparous women, and the difference increased with advancing gestation after adjusting for maternal weight and height. Similarly, maternal weight was nonlinearly associated with a longer cervix, and the effect was greater later in gestation. The sensitivity at a 10% false-positive rate for prediction of spontaneous preterm birth at <37 weeks of gestation by a short cervix ranged from 29% to 40% throughout pregnancy, yet it increased to 50%, 50%, 53%, and 54% at 20 to 23 6/7, 24 to 27 6/7, 28 to 31 6/7, and 32 to 35 6/7 weeks of gestation, respectively, for a low, customized percentile (McNemar test, P<.001 for all). When a cervical length <25 mm was compared to the customized screening at 20 to 23 6/7 weeks of gestation by using a customized percentile cutoff value that ensured the same negative likelihood ratio for both screening methods, the customized approach had a significantly higher (about double) positive likelihood ratio in predicting spontaneous preterm birth at <33, <34, <35, <36, and <37 weeks of gestation. Among symptomatic women, the difference in survival between women with a customized cervical length percentile of ≥10th and those with a customized cervical length percentile of <10th was greater than the difference in survival between women with a cervical length ≥25 mm and those with a cervical length <25 mm.

CONCLUSION

Compared to the use of a cervical length <25 mm, a customized cervical length assessment (1) identifies more women at risk of spontaneous preterm birth and (2) improves the distinction between patients at risk for impending preterm birth in those who have an episode of preterm labor.

The Feasibility of Cervical Elastography in Predicting Preterm Delivery in Singleton Pregnancy with Short Cervix Following Progesterone Treatment

Previous studies demonstrated an association between cervical strain and risk of spontaneous preterm delivery (sPTD). The present study aimed to assess the efficacy of elastography in predicting sPTD at <32 weeks of gestation in women with singleton pregnancies receiving progesterone for short cervix (≤2.5 cm) diagnosed between 16 and 28 weeks of gestation Among 115 participants eligible for analysis, nine had sPTD at <32 weeks. Preprogesterone (PP0) mean internal os strain (IOS), elasticity contrast index (ECI), hardness ratio (HR), one-week postprogesterone (PP1) IOS, mean external os strain (EOS), ECI, and HR were significantly different between groups. Higher PP0 IOS, PP1 IOS, and PP1 EOS were associated with a 2.92, 4.39 and 3.65-fold increase in the risk of sPTD at <32 weeks, respectively (adjusted for cervical length (CL) at diagnosis; p = 0.04, 0.012 and 0.026, respectively). A combination of CL at diagnosis, PP0 IOS and PP1 EOS showed a significantly higher area under the receiver operating characteristic curve (0.858) than that of CL alone (p = 0.041). In women with singleton pregnancies receiving progesterone for short cervix, cervical elastography performed before and one week after progesterone treatment may be useful in predicting sPTD at <32 weeks of gestation.

Cervical Assessment for Predicting Preterm Birth-Cervical Length and Beyond

Preterm birth is considered one of the main etiologies of neonatal death, as well as short- and long-term disability worldwide. A number of pathophysiological processes take place in the final unifying factor of cervical modifications that leads to preterm birth. In women at high risk for preterm birth, cervical assessment is commonly used for prediction and further risk stratification. This review outlines the rationale for cervical length screening for preterm birth prediction in different clinical settings within existing and evolving new technologies to assess cervical remodeling.

Predictors of cerclage failure in singleton pregnancies with a history of preterm birth and a sonographic short cervix

OBJECTIVE

To identify predictors of ultrasound-indicated cerclage failure in singleton pregnancies for preventing extremely preterm birth.

METHODS

A retrospective cohort study included 96 singleton pregnancies with ultrasound-indicated McDonald cerclage in women with previous preterm birth (PTB) and cervical shortening. Descriptive statistics were calculated at baseline and logistic regression analyses were performed to identify the factors associated with cerclage failure.

RESULTS

In all, 28 (29%) of the women had a preterm delivery at before 28 weeks. Multivariate analysis identified cervical dilatation, non-cephalic presentation, and platelet-lymphocyte ratio (PLR) as independent predictors of cerclage failure (odds ratio [OR] 3.12, 95% CI [confidence interval] 1.01-9.66; OR 5.81, 95% CI 1.04-32.53; OR 1.02, 95% CI 1.01-1.03, respectively). The efficacy of these predictors was evaluated using a receiver operating characteristics curve. The area under the curve was 0.87 (95% CI 0.78-0.96, P < 0.001) with a sensitivity of 78.6% and specificity of 88.2%.

CONCLUSION

Our findings indicated that cervical dilatation, fetal presentation, and PLR were valuable predictors of cerclage failure in singleton pregnancies with a history of PTB and a sonographic short cervix. The results can be potentially used to assess the prognosis of patients after cerclage and alert clinicians to consider enhanced surveillance and administration of individuals at an increased risk.

Pessary use in patients diagnosed with short cervix and cervical insufficiency

OBJECTIVE

The aim was to evaluate the effectiveness of Arabin pessary use in patients with cervical insufficiency or short cervix before the 24th week of gestation and the impact of cervical examination findings prior to pessary application on the outcome in terms of the gestational week.

MATERIALS AND METHODS

In our study, among the pregnancies between the 12th and 24th gestational weeks, 60 pregnant women with a preterm delivery history and/or cervical length less than 25 mm were included. Among these 60 patients, 43 of them had a short cervix, 17 of them had cervical insufficiency. Routine medical and obstetric history was obtained. In the vaginal examination, the cervix was evaluated in terms of patency, dilatation, and position. Cervical length, presence of debris, and funneling were evaluated by transvaginal ultrasound. After receiving patients' approval a cervical pessary was applied to patients. Pessaries of pregnant women with 37 weeks of gestation were removed. Before reaching the 37th gestation week, pessaries were withdrawn in patients who had ongoing vaginal bleeding, premature rupture of membranes, and preterm contractions unresponsive to tocolytic treatment.

RESULTS

Thirty-one pregnant women (51.7%) out of 60 pregnant women who underwent pessary, delivered at 37 weeks and below. Delivery rates in the short cervical measurement group and cervical insufficiency group at ≤28 weeks, ≤34 weeks and ≤37 weeks were respectively (n = 21) 34.8% vs 36.3% (p = 0.976), (n = 29) 41.8% vs 64.7% (p = 0.111), (n = 31) 44.2% vs 70.6% (p = 0.888). The presence of cervical funneling before pessary application shows a statistically significant difference in terms of patient's giving birth before or after 28 weeks (p = 0.033). In patients with cervical funneling, there was a significant increase in a birth before 28 weeks. Depending on whether or not patients applying with pain need for tocolysis, it shows the statistically meaningful difference in terms of the patients giving birth before or after 34 weeks (p = 0.001) (OR 7, 61, 95% GA 2.4-24.6). In the group without the need for tocolysis, there is a meaningful increase in birth after 34 weeks.

CONCLUSIONS

Our findings showed that, alongside the defined cervical risk factors, cervical funneling and the need for tocolysis are remarkable prognostic variables in pessary application.

Nomogram to predict the risk of preterm birth before 37 weeks and 34 weeks in pregnant women with a short cervix

OBJECTIVES

This study investigated the potential factors that predict the risk of preterm birth (PTB) in pregnancies with a short cervix. These factors were used to create nomogram, which might be highly sensitive tools to predict the incidence of PTB.

METHODS

This retrospective cohort study enrolled pregnancies with a short cervix from 1 January 2017 to 1 January 2018. The primary outcomes were preterm birth <37 and 34 weeks. Logistic regression model was used to identify potential predictors of PTB. The identified risk factors were used to establish nomograms, which were validated using the receiver operating characteristic (ROC) curve and calibration curve.

RESULTS

In the multivariate analysis, overweight or obesity, parity ≧3 times, twin pregnancy, in vitro fertilization and embryo transfer (IVF-ET), gestational age at first observation of short cervix, cervical length (CL) at first observation of short cervix, history of PTB, and autoimmune disease were found to be predictors of PTB <37 weeks, while twin pregnancy, gestational age at first observation of short cervix, CL of short cervix, history of PTB, and prepregnancy hypertension were predictors of PTB <34 weeks. The area under the ROC curve of the nomogram predicting PTB <37 weeks and PTB <34 weeks were 0.803 and 0.771, respectively. Both models showed good discrimination.

CONCLUSIONS

Gestational age at first observation of short cervix, CL of short cervix and other factors are strong predictors of PTB in pregnancies with a short cervix. Both nomograms showed good discrimination and calibration, and hence might be effective in predicting PTB for this population.

The utility of fetal fibronectin in asymptomatic singleton and twin pregnancies with a cervical length ≤ 10 mm

Objective: To examine the utility of fetal fibronectin (fFN) for predicting spontaneous preterm birth (PTB) in asymptomatic women with a cervical length (CL) ≤10 mm compared to those with a CL 11-25 mm.Methods: Data was collected on all women with nonanomalous singleton and twin gestations who underwent transvaginal CL at a single institution between 2009 and 2012. Women with an incidental short cervix (CL ≤ 25 mm) between 22 and 32 weeks who had an fFN result within 7 days thereafter were included. Indicated preterm deliveries at <14 days of fFN, women who underwent cerclage placement, and terminations of pregnancy were excluded. The primary outcome was spontaneous PTB within 7 and 14 days of the fFN. Sensitivity, specificity, and positive (PPV) and negative predictive value (NPV) of fFN for a CL ≤ 10 mm was calculated for singletons and twins and compared to those with a CL 11-25 mm.Results: Of the 213 women included, 117 (54.9%) were singletons and 96 (45%) were twins. Baseline characteristics were similar between those with a CL ≤ 10 mm and with a CL 11-25 mm in both singletons and twins. The NPV of fFN for delivery within 7 days in singletons and twins with a CL ≤ 10 mm was 100%, similar to those with a CL 11-25 mm (93-100%). The NPV of fFN for delivery within 14 days in singletons and twins with a CL ≤ 10 mm remained high (87.5-100%) when compared to those with a CL 11-25 mm (93-100%). The PPV of fFN for delivery within 7 and 14 days in both singletons and twins with a CL ≤ 10 mm was low (10-25%) and similar to those with a CL 11-25 mm (7.1-24.4%).Conclusions: The NPV of fFN in asymptomatic singleton and twin pregnancies with a CL ≤ 10 mm is high and comparable to the NPV of fFN in women with a longer CL. Routine fFN collection in this select population should be considered as it may avoid unnecessary and costly admissions, as well as assist with timing of antenatal corticosteroids.

Cervical pessary to prevent preterm birth in asymptomatic high-risk women: a systematic review and meta-analysis

BACKGROUND

Randomized controlled trials that have assessed the efficacy of cervical pessary to prevent preterm birth in asymptomatic high-risk women have reported conflicting results.

OBJECTIVE

To evaluate the efficacy and safety of cervical pessary to prevent preterm birth and adverse perinatal outcomes in asymptomatic high-risk women.

DATA SOURCES

MEDLINE, EMBASE, POPLINE, CINAHL, and LILACS (from their inception to October 31, 2019), Cochrane databases, Google Scholar, bibliographies, and conference proceedings.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials that compared cervical pessary with standard care (no pessary) or alternative interventions in asymptomatic women at high risk for preterm birth.

STUDY APPRAISAL AND SYNTHESIS METHODS

The systematic review was conducted according to the Cochrane Handbook guidelines. The primary outcome was spontaneous preterm birth <34 weeks of gestation. Secondary outcomes included adverse pregnancy, maternal, and perinatal outcomes. Pooled relative risks with 95% confidence intervals were calculated. Quality of evidence was assessed using the GRADE methodology.

RESULTS

Twelve studies (4687 women and 7167 fetuses/infants) met the inclusion criteria: 8 evaluated pessary vs no pessary in women with a short cervix, 2 assessed pessary vs no pessary in unselected multiple gestations, and 2 compared pessary vs vaginal progesterone in women with a short cervix. There were no significant differences between the pessary and no pessary groups in the risk of spontaneous preterm birth <34 weeks of gestation among singleton gestations with a cervical length ≤25 mm (relative risk, 0.80; 95% confidence interval, 0.43-1.49; 6 trials, 1982 women; low-quality evidence), unselected twin gestations (relative risk, 1.05; 95% confidence interval, 0.79-1.41; 1 trial, 1177 women; moderate-quality evidence), twin gestations with a cervical length <38 mm (relative risk, 0.75; 95% confidence interval, 0.41-1.36; 3 trials, 1128 women; low-quality evidence), and twin gestations with a cervical length ≤25 mm (relative risk; 0.72, 95% confidence interval, 0.25-2.06; 2 trials, 348 women; low-quality evidence). Overall, no significant differences were observed between the pessary and no pessary groups in preterm birth <37, <32, and <28 weeks of gestation, and most adverse pregnancy, maternal, and perinatal outcomes (low- to moderate-quality evidence for most outcomes). There were no significant differences in the risk of spontaneous preterm birth <34 weeks of gestation between pessary and vaginal progesterone in singleton gestations with a cervical length ≤25 mm (relative risk, 0.99; 95% confidence interval, 0.54-1.83; 1 trial, 246 women; low-quality evidence) and twin gestations with a cervical length <38 mm (relative risk, 0.73; 95% confidence interval, 0.46-1.18; 1 trial, 297 women; very low-quality evidence). Vaginal discharge was significantly more frequent in the pessary group than in the no pessary and vaginal progesterone groups (relative risks, ∼2.20; high-quality evidence).

CONCLUSION

Current evidence does not support the use of cervical pessary to prevent preterm birth or to improve perinatal outcomes in singleton or twin gestations with a short cervix and in unselected twin gestations.

Change in Cervical Length across Pregnancies and Preterm Delivery

OBJECTIVE

This study aimed to determine whether a decrease in midtrimester cervical length across pregnancies is associated with preterm delivery in a subsequent pregnancy.

STUDY DESIGN

This is a cohort study of women who had two consecutive singleton births at the same institution. Midtrimester cervical length change across pregnancies was measured as the difference in centimeters (cm) between cervical lengths using the measurement taken closest to 20^0/7 weeks' gestation in each pregnancy. Cervical length shortening was defined as present if the cervical length decreased by at least one standard deviation in the subsequent pregnancy.

RESULTS

Among 1,552 women, 114 (7.4%) experienced a preterm delivery in the subsequent pregnancy. Compared with women whose subsequent pregnancy cervical length remained stable or increased, women whose cervical length shortened were more likely to experience a preterm delivery (10.3 vs. 6.7%; p = 0.04). Cervical length shortening remained associated with preterm delivery even when accounting for a woman's prior preterm delivery, prior pregnancy short cervix, interdelivery interval, progesterone use, and cervical length in the subsequent pregnancy (adjusted odds ratio = 1.89; 95% confidence interval = 1.11-3.20).

CONCLUSION

Midtrimester cervical length shortening across pregnancies is independently associated with an increased risk of preterm delivery.

Cervicovaginal microbial communities deficient in Lactobacillus species are associated with second trimester short cervix

BACKGROUND

The cervix functions as a barrier to ascending pathogens in pregnancy. Short cervical length and lack of cervicovaginal Lactobacillus species are risk factors for spontaneous preterm birth; however, whether they interact to increase risk remains unknown.

OBJECTIVE

We sought to examine the relationship between cervicovaginal microbiota and short cervix as well as their combined impact on spontaneous preterm birth risk.

STUDY DESIGN

This was a secondary analysis of a prospective nested, case-control pregnancy study. Cervical swabs were collected between 16 and 20 weeks of gestation. Cervical length was measured per standard clinical care during a clinically indicated ultrasound at approximately 20 weeks of gestation. Cervicovaginal microbiota were analyzed with 16S ribosomal RNA gene sequencing and classified into community state types among 67 cases of spontaneous preterm birth, 47 cases of medically indicated preterm birth, and 358 cases of term births. Logistic regression was used to model associations of community state type IV, a community characterized by a paucity of Lactobacillus species and a wide array of anaerobic bacteria, and short cervix (<25 mm) as well as to model the association of a combination of short cervix and community state type IV with the odds of spontaneous preterm birth.

RESULTS

Among the 472 women in the data set, there were 38 with short cervix (8.1%) and 177 with community state type IV (37.5%). Short cervix was associated with spontaneous preterm birth (adjusted odds ratio, 15.59; 95% confidence interval, 6.77-35.92). Women with community state type IV had higher odds of short cervix (adjusted odds ratio, 2.17; 95% confidence interval, 1.04-4.53) as well as spontaneous preterm birth (adjusted odds ratio, 1.97; 95% confidence interval, 1.06-3.65). While the interaction of community state type IV and short cervix was not significant (P = .771), women with both short cervix and community state type IV (n = 20) had higher odds of spontaneous preterm birth compared with women with both normal cervical length and community state types I, II, III, or V (n = 277) (adjusted odds ratio, 21.8; 95% confidence interval, 6.78-70.2).

CONCLUSION

Community state type IV, characterized by a diverse set of strict and facultative anaerobes and a paucity of Lactobacillus species, is associated with increased odds of short cervix. Women with both community state type IV and short cervix have higher odds of spontaneous preterm birth than women with either factor alone. Determining the cascade of events leading to premature cervical shortening, including dysbiosis, may be critical in preventing spontaneous preterm birth.

The use of progesterone during pregnancy to prevent preterm birth

One of the most significant problems facing maternal and children health worldwide is preterm birth (PTB). Although strategies to increase the survival of premature infants have significantly improved in the past few decades, they have yet to be successful. Nine years ago, the use of progesterone in pregnancy was approved by the United States Food and Drug Administration (FDA) for PTB prevention. This paper reviews the recent evidence supporting the use of progesterone in pregnancy for PTB prevention and provides guidelines for its use in daily clinical practice. The guidelines address multiple current controversial areas regarding the prevention of PTB to aid physicians with their clinical decision-making practice, including the use in multifetal gestation, different formulations, safety in pregnancy, dose and route of administration.Saudi Med J 2020; Vol. 41 (4): 333-340doi: 10.15537/smj.2020.4.25036How to cite this article:Alsulmi ES, Alfaraj M, Faden Y, Al Qahtani N. The use of progesterone during pregnancy to prevent preterm birth. Saudi Med J 2020; Vol. 41: 333-340. doi: 10.15537/smj.2020.4.25036.

The risk of spontaneous preterm birth in asymptomatic women with a short cervix (≤25 mm) at 23-28 weeks' gestation

BACKGROUND

Asymptomatic short cervical length is an independent risk factor for spontaneous preterm birth. However, most studies have focused on the associated risk of a short cervical length when encountered between 16 and 23 weeks' gestation. The relationship between cervical length and risk of spontaneous preterm birth after 23 weeks is not well known.

OBJECTIVE

To evaluate the risk of spontaneous preterm birth in asymptomatic women with a short cervix (≤25 mm) at 23-28 weeks' gestation.

MATERIALS AND METHODS

A retrospective cohort study of women with asymptomatic short cervix (cervical length ≤25 mm) at extreme prematurity, defined as 23-28 weeks' gestation, was performed at a single center from January 2015 to March 2018. Women with symptoms of preterm labor, multiple gestations, fetal or uterine anomalies, cervical cerclage, or those with incomplete data were excluded from the study. Demographic information as well as data on risk factors for spontaneous preterm birth were collected. Patients were divided into 4 groups based on the cervical length measurement (≤10 mm, 11-15 mm, 16-20 mm, and 21-25 mm). The primary outcome was time interval from enrollment to delivery. Secondary outcomes included delivery within 1 and 2 weeks of enrollment, gestational age at delivery, and delivery prior to 32, 34, and 37 weeks, respectively. Continuous variables were compared using Kruskal-Wallis test, whereas categorical variables were compared using the χ² or Fisher exact test as appropriate. The Wilcoxon test for difference in survival time was used to compare gestational age at delivery among the 4 cervical length groups, with data stratified based on gestational age at enrollment.

RESULTS

Of the 126 pregnancies that met inclusion criteria, 22 (17.4%) had a cervical length of ≤10 mm, 23 (18.3%) had a cervical length of 11-15 mm, 37 (29.4%) had a cervical length of 16-20 mm, and 44 (34.9%) had a cervical length of 21-25 mm. Baseline characteristics were similar among all 4 groups. The shorter cervical length group was associated with a shorter time interval from enrollment to delivery (cervical length ≤10 mm, 10 weeks; cervical length 11-15 mm, 12.7 weeks; cervical length of 16-20 mm, 13 weeks; cervical length of 21-25 mm, 13.2 weeks; P = .006). Regardless of the cervical length measurement, delivery within 2 weeks was extremely uncommon (1 patient; 0.8%). The prevalence of spontaneous preterm birth at <32 weeks or <34 weeks was higher in women with a cervical length of ≤10 mm compared to those with a longer cervical length (P < .001).

CONCLUSIONS

The risk of spontaneous preterm birth in asymptomatic women with a sonographic short cervix increases as cervical length decreases. The risk is substantially higher in women with a cervical length of ≤10 mm. Women with a cervical length of ≤10 mm also had the shortest time interval to delivery. Nevertheless, delivery within 1 or 2 weeks is highly unlikely, regardless of the cervical length at the time of enrollment. Therefore, based on our data, we suggest that management decisions such as timing of administration of antenatal corticosteroids in asymptomatic patients with a cervical length of ≤25 mm at 23-28 weeks' gestation may be delayed until additional indications are present.

Vaginal progesterone combined with cervical pessary in preventing preterm birth: a meta-analysis

OBJECTIVE

Vaginal progesterone and cervical pessary are both shown to be effective in preventing preterm. We conducted a meta-analysis to evaluate whether the combination of these two interventions has any additional benefit in preventing preterm birth and improving perinatal outcomes in asymptomatic women with a singleton gestation who had a midtrimester sonographic short cervix compared with vaginal progesterone alone.

METHODS

Five databases were searched from their inception to 21 February 2019. We estimated relative risk (RR) and 95% confidence intervals (CIs) for dichotomous outcomes. The primary outcome was preterm birth <34 weeks, and second outcomes included low birth weight (LBW) delivery, perinatal death, and neonatal intensive care unit (NICU) admission.

RESULTS

Three RCTs with a total of 820 participants were identified. Cervical pessary had no significant prevention effect of preterm birth when combined with vaginal progesterone compared to the control group with vaginal progesterone alone (RR = 0.91; 95% CI, 0.47-1.77). No significant difference has been revealed between groups in LBW delivery (RR = 1.13; 95% CI, 0.86-1.48), perinatal death (RR = 1.27; 95% CI, 0.58-2.78) and NICU admission (RR = 1.24; 95% CI, 0.84-1.85).

CONCLUSIONS

Comparing with vaginal progesterone alone, cervical pessary plus vaginal progesterone did not reduce the rates of preterm birth at <34 weeks of gestation. There was no difference in LBW delivery, perinatal death, and NICU admission. We need more evidence to balance the benefit and side effects on the combination of vaginal progesterone and cervical pessary for preventing preterm birth.

The effect of postoperative vaginal progesterone in ultrasound-indicated cerclage to prevent preterm birth

OBJECTIVES

To compare pregnancy outcomes according to the use of postoperative vaginal progesterone in patients who underwent ultrasound-indicated cerclage.

METHODS

This was a retrospective cohort study of 86 consecutive asymptomatic singleton pregnancies who had undergone cerclage because of incidentally found short cervical length under 20 mm through transvaginal ultrasound between 16°^/7 and 24^6/7 weeks' gestational age. Outcomes were compared according to the use of vaginal progesterone after cerclage. Primary outcome measure was preterm delivery < 34 weeks of gestation.

RESULTS

(1) The frequency of preterm delivery < 34 weeks of gestation was significantly lower in patients with postoperative vaginal progesterone than those without (2.2 versus 18.4%, p = .021); (2) the median gestational age at delivery in the postoperative vaginal progesterone group was significantly longer than the control group (38.3 weeks (interquartile range, 37.5-39.1 weeks) versus 37.3 weeks (interquartile range 33.9-38.6 weeks), p = .020); (3) Multivariable logistic regression analysis demonstrated the use of vaginal progesterone after cerclage was found to be independently associated with decrease in preterm delivery before 34 weeks (Odds ratio 0.10; 95% confidence interval, 0.01-0.93) and 37 weeks (Odds ratio 0.24; 95% confidence interval, 0.07-0.85).

CONCLUSIONS

The use of vaginal progesterone was associated with lower rates of preterm birth before 34 and 37 weeks of gestation in women who underwent ultrasound-indicated cerclage placement.

Change in cervical length and spontaneous preterm birth in nulliparous women with a history of loop electrosurgical excision procedure

BACKGROUND

Prior studies have shown an association between history of loop electrode procedures (LEEP) and spontaneous preterm delivery (SPTD) independent of mid-trimester cervical length. These studies suggest that there may be other factors beyond an individual cervical length, which contribute to identifying at-risk pregnancies.

OBJECTIVE

The objective of this study is to determine the association between change in cervical length and SPTD in women with a history of LEEP.

STUDY DESIGN

This is a retrospective cohort study of singleton nulliparous women with a history of LEEP who received serial cervical length measurements at a single institution between 2012 and 2016. Women with serial cervical lengths and available outcome data were included. The cervical length at different gestational ages and the rate of change in length were compared with the risk for SPTD <37 weeks using Student's t-test.

RESULTS

One-hundred-thirty subjects met the inclusion criteria for the study. The mean cervical length (35.3 versus 39.8 mm, p = .042 at 16 weeks; 32.2 versus 37.8 mm, p < .01 at 20 weeks; 29.9 versus 35.6 mm, p = .027 at 24 weeks; 21.6 versus 33.4 mm, p < .01 at 28 weeks) was significantly different between women who had an SPTD <37 weeks compared to women who did not. The average rate of change in transvaginal cervical length between 16 to 28 weeks was significantly different between women who had an SPTD <37 weeks compared to women who did not (-1.4 versus 0.4 mm/week, p < .01).

CONCLUSION

Women with a history of LEEP who had an SPTD <37 weeks had a shorter cervical length at 16, 20, 24, and 28 weeks' gestation and a higher rate of change in cervical length between 16 and 28 weeks than women without a history of SPTD. Our findings support the concept of the preterm birth syndrome as an evolving biophysical process rather than a distinct event, suggesting improved prediction in the setting of prior history of a LEEP with serial imaging.

Cervical pessary for preventing preterm birth in twin pregnancies with maternal short cervix after an episode of threatened preterm labor: randomised controlled trial

BACKGROUND

No intervention has proved effective to date in reducing the spontaneous preterm birth rate in twin pregnancies following an episode of threatened preterm labor and with a short cervix remaining. This study was designed to ascertain whether cervical pessaries are useful in preventing spontaneous preterm birth in women with twin pregnancies and a short cervix remaining after a threatened preterm labor episode.

STUDY DESIGN

This open, randomized, controlled trial was conducted in 132 pregnant women who had not delivered 48 hours after a threatened preterm labor episode and had a short cervix remaining (≤20 mm between 24⁰ and 29⁶ weeks and ≤10 mm between 30⁰ and 33⁶ weeks). Patients were randomly assigned to cervical pessary (n = 67) or routine management (n = 65). The primary outcome was the spontaneous preterm birth rate before 34 weeks. Spontaneous preterm birth before 28 and 37 weeks and neonatal morbidity and mortality were also evaluated in an intention-to-treat analysis.

RESULTS

Significant differences were observed in the spontaneous preterm birth rate before 34 weeks between the pessary and routine management groups (11 of 67 [16.4%] in the pessary group vs 21 of 65 [32.3%] in the control group; relative risk, 0.51 [confidence interval, 0.27-0.97]; P = .03). No significant differences were observed in the preterm birth rate < 28 weeks or < 37 weeks between groups. The pessary group less frequently required readmission for new threatened preterm labor episodes (4 of 67 [5.6%] vs 14 of 65 [21.5%]; relative risk, 0.28 [confidence interval, 0.10-0.80]; P = .009). Significant reduction was observed in the number of neonates weighing less than 2500 g (17.9% [24 of 134] vs 70.8% [92 of 130]; relative risk, 0.25 [confidence interval, 0.15-0.43]; P < .0001).

CONCLUSION

Pessary use did significantly lower the spontaneous preterm birth rate before 34 weeks in twin pregnancies with maternal short cervix remaining after a threatened preterm labor episode. Pessary use also reduced the threatened preterm labor recurrence and neonates' weight less than 2500 g.

The impact of cerclage in twin pregnancies on preterm birth rate before 32 weeks

PURPOSE

To evaluate whether cerclage in twins reduces the rate of spontaneous preterm birth <32 weeks when compared to expectant management.

METHODS

This is a retrospective cohort study of twin pregnancies with the following indications for cerclage from two institutions: history of prior preterm birth, ultrasound-identified short cervix ≤2.5 cm, and cervical dilation ≥1.0 cm. The "cerclage" cohort received a cerclage from a single provider at a single institution from 2003-2016. The "no cerclage" group included all patients with similar indications that were expectantly managed from 2010-2015, at a second institution where cerclages are routinely not performed in twin pregnancies. The primary outcome was the rate of spontaneous preterm birth at <32 weeks. Secondary outcomes were the rates of spontaneous and overall (including medically indicated) preterm births at <32 weeks, < 34 weeks, and <36 weeks, chorioamnionitis, birth weight, and neonatal mortality within 30 days of life. We also performed a planned subgroup analysis stratified by cerclage indication.

RESULTS

In all, 135 women were included in two cohorts: cerclage (n = 96) or no cerclage (n = 39). The rates of spontaneous preterm birth <32 weeks were 10.4% (n = 10) with cerclage versus 28.2% (n = 11) without cerclage (OR 0.23, CI 0.08-0.70, p = .017). After adjusting for cerclage indication, clinical history, age, chorionicity, insurance type, race, BMI, in-vitro fertilization, and multifetal reduction, there remained a significant reduction in the cerclage group of spontaneous preterm birth <32 weeks (adjusted odds ratio (aOR) 0.24, CI 0.06-0.90, p = .035), spontaneous preterm birth <36 weeks (aOR 0.34, CI 0.04-0.81, p = .013) as well as in overall preterm birth <32 weeks (aOR 0.31, CI 0.1-0.86, p = .018), and overall preterm birth <36 weeks (aOR 0.37, CI 0.10-0.84, p = .030). When stratified by short cervix or cervical dilation in the cerclage versus no cerclage groups, there was a significant decrease in spontaneous preterm birth <32 weeks in the cerclage group with cervical dilation (11.1 versus 41.2%, p = .01) but not in the cerclage group with short cervix only, even for cervical length <1.5 cm. Pregnancy latency was 91 days in the cerclage group versus 57 days in the no cerclage group (p = .001), with a median gestational age at delivery of 35 versus 32 weeks (p = .002). There was no increase in chorioamnionitis in the cerclage group. Furthermore, there was a significant increase in birth weight (median 2278 versus 1665 g, p < .001) and decrease in perinatal death <30 days (1.6 versus 12.9%, p = .001).

CONCLUSIONS

Cerclage in twin pregnancies significantly decreased the rate of spontaneous preterm birth <32 weeks compared to expectant management. However, when stratified by cerclage indication, this decrease in primary outcome only remained significant in the group with cervical dilation.

Prolonged early antenatal indomethacin exposure is safe for fetus and neonate. J Matern Fetal Neonatal Med 2019;34:167-176. [PMID: 30905227 DOI: 10.1080/14767058.2019.1599351]

Objective: To evaluate fetal and neonatal safety of early-onset long-term antenatal indomethacin treatment (LIT) for short cervix.Methods: In this cohort study, women started LIT for short cervix (<25 mm) before completing 25 weeks. They followed a standardized regiment of oral indomethacin: 100 mg loading, 50 mg qid for 48 h, 25 mg qid until delivery or at 32 weeks gestational age (GA), whichever comes first. Weekly monitoring for oligohydramnios and ductus arteriosus (DA) constriction included confirmation of compliance with treatment/dose. This approach is established in our clinical practice. To identify LIT complications separate from prematurity, each neonate exposed to LIT were matched to two unexposed neonatal controls within ±3 days of GA of delivery and birth weight of ±10%. Odds ratios for neonatal variables included pulmonary hemorrhage, patent DA (PDA) requiring medical or surgical correction, necrotizing enterocolitis (NEC), spontaneous intestinal perforation (SIP), intraventricular hemorrhage (IVH) grade III-IV, other intracranial hemorrhage (ICH), neonatal mortality, calculated individually, and for total composite morbidity. Statistical determinants of neonatal morbidity were assessed using binary logistic regression. Exposure to LIT, maternal age, parity, BMI, GA at delivery, birth-weight (BW), neonatal gender, cord artery pH, and 5-min Apgar score were independent variables.Results: 166 LIT cases were matched with 332 controls. LIT median duration was 49 (3-108) days. Mean delivery GA was 34 weeks. LIT was stopped for 5 patients (2.9%) with oligohydramnios and 1 (0.6%) with DA constriction, without consequent morbidity. 71 cases (43%) completed LIT, stopping at 32 weeks. 95 stopped early for preterm premature ruptures of membranes (PPROM) (20%), active labor (11%) or patient choice (22%). Odds of any individual complication did not differ between treated cases and controls. LIT was not a statistical determinant of composite morbidity or any individual neonatal problem.Conclusion: Continuous early-onset indomethacin exposure, up to 15 weeks antenatally, did not increase fetal or neonatal complications. This level of safety is permissive to a randomized trial of indomethacin for the treatment of short cervix.

Should phenotype of previous preterm birth influence management of women with short cervix in subsequent pregnancy? Comparison of vaginal progesterone and Arabin pessary

OBJECTIVE

To investigate whether the classification of a previous spontaneous preterm birth (sPTB) as preterm labor (PTL) with intact membranes (IM) or as preterm prelabor rupture of membranes (PPROM) impacts the efficacy of cervical pessary or vaginal progesterone for prevention of sPTB in pregnant women with short cervix on transvaginal ultrasound.

METHODS

This was a retrospective cohort study of asymptomatic high-risk singleton pregnancies with a short cervix and history of sPTB, treated using Arabin pessary or vaginal progesterone for primary PTB prevention, conducted at four European hospitals. A log-rank test on Kaplan-Meier curves was used to assess the difference in performance of pessary and progesterone, according to history of PTL-IM or PPROM. Linear regression analysis was used to evaluate significant predictors of gestational age at delivery.

RESULTS

Between 2008 and 2015, 170 women were treated with a pessary and 88 with vaginal progesterone. In women treated with a pessary, rate of sPTB < 34 weeks was 16% in those with a history of PTL-IM and 55% in those with a history of PPROM. In women treated with progesterone, rate of sPTB < 34 weeks was 13% in those with a history of PTL-IM and 21% in those with a history of PPROM. Treatment with a pessary resulted in earlier delivery in women with previous PPROM than in any other subgroup (P < 0.0001). Linear regression analysis showed a clear effect of PPROM history (P < 0.0001), combination of PPROM history and treatment (P = 0.0003) and cervical length (P = 0.0004) on gestational age at birth.

CONCLUSIONS

Cervical pessary may be a less efficacious treatment option for women with previous PPROM; however, these results require prospective validation before change in practice is recommended. Phenotype of previous preterm birth may be an important risk predictor and treatment effect modifier; this information should be reported in future clinical trials. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Antibiotic treatment for patients with amniotic fluid "sludge" to prevent spontaneous preterm birth: A historically controlled observational study

INTRODUCTION

Amniotic fluid "sludge" has been associated with an increased rate of spontaneous preterm delivery before 35 weeks, a higher frequency of clinical and histologic chorioamnionitis in a high-risk population. Only one study evaluating the use of antibiotics in the presence of amniotic fluid "sludge" showed reduced rates of spontaneous preterm birth at <34 weeks. The objective of this study was to evaluate routine antibiotic treatment in the presence of amniotic fluid "sludge" for prevention of preterm delivery.

MATERIAL AND METHODS

A historically controlled observational study was performed between October 2010 and January 2015, including a total of 86 pregnant women with singleton pregnancies and the presence of amniotic fluid "sludge" at ultrasound. Women admitted from October 2010 to September 2012 received no treatment with antibiotics, whereas those admitted from October 2012 to January 2015, received routinely clindamycin and first-generation cephalosporin. The groups were compared considering the incidence of spontaneous preterm delivery. The effect of antimicrobials was also compared in the subgroup of women at high risk for spontaneous preterm birth (ie, cervical length ≤25 mm, history of spontaneous preterm birth, previous spontaneous loss in the second trimester, Mullerian malformations or cervical conization).

RESULTS

Antibiotic therapy reduced the incidence of spontaneous preterm birth at <34 weeks (13.2% vs 38.5%, P = 0.047) in women at high-risk for preterm birth, with an odds ratio of 0.24 (95% confidence interval [CI] 0.06-0.99). Birthweight was significantly different between the study groups (2961 ± 705 vs. 2554 ± 819 g, respectively; P = 0.028), with no statistical significance for others variables.

CONCLUSIONS

This study suggests that antibiotic treatment in high-risk pregnant women with amniotic fluid "sludge" can be effective in the reduction of the frequency of spontaneous preterm delivery and can increase the birthweight.