Vaginal progesterone for preventing preterm birth and adverse perinatal outcomes in twin gestations: a systematic review and meta-analysis

Update on Management and Outcomes of Monochorionic Twin Pregnancies

The management of multiple pregnancies complicated by monochorionicity continues to evolve as new investigations support a change in clinical practice to optimize outcomes. Monochorionic twins are at risk of unique conditions such as monoamnionicity, conjoined twinning, twin reversed arterial perfusion sequence, twin-twin transfusion syndrome, twin anemia-polycythemia sequence, unequal placental sharing with discordant twin growth or selective fetal growth restriction, and single-twin death that puts co-twins at risk of death or neurologic injury attributable to the shared placenta. Contemporary practice guidelines recommend serial ultrasonographic surveillance of monochorionic pregnancies to increase the early detection of problems and timely management decisions that may include increased surveillance, selective reduction or pregnancy termination, referral for in utero treatment, or earlier delivery than initially planned. Improvements in prenatal diagnosis and antenatal testing and advances in fetal therapy have contributed to more favorable outcomes in these complicated monochorionic gestations.

Outcomes of emergency cervical cerclage after amnioreduction in twin pregnancies with a fully dilated cervix and amniotic membrane prolapse

Objective

The aim of this study was to evaluate the effectiveness of emergency cervical cerclage (EmC) in twin pregnancies with a fully dilated cervix and amniotic membrane prolapse.

Material and Methods

This retrospective study examined records from December 2015 to December 2022 and included 20 twin pregnancies. The patients were divided into two groups, the EmC group (EmC group) and the no EmC (control) group, and pregnancy outcomes were compared.

Results

EmC was performed after amnioreduction in 11 twin pregnancies. Nine patients who refused EmC were followed up with expectant management. The mean gestational age at first examination was similar between the EmC (21.36±1.62 weeks) and control group (21.00±3.16 weeks, p=0.372). The median (range) volume of removed amniotic fluid was 151.82 (120-420) mL. Cases in the EmC group gained a significantly longer delay until delivery (47.72±28.14 days) compared to controls (2.33±0.5 days, p<0.001). All of the women in the control group gave birth within three days following admission to hospital. The mean gestational age at birth was significantly higher in the EmC group (28.18±4.53 weeks) than in the control group (21.57±3.53 weeks, p<0.001). Thirteen (59.09%) infants survived in the EmC group while only two infants (22.22%) of one patient survived in the control group (p<0.001).

Conclusion

EmC increases the survival rate of infants by prolonging the gestational age at delivery in twin pregnancies. Clinicians and patients should be encouraged regarding the use of EmC in twin pregnancies with a fully dilated cervix and prolapsed amniotic membranes.

Cervical assessment

Transvaginal scan (TVS) of cervical length (CxL) at mid-trimester anomaly scan in asymptomatic pregnancy is useful for predicting the risk of preterm birth. In symptomatic women, measurement of CxL at presentation can help to distinguish between true and false preterm labor (PTL), and who might not deliver within 48 h and seven days. In both groups, the individualization of risk would lead to improvement of antenatal care, including frequency of visits, patient education to identify earlier symptoms, avoid excessive hospitalization, and unnecessary steroids. It is also possible that vaginal progesterone and/or cerclage reduce the PTB risk on those asymptomatic women with short cervix. The aim is to review the evidence that supports the use of TVS of CxL in both asymptomatic and symptomatic pregnant women for the prediction and management of PTL.

The effectiveness of ultrasound-indicated cerclage for the reduction of extreme preterm birth in twin pregnancies with a short cervix: a systematic review and meta-analysis

OBJECTIVE

This study aimed to evaluate the effectiveness of cervical cerclage in women with a twin pregnancy and a midpregnancy asymptomatic short cervix (≤25 mm), in preventing preterm birth and improving neonatal outcomes.

DATA SOURCES

Systematic searches were conducted in MEDLINE, Embase, Web of Science, Scopus, and Cochrane Library up to April 17, 2023, updated in September and February 2024.

STUDY ELIGIBILITY CRITERIA

Included were randomized controlled trials, cohort studies, and case-control studies comparing cerclage with expectant management in twin pregnancies and an asymptomatic short cervix (≤25 mm).

METHODS

Risk of bias was assessed using the Newcastle-Ottawa Quality Assessment Scale and the Risk of Bias 2 tool. Data were analyzed using RevMan 5.4 using a random-effects model.

RESULTS

Three randomized controlled trials and 13 cohort studies, involving 696 cerclage patients and 595 controls, were analyzed. Combined randomized controlled trial findings (N=49) found no significant difference in preterm birth occurrence after adjustment for preterm birth history and gestational age. Neonates from cerclage-treated mothers exhibited significantly higher rates of respiratory distress syndrome (adjusted odds ratio, 3.88; 95% confidence interval, 1.09-21.03) and very low birthweight (adjusted odds ratio, 2.22; 95% confidence interval, 1.07-5.73). In contrast, pooled cohort data indicated significantly less preterm birth rates in women with a cerclage: at 34 weeks (relative risk, 0.75; 95% confidence interval, 0.63-0.90), 32 weeks (relative risk, 0.67; 95% confidence interval, 0.49-0.90), and 28 weeks (relative risk, 0.572; 95% confidence interval, 0.39-0.83). Cerclage also reduced risk for infants <1500 g, respiratory distress syndrome, admission at the neonatal intensive care unit, and sepsis. Women with cervical length <15 mm and a cerclage experienced fewer preterm birth rates at <37 weeks (relative risk, 0.88; 95% confidence interval, 0.81-0.94), 34 weeks (relative risk, 0.70; 95% confidence interval, 0.57-0.87), 32 weeks (relative risk, 0.63; 95% confidence interval, 0.50-0.80), and 28 weeks (relative risk, 0.43; 95% confidence interval, 0.32-0.59). Perinatal mortality risk was significant lower in neonates born to mothers with a cerclage. For women with cervical length between 16 and 25 mm, no significant differences in outcomes were observed.

CONCLUSION

Based on our meta-analysis, cerclage may benefit women with a twin pregnancy with an asymptomatic midpregnancy short cervix <25 mm, especially in women with a cervix <15 mm, by reducing preterm birth and improving neonatal outcomes. However, the differences between randomized controlled trials and recent cohort studies emphasize the need for well-powered randomized controlled trials on neonatal outcomes before introducing cerclage in clinical practice for these women.

Variation between countries for routine transvaginal cervical length measurement and interventions to prevent preterm birth

OBJECTIVE

To assess the variation between countries for routine transvaginal ultrasound assessment of the cervical length and interventions offered to prevent preterm birth (PTB).

STUDY DESIGN

An anonymous digital questionnaire was sent out between August and October 2023 to delegates of the European Spontaneous Preterm Birth Congress. Outcomes assessed included method, indications (i.e. singleton pregnancy in women with or without a history of PTB, or a multiple pregnancy), timing and frequency of routine cervical length measurement, interventions offered to pregnant women with a short cervix or a history of PTB, and advice on physical- and sexual activity.

RESULTS

In total, 247 visitors of the European Spontaneous Preterm Birth Congress were approached for this study and 103 (42 %) participants completed the questionnaire representing 15 countries. Most participants worked in a Public/University hospital (n = 54, 53 %) and worked as a specialist (registrar or consultant; n = 84, 82 %). In most countries, the cervix was measured via a straight-line method without the cervical isthmus, but variety existed also within countries. Routine cervical length measurement in women with no prior PTB or a multiple pregnancy is rarely performed in the first trimester. For women with a history of PTB, 39 (38 %) respondents from six countries reported to start serial cervical measurement in the first trimester and 99 (96 %) from 14 countries in the second trimester. Follow-up for women at risk for PTB mainly occurs fortnightly (n = 40, 39 %) or monthly (n = 14, 14 %). However, follow-up is often individualized according to patient's history and/or cervical length. In women with a history of PTB or a short cervix progesterone is administered vaginally (n = 99, 96 %), however dosage vary between 100 mg and 400 mg daily. The timing and gestational age at which a (primary/secondary/tertiary) vaginal cerclage is offered widely differ between countries (e.g. up to 24-28 weeks of gestation for a secondary cerclage). Advice on restrictions regarding sexual activity in pregnancy is frequently prescribed for women with a short cervix (n = 38, 37 %).

CONCLUSION

Substantial variation exist between and within countries regarding the indications and timing of cervical length measurement and interventions offered. There is a need for a more universal approach to manage patients at risk for PTB based on the existing evidence.

Long-term effect of fine particulate matter constituents on reproductive hormones homeostasis in women attending assisted reproductive technologies: A population-based longitudinal study

Fine particulate matter (PM2.5) may disrupt women's reproductive hormones, posing potential reproductive risks. However, the exact compositions of PM2.5 responsible for these effects remain unclear. Our investigation explored the long-term impacts of PM2.5 constituents on reproductive hormones, based on a large longitudinal assisted reproductive cohort study in Anhui, China. We included 24,396 reproductive hormone samples from 19,845 women attending assisted reproductive technologies (ART) between 2014 and 2020. Using high-resolution gridded data (1-km resolution), we calculated the residence-specified PM2.5 constituents during the year before the month of hormone testing. Relationships between PM2.5 constituents [organic matter (OM), chloride (Cl-), sulfate (SO42-), ammonium (NH4+), black carbon, and nitrate] and reproductive hormones were investigated using the linear mixed model with subject-specific intercepts. The constituent-proportion model and the constituent-residual model were also constructed. Additionally, cubic spline analysis was used to examine the potential non-linear exposure-response relationship. We found that per interquartile range (IQR) increment in OM was associated with a 5.31 % (3.74 %, 6.89 %) increase in estradiol, and per IQR increment in Cl- and NH4+ were associated with 13.56 % (7.63 %, 19.82 %) and 9.07 % (4.35 %, 14.01 %) increases in luteinizing hormone. Conversely, per IQR increment in OM and Cl- were associated with -7.27 % (-9.34 %, -5.16 %) and -8.52 % (-10.99 %, -5.98 %) decreases in progesterone, and per IQR increment in SO42- was associated with a -9.15 % (-10.31 %, -7.98 %) decrease in testosterone. These associations were held in both proportional and residual models. Moreover, exposure-response curves for estradiol and progesterone with PM2.5 constituents exhibited approximately U-shaped. These results suggested that specific PM2.5 constituents might disrupt reproductive hormone homeostasis in women attending ART, providing new evidence for formulating PM2.5 pollution reduction strategies that could benefit women's reproductive health.

Prevention of preterm birth in twin-to-twin transfusion syndrome: a systematic review and network meta-analysis

OBJECTIVES

We aimed to perform a systematic review and network meta-analysis to evaluate the preventive strategies for preterm birth in twin-to-twin transfusion syndrome.

METHODS

PubMed, Embase and Cochrane Central were searched from inception to December 2023 with no filters. Additionally, the reference lists of the included studies were manually examined to identify any supplementary studies. We selected randomized controlled trials and cohorts comparing interventions to prevent preterm birth in twin pregnancies complicated by twin-to-twin transfusion syndrome. A random-effects frequentist network meta-analysis was performed using RStudio version 4.3.1. Randomized controlled trials and cohorts were assessed respectively using the Risk of Bias in Non-randomized Studies of interventions tool and Cochrane Collaboration's tool for assessing risk of bias in randomized trials.

RESULTS

In this systematic review and meta-analysis, we included eight studies comprising a total of 719 patients. Compared with expectant management, cerclage stood out as the only intervention associated with an increase in the survival of at least one twin (risk ratio 1.12; 95 % confidence interval 1.01-1.23). Our subgroup analysis based on different thresholds for short cervix demonstrated a significant reduction in the risk of preterm birth before 32 weeks with ultrasound-indicated cerclage using a 15 mm criterion (risk ratio 0.65; 95 % confidence interval 0.47-0.92).

CONCLUSIONS

Our study suggests the potential benefit of cerclage as a preventive strategy for preterm birth in pregnancies complicated by twin-to-twin transfusion syndrome. These findings highlight the necessity for further investigation to corroborate our results and address the optimal threshold for ultrasound-indicated cerclage.

Vaginal Progesterone for Pregnancy Prolongation After Arrested Preterm Labor: A Randomized Clinical Trial

Importance

Women with arrested preterm labor (APTL) are at very high risk for spontaneous preterm delivery (SPTD), the leading cause of neonatal mortality and morbidity. To date, no maintenance therapy has been found to be effective for pregnancy prolongation. A few clinical trials with considerable methodological limitations have demonstrated some efficacy for 400 mg vaginal micronized progesterone (VMP) in women with APTL.

Objective

To investigate the effectiveness of daily 400 mg VMP for the prolongation of pregnancy after APTL.

Design, Setting, and Participants

This randomized clinical trial was conducted between December 19, 2018, and February 27, 2023, in 3 university-affiliated medical centers in Israel. Participants included women with singleton and twin pregnancies after APTL following tocolysis at 24 weeks 0 days to 34 weeks 0 days' gestation. Women with a history of preterm delivery or asymptomatic cervical shortening in the current pregnancy were excluded.

Interventions

Participants were randomly allocated to receive VMP 200 mg twice a day or no treatment until 36 weeks 6 days' gestation.

Main Outcomes and Measures

The primary end points were mean number of days from study enrollment to delivery and the rate of SPTD prior to 37 weeks' gestation.

Results

A total of 129 participants were enrolled (65 in the VMP group and 64 in the no-treatment group). Mean (SD) age was 27.6 (5.1) years. Between the VMP and no-treatment groups, there was no difference in pregnancy prolongation (mean [SD], 40.0 [17.8] vs 37.4 [20.3] days; P = .44) and the rate of SPTD (16 [25%] vs 19 [30%]; relative risk, 0.8; 95% CI, 0.5-1.5; P = .52). In twin pregnancies, including 12 and 15 pairs in the VMP and no-treatment groups, respectively, VMP prolonged pregnancy (mean [SD], 43.7 [18.1] vs 26.1 [15.2] days; P = .02), postponed the delivery week (36.5 [1.4] vs 34.7 [2.2] weeks; P = .01), shortened the length of stay in the neonatal intensive care unit (4.9 [10.6] vs 13.2 [18.5] days; P = .03) and overall hospital stay (8.3 [9.6] vs 15.1 [17.2] days; P = .03), and was associated with a higher birth weight (2444 [528] vs 2018 [430] g; P = .01).

Conclusions and Relevance

These findings show that VMP given in a dosage of 200 mg twice a day following APTL is not an effective treatment to prolong pregnancy or prevent SPTD. However, VMP demonstrated beneficial effects in twin pregnancies, warranting further investigation.

Trial Registration

ClinicalTrials.gov Identifier: NCT02430233.

Longitudinal evaluation of cervical length and shear wave elastography in women with spontaneous preterm birth

OBJECTIVE

To evaluate longitudinal changes in cervical length (CL) and mean cervical shear wave elastography (CSWE) score in women with a singleton or twin pregnancy who undergo spontaneous preterm birth (sPTB) compared with those who deliver at term.

METHODS

This was a prospective longitudinal study of unselected women with a singleton or twin pregnancy attending a dedicated research clinic for screening for sPTB at four timepoints during pregnancy: 11 + 0 to 15 + 6 weeks, 16 + 0 to 20 + 6 weeks, 21 + 0 to 24 + 6 weeks and 28 + 0 to 32 + 6 weeks. At each visit, a transvaginal ultrasound scan was conducted to measure the CL and the CSWE scores in six regions of interest (ROI) (inner, middle and external parts of anterior and posterior cervical lips). The mean CSWE score from the six ROIs was calculated for analysis. Log10 transformation was applied to data to produce a Gaussian distribution prior to statistical analysis. A multilevel mixed-effects analysis was performed to compare longitudinally CL and CSWE between the sPTB and term-delivery groups.

RESULTS

The final cohort consisted of 1264 women, including 1143 singleton pregnancies, of which 57 (5.0%) were complicated by sPTB, and 121 twin pregnancies, of which 33 (27.3%) were complicated by sPTB. Compared to those who delivered at term, women with sPTB had a lower CL across gestation when controlling for history of cervical surgery, number of fetuses, gestational age (GA) at cervical assessment and the interaction between GA at cervical assessment and sPTB (P < 0.001). Specifically, CL in the sPTB group was significantly lower at 21 + 0 to 24 + 6 weeks (P = 0.039) and 28 + 0 to 32 + 6 weeks (P < 0.001). Twin pregnancies had significantly greater CL throughout pregnancy compared with singleton pregnancies (regression coefficient, 0.01864; P < 0.001). After adjusting for maternal age, weight, height, body mass index and GA at cervical assessment, CSWE score in the sPTB group was significantly lower compared with that in the term-delivery group across gestation (P = 0.013). However, on analysis of individual visits, CSWE score in the sPTB group was significantly lower than that in the term-delivery group only at 11 + 0 to 15 + 6 weeks (P = 0.036). There was no difference in CSWE score between singleton and twin pregnancies throughout gestation (regression coefficient, -0.00128; P = 0.937).

CONCLUSIONS

Women with sPTB have a shorter and softer cervix across gestation compared with those who deliver at term. A shorter cervix in the sPTB group is observed from the late second trimester onwards, while lower cervical stiffness in the sPTB group is observed primarily in the first trimester. CL is significantly lower in singleton pregnancies compared with twin pregnancies, while cervical stiffness does not differ between the two. Our findings indicate that the cervix tends to undergo a softening process prior to shortening in sPTB cases. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Etiologically Based Functional Taxonomy of the Preterm Birth Syndrome

Preterm birth (PTB) is a complex syndrome traditionally defined by a single parameter, namely, gestational age at birth (ie, ˂37 weeks). This approach has limitations for clinical usefulness and may explain the lack of progress in identifying cause-specific effective interventions. The authors offer a framework for a functional taxonomy of PTB based on (1) conceptual principles established a priori; (2) known etiologic factors; (3) specific, prospectively identified obstetric and neonatal clinical phenotypes; and (4) postnatal follow-up of growth and development up to 2 years of age. This taxonomy includes maternal, placental, and fetal conditions routinely recorded in data collection systems.

The effect of cervical pessary on increasing gestational age at delivery in twin pregnancies with asymptomatic short cervix: a systematic review and meta-analysis of randomized controlled trials

Objective

The incidence of preterm delivery is much higher in twin pregnancies than in singletons and even higher if a short cervical length is detected in the second trimester. Studies are contradictory regarding the efficacy of a cervical pessary to decrease preterm birth in twin pregnancies and short cervical length. To conduct a systematic review and meta-analysis investigating the efficacy of cervical pessary in prolonging gestation, preventing preterm birth, and reducing adverse neonatal outcomes in twin pregnancies with an asymptomatic short cervix.

Data sources

PubMed, Scopus, Web of Science, and ClinicalTrials.org were searched for randomized controlled trials from inception to June 2023.

Study eligibility criteria

In this study, randomized controlled trials comparing the cervical pessary to expectant management in the pregnant population with twin gestations and asymptomatic short cervix were included.

Methods

The Cochrane risk-of-bias-2 tool for randomized controlled trials was used for the evaluation of the risk of bias in included studies. A meta-analysis was performed by calculating risk ratio and mean difference with their 95% confidence interval using the random effects model or fixed effect model on the basis of heterogeneity and accounting for potential covariates among the included randomized controlled trials.

Results

A total of 6 randomized controlled trials were included in the analysis. Cervical pessary did not significantly increase the gestational age at delivery in twin pregnancies with asymptomatic patients (mean difference, 0.36 weeks [-0.27 to 0.99]; P=.270; I2=72.0%). Moreover, the cervical pessary use did not result in a reduction of spontaneous or all-preterm birth before 37 weeks of gestation (risk ratio, 0.88 [0.77-1.00]; P=.061; I2=0.0%). There was no statistically significant difference in the composite neonatal adverse outcomes (risk ratio, 1.001 [0.86-1.16]; P=.981; I2=20.9%), including early respiratory morbidity, intraventricular hemorrhage, necrotizing enterocolitis, and confirmed sepsis.

Conclusion

The use of cervical pessary in twin pregnancies with asymptomatic short cervix does not seem to be effective in increasing the gestational age at delivery, preventing preterm birth, or reducing adverse neonatal outcomes. This indicates that alternative interventions should be sought for the management of this patient population.

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.

The effectiveness of cervical cerclage in twin pregnancies with a mid-trimester short cervix: A retrospective cohort study

OBJECTIVE

To analyze the effectiveness of cerclage in twin pregnancies with a short cervix.

STUDY DESIGN

Retrospective cohort study performed in two University Institutions in Valencia (Spain) with two different protocols for the management of asymptomatic dichorionic diamniotic twin pregnancies with mid-trimester cervical length ≤ 25 mm: treatment with indomethacin, antibiotics and cerclage (cerclage group) (N = 43) versus expectant management (control group) (N = 37).

RESULTS

The initial cervical length was similar in both groups but detection of a short cervix was performed earlier in the cerclage group (21.6 vs 24.1 weeks, p < 0.001). Women with cerclage had a greater pregnancy latency (12.5 vs. 7.7 weeks, p < 0.001); higher gestational age at delivery (34.1 vs. 31.8 weeks, p < 0.04); less spontaneous preterm birth (SPB) < 28 weeks (11.6 % vs 37.8 %, p < 0.009); higher birthweight (2145 vs 1733 g, p < 0.001); lower birthweight < 1500 g (12.5 % vs 40.0 %, p < 0.001); less admissions to the neonatal intensive care unit (NICU) (24.1 % vs 43.3 %, p < 0.03); shorter stay at NICU (25.6 vs 49.4 days, p < 0.02); lower respiratory distress requiring mechanical ventilation (14.9 % vs 36.5 %, p < 0.02); fewer patent ductus arteriosus (8.9 % vs 26.9 %, p < 0.008); and lower composite adverse neonatal outcome (26.6 % vs. 44.8 %, p < 0.03). Cerclage and gestational age at diagnosis were the only independent predictors of SPB < 32 and < 28 weeks by multivariate analysis. The cumulative data in the literature show promising beneficial effects of cerclage.

CONCLUSION

Our data suggest that cerclage in asymptomatic twin pregnancies with a short cervix may reduce the earliest SPB and may improve neonatal outcome.

Omega-3 fatty acid supply in pregnancy for risk reduction of preterm and early preterm birth

This clinical practice guideline on the supply of the omega-3 docosahexaenoic acid and eicosapentaenoic acid in pregnant women for risk reduction of preterm birth and early preterm birth was developed with support from several medical-scientific organizations, and is based on a review of the available strong evidence from randomized clinical trials and a formal consensus process. We concluded the following. Women of childbearing age should obtain a supply of at least 250 mg/d of docosahexaenoic+eicosapentaenoic acid from diet or supplements, and in pregnancy an additional intake of ≥100 to 200 mg/d of docosahexaenoic acid. Pregnant women with a low docosahexaenoic acid intake and/or low docosahexaenoic acid blood levels have an increased risk of preterm birth and early preterm birth. Thus, they should receive a supply of approximately 600 to 1000 mg/d of docosahexaenoic+eicosapentaenoic acid, or docosahexaenoic acid alone, given that this dosage showed significant reduction of preterm birth and early preterm birth in randomized controlled trials. This additional supply should preferably begin in the second trimester of pregnancy (not later than approximately 20 weeks' gestation) and continue until approximately 37 weeks' gestation or until childbirth if before 37 weeks' gestation. Identification of women with inadequate omega-3 supply is achievable by a set of standardized questions on intake. Docosahexaenoic acid measurement from blood is another option to identify women with low status, but further standardization of laboratory methods and appropriate cutoff values is needed. Information on how to achieve an appropriate intake of docosahexaenoic acid or docosahexaenoic+eicosapentaenoic acid for women of childbearing age and pregnant women should be provided to women and their partners.

Vaginal progesterone for the prevention of recurrent spontaneous preterm birth

After the United States Food and Drug Administration pulled 17-alpha hydroxyprogesterone caproate from the market for its use in prevention of recurrent spontaneous preterm birth, national societies have had mixed recommendations regarding the management of patients with a singleton pregnancy and previous spontaneous preterm birth. Herein we highlight the randomized trial data and translational evidence supporting the use of vaginal progesterone for prevention of recurrent spontaneous preterm birth in singleton pregnancies. Prophylactic vaginal progesterone starting at 16 weeks and 0 days every night should be offered to patients with singletons and previous singleton spontaneous preterm birth regardless of cervical length, and continued along with placement of cerclage if a transvaginal ultrasound cervical length ≤25 mm is detected at <24 weeks.