Vaginal progesterone for the prevention of preterm birth in twin gestations: a randomized placebo-controlled double-blind study

Cervical cerclage versus cervical pessary with or without vaginal progesterone for preterm birth prevention in twin pregnancies and a short cervix: A two-by-two factorial randomised clinical trial

BACKGROUND

Pregnant women with twins and a short cervical length (CL) are at greater risk of preterm birth (PTB). The comparative efficacy of cervical cerclage and cervical pessary with or without additional progesterone to prevent PTB is unknown. We aimed to assess, in women with twin pregnancies and a short CL, the effectiveness of cerclage versus pessary and the additional treatment with 400 mg vaginal progesterone versus no progesterone in preventing PTB.

METHODS AND FINDINGS

This multicenter, two-by-two factorial randomised trial was conducted in 2 hospitals in Ho Chi Minh City, Vietnam. Asymptomatic women with twin pregnancies and a CL ≤28 mm at 16 to 22 gestational weeks were recruited. Between March 2019 and July 2023, we randomised 219 participants (64.4% of the planned sample size) to cerclage plus progesterone (n = 55), Arabin pessary plus progesterone (n = 56), cerclage alone (n = 54) or Arabin pessary alone (n = 54). Primary outcome was any PTB <34 weeks. Following the second interim analysis, the study was terminated due to significantly lower rates of perinatal deaths and deliveries <28 weeks in the cerclage group. The primary outcome occurred in 20 (19.8%) participants receiving cerclage versus 20 (19%) participants receiving pessary (relative risk [RR] 1.04; 95% confidence interval [CI], 0.60 to 1.8). Delivery <28 weeks occurred in 1% versus 8.6% (RR 0.12; 95% CI, 0.01 to 0.52) and perinatal death occurred in 1% versus 5.8% (RR 0.17; 95% CI, 0.05 to 0.62) in the cerclage group and the pessary group, respectively. However, PTB <24 weeks, <32 weeks, and other neonatal outcomes were not significantly different between the 2 groups. For maternal side effects, vaginal discharge was significantly less frequent in the cerclage group. In participants allocated to progesterone, PTB <34 weeks occurred in 19 (18.4%) versus 21 (20.4%) participants who did not have progesterone (RR 0.90; 95% CI, 0.52 to 1.6).

CONCLUSIONS

In this prematurely halted study on pregnant women with twins and a CL ≤28 mm, cerclage and cervical pessary were comparably effective on PTB <34 weeks prevention. However, compared to pessary, cerclage was associated with significantly lower rates of PTB <28 weeks and perinatal mortality. ClinicalTrials.gov Registration: NCT03863613 (https://clinicaltrials.gov/study/NCT03863613).

Prognostic value of cervical length for spontaneous preterm birth in asymptomatic women with twin pregnancy: meta-analysis of individual participant data

Objective

To quantify the prognostic value of mid-trimester cervical length for spontaneous preterm birth in asymptomatic women with twin pregnancy and to assess whether other factors may modify any association.

Designs

A two stage meta-analysis of individual participant data in a Cox proportional hazard model was performed using cervical length as a continuous variable.

Data sources

Medline, Embase, Cochrane, and LILACS, among others, were searched to identify eligible studies; the search was from 1 January 2000 to 30 September 2020. Risk of bias was assessed with the QUIPS tool. Studies were from eight countries between 2001 and 2018.

Eligibility criteria

Individual participant data were sought for eligible studies that reported mid-trimester (defined between 16 and 26 weeks) transvaginal sonographic cervical length and also gestational age at birth in asymptomatic women with twin pregnancy. The primary outcome was spontaneous preterm birth before 37 weeks.

Results

Among 29 eligible studies, authors of 17 studies provided individual participant data for 6437 women with a twin pregnancy (69.1% of individual participant data). Mean cervical length measurement was 39 mm (SD=9, range 1-74 mm). 2889 women (44.9%) delivered before 37 weeks' gestation, and 934 (14.9%) delivered before 34 weeks. Each 1 mm increase in cervical length was associated with a 4.0% reduction in the rate of spontaneous preterm birth before 37 weeks (hazard ratio 0.96 (95% confidence interval 0.95 to 0.97)), and a 6.8% reduction in the rate of spontaneous preterm birth before 34 weeks' gestation (0.93 (0.92 to 0.95)). The prognostic value remained stable in models adjusting for different sets of variables.

Conclusion

The prognostic value of cervical length for spontaneous preterm birth in twin pregnancy is on a continuous scale. No specific cervical length has been identified that can reliably predict or exclude all spontaneous preterm births.

Study registration

CRD42020146987.

Vaginal micronised progesterone for the prevention of hypertensive disorders of pregnancy: A systematic review and meta-analysis

BACKGROUND

Treatment with vaginal progesterone reduces the risk of miscarriage and preterm birth in selected high-risk women. The hypothesis that vaginal progesterone can reduce the risk of hypertensive disorders of pregnancy (HDP) is unexplored.

OBJECTIVES

To summarise the evidence on the effectiveness of vaginal progesterone to reduce the risk of HDP.

SEARCH STRATEGY

We searched Embase (OVID), MEDLINE (OVID), PubMed, CENTRAL and clinicaltrials.gov from inception until 20 June 2023.

SELECTION CRITERIA

We included placebo-controlled randomised trials (RCTs) of vaginal progesterone for the prevention or treatment of any pregnancy complications.

DATA COLLECTION AND ANALYSIS

We extracted absolute event numbers for HDP and pre-eclampsia in women receiving vaginal progesterone or placebo, and meta-analysed the data with a random effects model. We appraised the certainty of the evidence using GRADE methodology.

MAIN RESULTS

The quantitative synthesis included 11 RCTs, of which three initiated vaginal progesterone in the first trimester, and eight in the second or third trimesters. Vaginal progesterone started in the first trimester of pregnancy lowered the risk of any HDP (risk ratio [RR] 0.71, 95% confidence interval [CI] 0.53-0.93, 2 RCTs, n = 4431 women, I2 = 0%; moderate-certainty evidence) and pre-eclampsia (RR 0.61, 95% CI 0.41-0.92, 3 RCTs, n = 5267 women, I2 = 0%; moderate-certainty evidence) when compared with placebo. Vaginal progesterone started in the second or third trimesters was not associated with a reduction in HDP (RR 1.19, 95% CI 0.67-2.12, 3 RCTs, n = 1602 women, I2 = 9%; low-certainty evidence) or pre-eclampsia (RR 0.97, 95% CI 0.71-1.31, 5 RCTs, n = 4274 women, I2 = 0%; low-certainty evidence).

CONCLUSIONS

Our systematic review found first-trimester initiated vaginal micronised progesterone may reduce the risk of HDP and pre-eclampsia.

Pregnant Populations which Benefit from Vaginal Progesterone for Preventing Preterm Birth at <34 Weeks and Neonatal Morbidities: A Systematic Review and Meta-analysis

This study aimed to assess vaginal progesterone's effect on different populations and performed comparation between women with varied risk factors. Embase, PubMed, Cochrane library (CENTRAL) were searched without restriction to language up to February 25, 2021. Randomized controlled trials (RCTs) assessing vaginal progesterone administered to women at risk of preterm birth at <37 weeks. Two reviewers independently extracted data, and pooled relative risk (RR) with 95% confidence intervals (CIs) was calculated as well. Women with short cervix have a significantly lower risk of preterm birth at <34 weeks (pooled RR = 0.65; 95% CI: 0.55-0.77; I 2 = 0; p < 0.001; nine studies) and some neonatal morbidities; interaction tests showed that effect of vaginal progesterone differs significantly between women with short cervix and those with other risk factors (history of preterm birth, exclusive twin gestation, and vaginal bleeding). Evidences of this study showed that singleton gestations, as well as women with short cervix, benefit from vaginal progesterone in preventing preterm birth at <34 weeks and some neonatal morbidities. Women with short cervix are populations who benefit the most among other risk populations. KEY POINTS: · Vaginal progesterone reduces preterm birth and neonatal morbidities.. · Vaginal progesterone effects on some specific populations.. · Women with short cervix benefit the most..

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

OBJECTIVE

To evaluate the efficacy of vaginal progesterone for the prevention of preterm birth and adverse perinatal outcomes in twin gestations.

DATA SOURCES

MEDLINE, Embase, LILACS, and CINAHL (from their inception to January 31, 2023), Cochrane databases, Google Scholar, bibliographies, and conference proceedings.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials that compared vaginal progesterone to placebo or no treatment in asymptomatic women with a twin gestation.

METHODS

The systematic review was conducted according to the Cochrane Handbook for Systematic Reviews of Interventions. The primary outcome was preterm birth <34 weeks of gestation. Secondary outcomes included adverse perinatal outcomes. Pooled relative risks with 95% confidence intervals were calculated. We assessed the risk of bias in each included study, heterogeneity, publication bias, and quality of evidence, and performed subgroup and sensitivity analyses.

RESULTS

Eleven studies (3401 women and 6802 fetuses/infants) fulfilled the inclusion criteria. Among all twin gestations, there were no significant differences between the vaginal progesterone and placebo or no treatment groups in the risk of preterm birth <34 weeks (relative risk, 0.99; 95% confidence interval, 0.84-1.17; high-quality evidence), <37 weeks (relative risk, 0.99; 95% confidence interval, 0.92-1.06; high-quality evidence), and <28 weeks (relative risk, 1.00; 95% confidence interval, 0.64-1.55; moderate-quality evidence), and spontaneous preterm birth <34 weeks of gestation (relative risk, 0.97; 95% confidence interval, 0.80-1.18; high-quality evidence). Vaginal progesterone had no significant effect on any of the perinatal outcomes evaluated. Subgroup analyses showed that there was no evidence of a different effect of vaginal progesterone on preterm birth <34 weeks of gestation related to chorionicity, type of conception, history of spontaneous preterm birth, daily dose of vaginal progesterone, and gestational age at initiation of treatment. The frequencies of preterm birth <37, <34, <32, <30, and <28 weeks of gestation and adverse perinatal outcomes did not significantly differ between the vaginal progesterone and placebo or no treatment groups in unselected twin gestations (8 studies; 3274 women and 6548 fetuses/infants). Among twin gestations with a transvaginal sonographic cervical length <30 mm (6 studies; 306 women and 612 fetuses/infants), vaginal progesterone was associated with a significant decrease in the risk of preterm birth occurring at <28 to <32 gestational weeks (relative risks, 0.48-0.65; moderate- to high-quality evidence), neonatal death (relative risk, 0.32; 95% confidence interval, 0.11-0.92; moderate-quality evidence), and birthweight <1500 g (relative risk, 0.60; 95% confidence interval, 0.39-0.88; high-quality evidence). Vaginal progesterone significantly reduced the risk of preterm birth occurring at <28 to <34 gestational weeks (relative risks, 0.41-0.68), composite neonatal morbidity and mortality (relative risk, 0.59; 95% confidence interval, 0.33-0.98), and birthweight <1500 g (relative risk, 0.55; 95% confidence interval, 0.33-0.94) in twin gestations with a transvaginal sonographic cervical length ≤25 mm (6 studies; 95 women and 190 fetuses/infants). The quality of evidence was moderate for all these outcomes.

CONCLUSION

Vaginal progesterone does not prevent preterm birth, nor does it improve perinatal outcomes in unselected twin gestations, but it appears to reduce the risk of preterm birth occurring at early gestational ages and of neonatal morbidity and mortality in twin gestations with a sonographic short cervix. However, more evidence is needed before recommending this intervention to this subset of patients.

Screening and Prevention of Preterm Birth in Twin Pregnancies

Twins represent 3.2% of all live births. However, they account for 20% of all preterm deliveries, 60% delivering <37 weeks, 10.7% <32 weeks, and 5 times higher risk of infant death. Risk factors for preterm birth (PTB) include the history of preterm delivery, monochorionic twins, short cervical length, and cervical surgery. Transvaginal cervical length <24 weeks is the best tool to predict PTB. Only vaginal progesterone in women with transvaginal cervical length <25 mm and physical exam indicated cerclage in women with cervical dilation >1 cm have shown a significant decrease in PTB and improvement in neonatal outcomes.

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.

Prevention of Preterm Birth by Cervical Pessary Combined with Vaginal Progesterone: a Systematic Review and Meta-analysis with Trial Sequential Analysis

This study was to assess the effectiveness of cervical pessary combined with vaginal progesterone for the prevention of preterm birth (PTB). Ten studies about singleton [five randomized controlled trials (RCTs), vs vaginal progesterone; four cohorts, vs vaginal progesterone; two cohorts, vs cervical cerclage + vaginal progesterone] and two cohort studies about multiple pregnancies (vs vaginal progesterone) were included after searching electronic databases. For singleton pregnancies, the meta-analysis of three non-RCTs [relative risk (RR) = 0.41, p = 0.001] or total trials in non-Asian country (RR = 0.56, p = 0.03) revealed that compared with vaginal progesterone alone, cervical pessary + vaginal progesterone treatment had significant effectiveness on preventing PTB < 34 weeks, but not for five RCTs; meta-analysis of two trials showed that cervical pessary + vaginal progesterone had no significant prevention effects of PTB compared with cervical cerclage + vaginal progesterone. For multiple pregnancies, meta-analysis of two trials showed that compared with vaginal progesterone, cervical pessary + vaginal progesterone treatment increased neonatal birth weight (standardized mean difference = 0.50, p = 0.01). Trial sequential analysis implied additional studies were required. Four studies vs other controls (pessary, three-combined, tocolysis, conservative or no treatment; one study, each) were selected for systematic review. In conclusion, cervical pessary combined with vaginal progesterone may be safe and effective to prevent PTB in singleton pregnancies and increase neonatal birth weight in the multiple pregnancies compared with vaginal progesterone alone.

Pessary or progesterone to prevent preterm birth in women with short cervical length: protocol of the 4-6 year follow-up of a randomised controlled trial (Quadruple-P)

INTRODUCTION

Vaginal progesterone and a cervical pessary are both interventions that are investigated for the prevention of preterm birth (PTB). Thus far, beneficial or harmful effects of these interventions on long-term child health and development are described, but evidence is not robust enough to draw firm conclusions. With this follow-up study, we intent to investigate if progesterone or a pessary is superior for the prevention of PTB considering the child's health at 4-6 years of corrected age.

METHODS AND ANALYSIS

This study is a follow-up study of the Quadruple-P trial; a multicentre, randomised clinical trial (NL42926.018.13, Eudractnumber 2013-002884-24) which randomises women with an asymptomatic midtrimester short cervix to daily progesterone or a pessary for the prevention of PTB. All children born to mothers who participated in the Quadruple-P study (n=628 singletons and n=332 multiples) will be eligible for follow-up at 4-6 years of corrected age. Children will be assessed using parental questionnaires. Main outcomes are child (neuro)development and behaviour. Other outcomes include child mortality, growth and general health. A composite of adverse child outcomes will be compared between the progesterone and pessary groups reporting OR and the corresponding 95% CI. Analyses will be performed separately for singletons and multiples and using the intention-to-treat approach.

ETHICS AND DISSEMINATION

The Medical Research Ethics Committee from Amsterdam UMC confirmed that de Medical Research Involving Human Subjects Act (WMO) did not apply to our study (W20_481 #20.531). Results will be published in a peer-reviewed journal and shared with stakeholders and participants. This protocol is published before analysis of the results.

TRIAL REGISTRATION NUMBER

Dutch Trial Register (NL9646).

Timing of Delivery for Twins With Growth Discordance and Growth Restriction: An Individual Participant Data Meta-analysis

OBJECTIVE

First, to evaluate the risks of stillbirth and neonatal death by gestational age in twin pregnancies with different levels of growth discordance and in relation to small for gestational age (SGA), and on this basis to establish optimal gestational ages for delivery. Second, to compare these optimal gestational ages with previously established optimal delivery timing for twin pregnancies not complicated by fetal growth restriction, which, in a previous individual patient meta-analysis, was calculated at 37 0/7 weeks of gestation for dichorionic pregnancies and 36 0/7 weeks for monochorionic pregnancies.

DATA SOURCES

A search of MEDLINE, EMBASE, ClinicalTrials.gov, and Ovid between 2015 and 2018 was performed of cohort studies reporting risks of stillbirth and neonatal death in twin pregnancies from 32 to 41 weeks of gestation. Studies from a previous meta-analysis using a similar search strategy (from inception to 2015) were combined. Women with monoamniotic twin pregnancies were excluded.

METHODS OF STUDY SELECTION

Overall, of 57 eligible studies, 20 cohort studies that contributed original data reporting on 7,474 dichorionic and 2,281 monochorionic twin pairs.

TABULATION, INTEGRATION, AND RESULTS

We performed an individual participant data meta-analysis to calculate the risk of perinatal death (risk difference between prospective stillbirth and neonatal death) per gestational week. Analyses were stratified by chorionicity, levels of growth discordance, and presence of SGA in one or both twins. For both dichorionic and monochorionic twins, the absolute risks of stillbirth and neonatal death were higher when one or both twins were SGA and increased with greater levels of growth discordance. Regardless of level of growth discordance and birth weight, perinatal risk balanced between 36 0/7-6/7 and 37 0/7-6/7 weeks of gestation in both dichorionic and monochorionic twin pregnancies, with likely higher risk of stillbirth than neonatal death from 37 0/7-6/7 weeks onward.

CONCLUSION

Growth discordance or SGA is associated with higher absolute risks of stillbirth and neonatal death. However, balancing these two risks, we did not find evidence that the optimal timing of delivery is changed by the presence of growth disorders alone.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, CRD42018090866.

Prevention of preterm birth in twin pregnancies

Twins represent 3.2% of all live births; however, they account for 20.0% of all preterm deliveries, with 60.0% and 10.7% of twins delivered before 37 and 32 weeks' gestation, respectively. Twin pregnancies have 5 times higher risk of early neonatal and infant death related to prematurity. Monochorionic twins have a higher incidence of both indicated and spontaneous preterm delivery than dichorionic twins. Transvaginal ultrasound of the cervical length before 24 weeks' gestation is the best tool to predict preterm birth, independent of other risk factors. Among all evaluated therapies to decrease or prevent preterm birth in twin pregnancies, the use of vaginal progesterone in women with a transvaginal cervical length of <25 mm decreased neonatal morbidity, and physical examination-indicated cerclage in women with a cervical dilation of >1 cm showed a significant decrease in preterm birth at different gestational ages and perinatal mortality.

Interventions to reduce preterm birth and stillbirth, and improve outcomes for babies born preterm in low- and middle-income countries: A systematic review

BACKGROUND

Reducing preterm birth and stillbirth and improving outcomes for babies born too soon is essential to reduce under-5 mortality globally. In the context of a rapidly evolving evidence base and problems with extrapolating efficacy data from high- to low-income settings, an assessment of the evidence for maternal and newborn interventions specific to low- and middle-income countries (LMICs) is required.

METHODS

A systematic review of the literature was done. We included all studies performed in LMICs since the Every Newborn Action Plan, between 2013 - 2018, which reported on interventions where the outcome assessed was reduction in preterm birth or stillbirth incidence and/or a reduction in preterm infant neonatal mortality. Evidence was categorised according to maternal or neonatal intervention groups and a narrative synthesis conducted.

RESULTS

179 studies (147 primary evidence studies and 32 systematic reviews) were identified in 82 LMICs. 81 studies reported on maternal interventions and 98 reported on neonatal interventions. Interventions in pregnant mothers which resulted in significant reductions in preterm birth and stillbirth were (i) multiple micronutrient supplementation and (ii) enhanced quality of antenatal care. Routine antenatal ultrasound in LMICs increased identification of fetal antenatal conditions but did not reduce stillbirth or preterm birth due to the absence of services to manage these diagnoses. Interventions in pre-term neonates which improved their survival included (i) feeding support including probiotics and (ii) thermal regulation. Improved provision of neonatal resuscitation did not improve pre-term mortality rates, highlighting the importance of post-resuscitation care. Community mobilisation, for example through community education packages, was found to be an effective way of delivering interventions.

CONCLUSIONS

Evidence supports the implementation of several low-cost interventions with the potential to deliver reductions in preterm birth and stillbirth and improve outcomes for preterm babies in LMICs. These, however, must be complemented by overall health systems strengthening to be effective. Quality improvement methodology and learning health systems approaches can provide important means of understanding and tackling implementation challenges within local contexts. Further pragmatic efficacy trials of interventions in LMICs are essential, particularly for interventions not previously tested in these contexts.

Prediction and Prevention of Spontaneous Preterm Birth: ACOG Practice Bulletin, Number 234

Preterm birth is among the most complex and important challenges in obstetrics. Despite decades of research and clinical advancement, approximately 1 in 10 newborns in the United States is born prematurely. These newborns account for approximately three-quarters of perinatal mortality and more than one half of long-term neonatal morbidity, at significant social and economic cost (1-3). Because preterm birth is the common endpoint for multiple pathophysiologic processes, detailed classification schemes for preterm birth phenotype and etiology have been proposed (4, 5). In general, approximately one half of preterm births follow spontaneous preterm labor, about a quarter follow preterm prelabor rupture of membranes (PPROM), and the remaining quarter of preterm births are intentional, medically indicated by maternal or fetal complications. There are pronounced racial disparities in the preterm birth rate in the United States. The purpose of this document is to describe the risk factors, screening methods, and treatments for preventing spontaneous preterm birth, and to review the evidence supporting their roles in clinical practice. This Practice Bulletin has been updated to include information on increasing rates of preterm birth in the United States, disparities in preterm birth rates, and approaches to screening and prevention strategies for patients at risk for spontaneous preterm birth.

Role of progesterone, cerclage and pessary in preventing preterm birth in twin pregnancies: A systematic review and network meta-analysis

OBJECTIVE

To determine the role of progesterone, pessary and cervical cerclage in reducing the risk of (preterm birth) PTB in twin pregnancies and compare these interventions using pairwise and network meta-analysis.

STUDY DESIGN

Medline, Embase, CINAHL and Cochrane databases were explored. The inclusion criteria were studies in which twin pregnancies were randomized to an intervention for the prevention of PTB (any type of progesterone, cervical cerclage, cervical pessary, or any combination of these) or to a control group (e.g. placebo or treatment as usual). Interventions of interest were either progesterone [vaginal or oral natural progesterone or intramuscular 17a-hydroxyprogesterone caproate (17-OHPC)], cerclage (McDonald or Shirodkar), or cervical pessary. The primary outcome was PTB < 34 weeks of gestation. Both primary and secondary outcomes were explored in an unselected population of twin pregnancies and in women at higher risk of PTB (defined as those with cervical length <25 mm). Random-effect head-to-head and a multiple-treatment meta-analyses were used to analyze the data and results expressed as risk ratios.

RESULTS

26 studies were included in the meta-analysis. When considering an unselected population of twin pregnancies, vaginal progesterone, intra-muscular17-OHPC or pessary did not reduce the risk of PTB < 34 weeks of gestation (all p > 0.05). When stratifying the analysis for spontaneous PTB, neither pessary, vaginal or intramuscular 17-OHPC were associated with a significant reduction in the risk of PTB compared to controls (all p > 0.05), while there was no study on cerclage which explored this outcome in an unselected population of twin pregnancies. When considering twin pregnancies with short cervical length (≤25 mm), there was no contribution of either pessary, vaginal progesterone, intra-muscular 17-OHPC or cerclage in reducing the risk of overall PTB < 34 weeks of gestation.

CONCLUSIONS

Cervical pessary, progesterone and cerclage do not show a significant effect in reducing the rate of PTB or perinatal morbidity in twins, either when these interventions are applied to an unselected population of twins or in pregnancies with a short cervix.

Evaluating Progestogens for Preventing Preterm birth International Collaborative (EPPPIC): meta-analysis of individual participant data from randomised controlled trials

BACKGROUND

Preterm birth is a global health priority. Using a progestogen during high-risk pregnancy could reduce preterm birth and adverse neonatal outcomes.

METHODS

We did a systematic review of randomised trials comparing vaginal progesterone, intramuscular 17-hydroxyprogesterone caproate (17-OHPC), or oral progesterone with control, or with each other, in asymptomatic women at risk of preterm birth. We identified published and unpublished trials that completed primary data collection before July 30, 2016, (12 months before data collection began), by searching MEDLINE, Embase, CINAHL, the Maternity and Infant Care Database, and relevant trial registers between inception and July 30, 2019. Trials of progestogen to prevent early miscarriage or immediately-threatened preterm birth were excluded. Individual participant data were requested from investigators of eligible trials. Outcomes included preterm birth, early preterm birth, and mid-trimester birth. Adverse neonatal sequelae associated with early births were assessed using a composite of serious neonatal complications, and individually. Adverse maternal outcomes were investigated as a composite and individually. Individual participant data were checked and risk of bias assessed independently by two researchers. Primary meta-analyses used one-stage generalised linear mixed models that incorporated random effects to allow for heterogeneity across trials. This meta-analysis is registered with PROSPERO, CRD42017068299.

FINDINGS

Initial searches identified 47 eligible trials. Individual participant data were available for 30 of these trials. An additional trial was later included in a targeted update. Data were therefore available from a total of 31 trials (11 644 women and 16185 offspring). Trials in singleton pregnancies included mostly women with previous spontaneous preterm birth or short cervix. Preterm birth before 34 weeks was reduced in such women who received vaginal progesterone (nine trials, 3769 women; relative risk [RR] 0·78, 95% CI 0·68-0·90), 17-OHPC (five trials, 3053 women; 0·83, 0·68-1·01), and oral progesterone (two trials, 181 women; 0·60, 0·40-0·90). Results for other birth and neonatal outcomes were consistently favourable, but less certain. A possible increase in maternal complications was suggested, but this was uncertain. We identified no consistent evidence of treatment interaction with any participant characteristics examined, although analyses within subpopulations questioned efficacy in women who did not have a short cervix. Trials in multifetal pregnancies mostly included women without additional risk factors. For twins, vaginal progesterone did not reduce preterm birth before 34 weeks (eight trials, 2046 women: RR 1·01, 95% CI 0·84-1·20) nor did 17-OHPC for twins or triplets (eight trials, 2253 women: 1·04, 0·92-1·18). Preterm premature rupture of membranes was increased with 17-OHPC exposure in multifetal gestations (rupture <34 weeks RR 1·59, 95% CI 1·15-2·22), but we found no consistent evidence of benefit or harm for other outcomes with either vaginal progesterone or 17-OHPC.

INTERPRETATION

Vaginal progesterone and 17-OHPC both reduced birth before 34 weeks' gestation in high-risk singleton pregnancies. Given increased underlying risk, absolute risk reduction is greater for women with a short cervix, hence treatment might be most useful for these women. Evidence for oral progesterone is insufficient to support its use. Shared decision making with woman with high-risk singleton pregnancies should discuss an individual's risk, potential benefits, harms and practicalities of intervention. Treatment of unselected multifetal pregnancies with a progestogen is not supported by the evidence.

FUNDING

Patient-Centered Outcomes Research Institute.

Early vaginal progesterone versus placebo in twin pregnancies for the prevention of spontaneous preterm birth: a randomized, double-blind trial

BACKGROUND

In women with a singleton pregnancy and sonographic short cervix in midgestation, vaginal administration of progesterone reduces the risk of early preterm birth and improves neonatal outcomes without any demonstrable deleterious effects on childhood neurodevelopment. In women with twin pregnancies, the rate of spontaneous early preterm birth is 10 times higher than that in singletons, and in this respect, all twins are at an increased risk of preterm birth. However, 6 trials in unselected twin pregnancies reported that vaginal administration of progesterone from midgestation had no significant effect on the incidence of early preterm birth. Such apparent lack of effectiveness of progesterone in twins may be due to inadequate dosage or treatment that is started too late in pregnancy.

OBJECTIVE

The early vaginal progesterone for the prevention of spontaneous preterm birth in twins, a randomized, placebo-controlled, double-blind trial, was designed to test the hypothesis that among women with twin pregnancies, vaginal progesterone at a dose of 600 mg per day from 11 to 14 until 34 weeks' gestation, as compared with placebo, would result in a significant reduction in the incidence of spontaneous preterm birth between 24⁺⁰ and 33⁺⁶ weeks.

STUDY DESIGN

The trial was conducted at 22 hospitals in England, Spain, Bulgaria, Italy, Belgium, and France. Women were randomly assigned in a 1:1 ratio to receive either progesterone or placebo, and in the random-sequence generation, there was stratification according to the participating center. The primary outcome was spontaneous birth between 24⁺⁰ and 33⁺⁶ weeks' gestation. Statistical analyses were performed on an intention-to-treat basis. Logistic regression analysis was used to determine the significance of difference in the incidence of spontaneous birth between 24⁺⁰ and 33⁺⁶ weeks' gestation between the progesterone and placebo groups, adjusting for the effect of participating center, chorionicity, parity, and method of conception. Prespecified tests of treatment interaction effects with chorionicity, parity, method of conception, compliance, and cervical length at recruitment were performed. A post hoc analysis using mixed-effects Cox regression was used for further exploration of the effect of progesterone on preterm birth.

RESULTS

We recruited 1194 women between May 2017 and April 2019; 21 withdrew consent and 4 were lost to follow-up, which left 582 in the progesterone group and 587 in the placebo group. Adherence was good, with reported intake of ≥80% of the required number of capsules in 81.4% of the participants. After excluding births before 24 weeks and indicated deliveries before 34 weeks, spontaneous birth between 24⁺⁰ and 33⁺⁶ weeks occurred in 10.4% (56/541) of participants in the progesterone group and in 8.2% (44/538) in the placebo group (odds ratio in the progesterone group, adjusting for the effect of participating center, chorionicity, parity, and method of conception, 1.35; 95% confidence interval, 0.88-2.05; P=.17). There was no evidence of interaction between the effects of treatment and chorionicity (P=.28), parity (P=.35), method of conception (P=.56), and adherence (P=.34); however, there was weak evidence of an interaction with cervical length (P=.08) suggestive of harm to those with a cervical length of ≥30 mm (odds ratio, 1.61; 95% confidence interval, 1.01-2.59) and potential benefit for those with a cervical length of <30 mm (odds ratio, 0.56; 95% confidence interval, 0.20-1.60). There was no evidence of difference between the 2 treatment groups for stillbirth or neonatal death, neonatal complications, neonatal therapy, and poor fetal growth. In the progesterone group, 1.4% (8/582) of women and 1.9% (22/1164) of fetuses experienced at least 1 serious adverse event; the respective numbers for the placebo group were 1.2% (7/587) and 3.2% (37/1174) (P=.80 and P=.06, respectively). In the post hoc time-to-event analysis, miscarriage or spontaneous preterm birth between randomization and 31⁺⁶ weeks' gestation was reduced in the progesterone group relative to the placebo group (hazard ratio, 0.23; 95% confidence interval, 0.08-0.69).

CONCLUSION

In women with twin pregnancies, universal treatment with vaginal progesterone did not reduce the incidence of spontaneous birth between 24⁺⁰ and 33⁺⁶ weeks' gestation. Post hoc time-to-event analysis led to the suggestion that progesterone may reduce the risk of spontaneous birth before 32 weeks' gestation in women with a cervical length of <30 mm, and it may increase the risk for those with a cervical length of ≥30 mm.

Cervical Pessary Plus Progesterone for Twin Pregnancy with Short Cervix Compared to Unselected and Non-Treated Twin Pregnancy: A Historical Equivalence Cohort Study (EPM Twin Pessary Study)

OBJECTIVE

 The present study aims to determine if the use of cervical pessary plus progesterone in short-cervix (≤ 25 mm) dichorionic-diamniotic (DC-DA) twin pregnancies is equivalent to the rate of preterm births (PBs) with no intervention in unselected DC-DA twin pregnancies.

METHODS

 A historical cohort study was performed between 2010 and 2018, including a total of 57 pregnant women with DC-DA twin pregnancies. The women admitted from 2010 to 2012 (n = 32) received no treatment, and were not selected by cervical length (Non-Treated group, NTG), whereas those admitted from 2013 to 2018 (n = 25), were routinely submitted to cervical pessary plus progesterone after the diagnosis of short cervix from the 18th to the 27th weeks of gestation (Pessary-Progesterone group, PPG). The primary outcome analyzed was the rate of PBs before 34 weeks.

RESULTS

 There were no statistical differences between the NTG and the PPG regarding PB < 34 weeks (18.8% versus 40.0% respectively; p = 0.07) and the mean birthweight of the smallest twin (2,037 ± 425 g versus 2,195 ± 665 g; p = 0.327). The Kaplan-Meyer Survival analysis was performed, and there were no differences between the groups before 31.5 weeks. Logistic regression showed that a previous PB (< 37 weeks) presented an odds ratio (OR) of 15.951 (95% confidence interval [95%CI]: 1.294-196.557; p = 0.031*) for PB < 34 weeks in the PPG.

CONCLUSION

 In DC-DA twin pregnancies with a short cervix, (which means a higher risk of PB), the treatment with cervical pessary plus progesterone could be considered equivalent in several aspects related to PB in the NTG, despite the big difference between these groups.

Association between chorionicity and preterm birth in twin pregnancies: a systematic review involving 29 864 twin pregnancies

BACKGROUND

The perinatal mortality and morbidity among twins vary by chorionicity. Although it is considered that monochorionicity is associated with an increased risk of preterm birth in twin pregnancies, no systematic review exists evaluating this association.

OBJECTIVES

This systematic review was undertaken to assess the association between preterm birth and chorionicity in twin pregnancies.

SEARCH STRATEGY

We searched the electronic databases from January 1990 to July 2019 without language restrictions.

SELECTION CRITERIA

All studies on twin pregnancies where chorionicity and preterm birth were evaluated were included.

DATA COLLECTION AND ANALYSIS

Findings are reported as odds ratios with 95% confidence intervals. The estimates are pooled using random-effects meta-analysis.

MAIN RESULTS

From 13 156 citations, we included 39 studies (29 864 pregnancies). Monochorionicity was significantly associated with increased risk of preterm birth at ≤28, ≤32, ≤34 and <37 weeks in women asymptomatic and symptomatic for preterm labour (odds ratio [OR] 2.14, 95% CI 1.52-3.02, I²  = 46%, OR 1.55, 95% CI 1.27-1.89 I²  = 68%, OR 1.47, 95% CI 1.27-1.69, I²  = 60%, OR 1.66, 95% CI 1.43-1.93, I²  = 65%, respectively). Among those asymptomatic for preterm labour, significantly increased odds of preterm birth were seen for monochorionicity at gestations ≤34 weeks (OR 1.85, 95% CI 1.42-2.40, I²  = 25%) and <37 weeks (OR 1.75, 95% CI 1.22-2.53, I²  = 61%). Sensitivity analysis showed significantly increased odds of spontaneous preterm birth at ≤34 and <37 weeks for monochorionicity (OR 1.25, 95% CI 1.01-1.55, I²  = 0% and OR 1.41, 95% CI 1.13-1.78, I²  = 0%).

CONCLUSIONS

Monochorionicity is significantly associated with preterm birth at all gestations.

TWEETABLE ABSTRACT

In twin pregnancies, monochorionicity is associated with an increased risk of preterm birth at all gestations.

The effect of early administration of rectal progesterone in IVF/ICSI twin pregnancies on the preterm birth rate: a randomized trial

BACKGROUND

The rate of multiple pregnancies in IVF/ICSI ranges from 20 to 30%. The incidence of preterm birth in multiple pregnancies is as high as 60% and is even higher in pregnancies conceived after IVF & ICSI. The effect of progesterone on prevention of preterm birth in twins is controversial. Our group has proven a positive effect in reduction of preterm birth, by starting progesterone from the mid-trimester, in exclusively IVF/ICSI singleton pregnancies but not twins. The purpose of our current study was to explore the effect of earlier administration of natural progesterone, in IVF/ICSI twin pregnancies starting at 11-14 weeks for prevention of preterm birth.

METHODS

This is a double-blind, placebo controlled, single center, randomized clinical trial. Women with dichorionic twin gestations, having an IVF/ICSI trial were randomized to receive natural rectal progesterone (800 mg daily) vs placebo, starting early from 11 to 14 weeks. They also received oral and vaginal antimicrobial agents as part of our routine treatment for vaginitis and urinary tract infection. They were randomized regardless of cervical length and had no previous history of preterm birth or known Mullerian anomalies. The primary outcome was spontaneous preterm birth rate before 37 weeks. The secondary outcome was; spontaneous preterm birth before 34, 32, 28 weeks and neonatal outcome.

RESULTS

A total of 203 women were randomized to both groups, final analysis included 199 women as 4 were lost to follow up. The base line characteristics as well as gestational age at delivery were not significantly different between the study and the placebo group (34.7 ± 3.6 vs 34.5 ± 4.5, P = 0.626). Progesterone administration was not associated with a significant decrease in the spontaneous preterm birth rates before 37 weeks (73.5% vs 68%, P = 0.551), before 34 (20.6% vs 21.6%, P = 0.649), before 32 (8.8% vs 12.4%, P = 0.46) & before 28 (4.9% vs 3.1%, P = 0.555) weeks.

CONCLUSIONS

Rectal natural progesterone starting from the first trimester in IVF/ICSI twin pregnancies did not reduce spontaneous preterm birth.

TRIAL REGISTRATION

The trial was registered on 31 January 2014 at www.ISRCTN.com, number 69810120.

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.

Prenatal administration of progestogens for preventing spontaneous preterm birth in women with a multiple pregnancy

BACKGROUND

Multiple pregnancy is a strong risk factor for preterm birth, and more than 50% of women with a twin pregnancy will give birth prior to 37 weeks' gestation. Infants born preterm are recognised to be at increased risk of many adverse health outcomes, contributing to more than half of overall perinatal mortality. Progesterone is produced naturally in the body and has a role in maintaining pregnancy, although it is not clear whether administering progestogens to women with multiple pregnancy at high risk of early birth is effective and safe. Since publication of this new review in Issue 10, 2017, we have now moved one study (El-Refaie 2016) from included to studies awaiting classification, pending clarification about the study data.

OBJECTIVES

To assess the benefits and harms of progesterone administration for the prevention of preterm birth in women with a multiple pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (1 November 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials examining the administration of a progestogen by any route for the prevention of preterm birth in women with multiple pregnancy. We did not include quasi-randomised or cross-over studies.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed reports identified by the search for eligibility, extracted data, assessed risk of bias and graded the quality of the evidence.

MAIN RESULTS

We included 16 trials, which all compared either vaginal or intramuscular (IM) progesterone with a placebo or no treatment, and involved a total of 4548 women. The risk of bias for the majority of included studies was low, with the exception of three studies that had inadequate blinding, or significant loss to follow-up or both, or were not reported well enough for us to make a judgement. We graded the evidence low to high quality, with downgrading for statistical heterogeneity, design limitations in some of the studies contributing data, and imprecision of the effect estimate. 1 IM progesterone versus no treatment or placebo More women delivered at less than 34 weeks' gestation in the IM progesterone group compared with placebo (risk ratio (RR) 1.54, 95% confidence interval (CI) 1.06 to 2.26; women = 399; studies = 2; low-quality evidence). Although the incidence of perinatal death in the progesterone group was higher, there was considerable uncertainty around the effect estimate and high heterogeneity between studies (average RR 1.45, 95% CI 0.60 to 3.51; infants = 3089; studies = 6; I2 = 71%; low-quality evidence). No studies reported maternal mortality or major neurodevelopmental disability at childhood follow-up. There were no clear group differences found in any of the other maternal or infant outcomes (preterm birth less than 37 weeks (RR 1.05, 95% CI 0.98 to 1.13; women = 2010; studies = 5; high-quality evidence); preterm birth less than 28 weeks (RR 1.08, 95% CI 0.75 to 1.55; women = 1920; studies = 5; moderate-quality evidence); infant birthweight less than 2500 g (RR 0.99, 95% CI 0.90 to 1.08; infants = 4071; studies = 5; I2 = 76%, moderate-quality evidence)). No childhood outcomes were reported in the trials. 2 Vaginal progesterone versus no treatment or placebo by dose There were no clear group differences in incidence of preterm birth before 34 weeks (average RR 0.90, 95% CI 0.66 to 1.23; women = 1503; studies = 5; I2 = 36%; low-quality evidence). Although fewer births before 34 weeks appeared to occur in the progesterone group, the CIs crossed the line of no effect. Incidence of perinatal death was higher in the progesterone group, although there was considerable uncertainty in the effect estimate and the quality of the evidence was low for this outcome (RR 1.23, 95% CI 0.74 to 2.06; infants = 2287; studies = 3; low-quality evidence). No studies reported maternal mortality or major neurodevelopmental disability at childhood follow-up. There were no clear group differences found in any of the other maternal or infant outcomes (preterm birth less than 37 weeks (average RR 0.97, 95% CI 0.89 to 1.06; women = 1597; studies = 6; moderate-quality evidence); preterm birth less than 28 weeks (RR 1.53, 95% CI 0.79 to 2.97; women = 1345; studies = 3; low-quality evidence); infant birthweight less than 2500 g (average RR 0.95, 95% CI 0.84 to 1.07; infants = 2640; studies = 3; I2 = 66%, moderate-quality evidence)). No childhood outcomes were reported in the trials. For secondary outcomes, there were no clear group differences found in any of the other maternal outcomes except for caesarean section, where women who received vaginal progesterone did not have as many caesarean sections as those in the placebo group, although the difference between groups was not large (8%) (RR 0.92, 95% CI 0.86 to 0.98; women = 1919; studies = 5; I2 = 0%). There were no clear group differences found in any of the infant outcomes except for mechanical ventilation, which was required by fewer infants whose mothers had received the vaginal progesterone (RR 0.70, 95% CI 0.52 to 0.94; infants = 2695; studies = 4).

AUTHORS' CONCLUSIONS

Overall, for women with a multiple pregnancy, the administration of progesterone (either IM or vaginal) does not appear to be associated with a reduction in risk of preterm birth or improved neonatal outcomes. Future research could focus on a comprehensive individual participant data meta-analysis including all of the available data relating to both IM and vaginal progesterone administration in women with a multiple pregnancy, before considering the need to conduct trials in subgroups of high-risk women (for example, women with a multiple pregnancy and a short cervical length identified on ultrasound).

Prevention and Therapy of Preterm Birth. Guideline of the DGGG, OEGGG and SGGG (S2k Level, AWMF Registry Number 015/025, February 2019) - Part 2 with Recommendations on the Tertiary Prevention of Preterm Birth and the Management of Preterm Premature Rupture of Membranes

Aims This is an official guideline of the German Society for Gynecology and Obstetrics (DGGG), the Austrian Society for Gynecology and Obstetrics (ÖGGG) and the Swiss Society for Gynecology and Obstetrics (SGGG). The aim of this guideline is to improve the prediction, prevention and management of preterm birth based on evidence obtained from recently published scientific literature, the experience of the members of the guideline commission and the views of self-help groups. Methods The members of the participating medical societies and organizations developed Recommendations and Statements based on the international literature. The Recommendations and Statements were adopted following a formal consensus process (structured consensus conference with neutral moderation, voting done in writing using the Delphi method to achieve consensus). Recommendations Part 2 of this short version of the guideline presents Statements and Recommendations on the tertiary prevention of preterm birth and the management of preterm premature rupture of membranes.

Progesterone for the Prevention of Preterm Birth - an Update of Evidence-Based Indications

The prevention and treatment of preterm birth remains one of the biggest challenges in obstetrics. Worldwide, 11% of all children are born prematurely with far-reaching consequences for the children concerned, their families and the health system. Experimental studies suggest that progesterone inhibits uterine contractions, stabilises the cervix and has immunomodulatory effects. Recent years have seen the publication of numerous clinical trials using progestogens for the prevention of preterm birth. As a result of different inclusion criteria and the use of different progestogens and their methods of administration, it is difficult to draw comparisons between these studies. A critical evaluation of the available studies was therefore carried out on the basis of a search of the literature (1956 to 09/2018). Taking into account the most recent randomised, controlled studies, the following evidence-based recommendations emerge: In asymptomatic women with singleton pregnancies and a short cervical length on ultrasound of ≤ 25 mm before 24 weeks of gestation (WG), daily administration of vaginal progesterone (200 mg capsule or 90 mg gel) up until 36 + 6 WG leads to a significant reduction in the preterm birth rate and an improvement in neonatal outcome. The latest data also suggest positive effects of treatment with progesterone in cases of twin pregnancies with a short cervical length on ultrasound of ≤ 25 mm before 24 WG. The study data for the administration of progesterone in women with singleton pregnancies with a previous preterm birth have become much more heterogeneous, however. It is not possible to make a general recommendation for this indication at present, and decisions must therefore be made on a case-by-case basis. Even if progesterone use is considered to be safe in terms of possible long-term consequences, exposure should be avoided where it is not indicated. Careful patient selection is crucial for the success of treatment.

Controversies about the Secondary Prevention of Spontaneous Preterm Birth

Preterm birth is one of the major global health problems and part of the Millennium Development goals because of the associated high number of perinatal or neonatal mortality and long-term risks of neurodevelopmental and metabolic diseases. Transvaginal sonography has meanwhile been established as a screening tool for spontaneous preterm birth despite its relatively low sensitivity when considering only the cervical length. Vaginal progesterone has been shown to reduce prematurity rates below 34 weeks in a screening population of singleton pregnancies. Up to now, no positive long-term effect could be demonstrated after 2 years. It seems to have no benefit to prolong pregnancies after a period of preterm contractions and in risk patients without cervical shortening. Meta-analyses still demonstrate conflicting results dependent on quality criteria used for selection. A cerclage is only indicated in singleton pregnancies with previous spontaneous preterm birth and a combined cervical shortening in the current pregnancy. Nevertheless, the short- and long-term outcome has never been evaluated, whereas maternal complications may be increased. There is no evidence for a prophylactic cervical cerclage in twin pregnancies even in cases with cervical shortening. Emergency cerclage remains an indication after individual counseling. The effect of a cervical pessary in singleton pregnancy seems to be more pronounced in studies where a few investigators with increasing experience have treated and followed the patients at risk for preterm birth. Mainly in twin pregnancies, pessary treatment seems to be promising compared to other treatment options of secondary prevention when the therapy is started at early stages of precocious cervical ripening. At present, several international trials with the goal to reduce global rates of prematurity are in progress which will hopefully allow to specify the indications and methods of intervention for certain subgroups. When trials are summarized, prospective meta-analyses carry a lower risk of bias than the meanwhile uncontrolled magnitude of retrospective meta-analyses with conflicting results.

The effect of prenatal vaginal progesterone on cervical length in nonselected twin pregnancies

PURPOSE

The aim of this study was to investigate the influence of vaginal progesterone on cervical length (CL) in asymptomatic nonselected twin gestations.

METHODS

This was a secondary analysis of a randomized, double-blind, placebo-controlled trial of twin pregnancies exposed to vaginal progesterone or placebo. The CL was examined at six different time periods: 18-21⁺⁶ weeks (T1), 21-23⁺⁶ weeks (T2), 24-26⁺⁶ weeks (T3), 27-29⁺⁶ weeks (T4), 30-32⁺⁶ weeks (T5) and 33-34⁺⁶ weeks (T6). The rate of cervical shortening per week and the percent cervical shortening were compared between the groups, with analyses of the entire cohort and of those who delivered spontaneously according to gestational age at birth.

RESULTS

The final analysis included 184 women in the progesterone group and 188 women in the placebo group. The baseline characteristics were similar in both groups. No differences in cervical shortening in terms of absolute value or percent shortening were observed between the groups at each time period or throughout gestation. Furthermore, no difference was found in cervical shortening for those who delivered spontaneously.

CONCLUSION

Cervical shortening in asymptomatic nonselected twin pregnancies occurred at a similar rate, regardless of vaginal progesterone treatment.

Prenatal administration of progestogens for preventing spontaneous preterm birth in women with a multiple pregnancy

BACKGROUND

Multiple pregnancy is a strong risk factor for preterm birth, and more than 50% of women with a twin pregnancy will give birth prior to 37 weeks' gestation. Infants born preterm are recognised to be at increased risk of many adverse health outcomes, contributing to more than half of overall perinatal mortality. Progesterone is produced naturally in the body and has a role in maintaining pregnancy, although it is not clear whether administering progestogens to women with multiple pregnancy at high risk of early birth is effective and safe.

OBJECTIVES

To assess the benefits and harms of progesterone administration for the prevention of preterm birth in women with a multiple pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (1 November 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials examining the administration of a progestogen by any route for the prevention of preterm birth in women with multiple pregnancy. We did not include quasi-randomised or cross-over studies.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed reports identified by the search for eligibility, extracted data, assessed risk of bias and graded the quality of the evidence.

MAIN RESULTS

We included 17 trials, which all compared either vaginal or intramuscular (IM) progesterone with a placebo or no treatment, and involved a total of 4773 women. The risk of bias for the majority of included studies was low, with the exception of four studies that had inadequate blinding, or significant loss to follow-up or both, or were not reported well enough for us to make a judgement. We graded the evidence low to high quality, with downgrading for statistical heterogeneity, design limitations in some of the studies contributing data, and imprecision of the effect estimate. 1 IM progesterone versus no treatment or placeboMore women delivered at less than 34 weeks' gestation in the IM progesterone group compared with placebo (risk ratio (RR) 1.54, 95% confidence interval (CI) 1.06 to 2.26; women = 399; studies = 2; low-quality evidence). Although the incidence of perinatal death in the progesterone group was higher, there was considerable uncertainty around the effect estimate and high heterogeneity between studies (average RR 1.45, 95% CI 0.60 to 3.51; infants = 3089; studies = 6; I2 = 71%; low-quality evidence). No studies reported maternal mortality or major neurodevelopmental disability at childhood follow-up.There were no clear group differences found in any of the other maternal or infant outcomes (preterm birth less than 37 weeks (RR 1.05, 95% CI 0.98 to 1.13; women = 2010; studies = 5; high-quality evidence); preterm birth less than 28 weeks (RR 1.08, 95% CI 0.75 to 1.55; women = 1920; studies = 5; moderate-quality evidence); infant birthweight less than 2500 g (RR 0.99, 95% CI 0.90 to 1.08; infants = 4071; studies = 5; I2 = 76%, moderate-quality evidence)). No childhood outcomes were reported in the trials. 2 Vaginal progesterone versus no treatment or placebo by doseThere were no clear group differences in incidence of preterm birth before 34 weeks (average RR 0.83, 95% CI 0.63 to 1.09; women = 1727; studies = 6; I2 = 46%; low-quality evidence). Although fewer births before 34 weeks appeared to occur in the progesterone group, the CIs crossed the line of no effect. Incidence of perinatal death was higher in the progesterone group, although there was considerable uncertainty in the effect estimate and the quality of the evidence was low for this outcome (RR 1.23, 95% CI 0.74 to 2.06; infants = 2287; studies = 3; low-quality evidence). No studies reported maternal mortality or major neurodevelopmental disability at childhood follow-up.There were no clear group differences found in any of the other maternal or infant outcomes (preterm birth less than 37 weeks (average RR 0.97, 95% CI 0.89 to 1.06; women = 1597; studies = 6; moderate-quality evidence); preterm birth less than 28 weeks (RR 1.22, 95% CI 0.68 to 2.21; women = 1569; studies = 4; low-quality evidence); infant birthweight less than 2500 g (RR 0.95, 95% CI 0.88 to 1.03; infants = 3079; studies = 4; I2 = 49%, moderate-quality evidence)). No childhood outcomes were reported in the trials.For secondary outcomes, there were no clear group differences found in any of the other maternal outcomes except for caesarean section, where women who received vaginal progesterone did not have as many caesarean sections as those in the placebo group, although the difference between groups was not large (7%) (RR 0.93, 95% CI 0.88 to 0.98; women = 2143; studies = 6; I2 = 0%). There were no clear group differences found in any of the infant outcomes except for mechanical ventilation, which was required by fewer infants whose mothers had received the vaginal progesterone (RR 0.61, 95% CI 0.48 to 0.77; infants = 3134; studies = 5).

AUTHORS' CONCLUSIONS

Overall, for women with a multiple pregnancy, the administration of progesterone (either IM or vaginal) does not appear to be associated with a reduction in risk of preterm birth or improved neonatal outcomes.Future research could focus on a comprehensive individual participant data meta-analysis including all of the available data relating to both IM and vaginal progesterone administration in women with a multiple pregnancy, before considering the need to conduct trials in subgroups of high-risk women (for example, women with a multiple pregnancy and a short cervical length identified on ultrasound).

Use of progesterone supplement therapy for prevention of preterm birth: review of literatures

Preterm birth (PTB) is one of the most common complications during pregnancy and it primarily accounts for neonatal mortality and numerous morbidities including long-term sequelae including cerebral palsy and developmental disability. The most effective treatment of PTB is prediction and prevention of its risks. Risk factors of PTB include history of PTB, short cervical length (CL), multiple pregnancies, ethnicity, smoking, uterine anomaly and history of curettage or cervical conization. Among these risk factors, history of PTB, and short CL are the most important predictive factors. Progesterone supplement therapy is one of the few proven effective methods to prevent PTB in women with history of spontaneous PTB and in women with short CL. There are 2 types of progesterone therapy currently used for prevention of PTB: weekly intramuscular injection of 17-alpha hydroxyprogesterone caproate and daily administration of natural micronized progesterone vaginal gel, vaginal suppository, or oral capsule. However, the efficacy of progesterone therapy to prevent PTB may vary depending on the administration route, form, dose of progesterone and indications for the treatment. This review aims to summarize the efficacy and safety of progesterone supplement therapy on prevention of PTB according to different indication, type, route, and dose of progesterone, based on the results of recent randomized trials and meta-analysis.

Vaginal progesterone decreases preterm birth and neonatal morbidity and mortality in women with a twin gestation and a short cervix: an updated meta-analysis of individual patient data

OBJECTIVE

To assess the efficacy of vaginal progesterone for the prevention of preterm birth and neonatal morbidity and mortality in asymptomatic women with a twin gestation and a sonographic short cervix (cervical length ≤ 25 mm) in the mid-trimester.

METHODS

This was an updated systematic review and meta-analysis of individual patient data (IPD) from randomized controlled trials comparing vaginal progesterone with placebo/no treatment in women with a twin gestation and a mid-trimester sonographic cervical length ≤ 25 mm. MEDLINE, EMBASE, POPLINE, CINAHL and LILACS (all from inception to 31 December 2016), the Cochrane Central Register of Controlled Trials, Research Registers of ongoing trials, Google Scholar, conference proceedings and reference lists of identified studies were searched. The primary outcome measure was preterm birth < 33 weeks' gestation. Two reviewers independently selected studies, assessed the risk of bias and extracted the data. Pooled relative risks (RRs) with 95% confidence intervals (CI) were calculated.

RESULTS

IPD were available for 303 women (159 assigned to vaginal progesterone and 144 assigned to placebo/no treatment) and their 606 fetuses/infants from six randomized controlled trials. One study, which included women with a cervical length between 20 and 25 mm, provided 74% of the total sample size of the IPD meta-analysis. Vaginal progesterone, compared with placebo/no treatment, was associated with a statistically significant reduction in the risk of preterm birth < 33 weeks' gestation (31.4% vs 43.1%; RR, 0.69 (95% CI, 0.51-0.93); moderate-quality evidence). Moreover, vaginal progesterone administration was associated with a significant decrease in the risk of preterm birth < 35, < 34, < 32 and < 30 weeks' gestation (RRs ranging from 0.47 to 0.83), neonatal death (RR, 0.53 (95% CI, 0.35-0.81)), respiratory distress syndrome (RR, 0.70 (95% CI, 0.56-0.89)), composite neonatal morbidity and mortality (RR, 0.61 (95% CI, 0.34-0.98)), use of mechanical ventilation (RR, 0.54 (95% CI, 0.36-0.81)) and birth weight < 1500 g (RR, 0.53 (95% CI, 0.35-0.80)) (all moderate-quality evidence). There were no significant differences in neurodevelopmental outcomes at 4-5 years of age between the vaginal progesterone and placebo groups.

CONCLUSION

Administration of vaginal progesterone to asymptomatic women with a twin gestation and a sonographic short cervix in the mid-trimester reduces the risk of preterm birth occurring at < 30 to < 35 gestational weeks, neonatal mortality and some measures of neonatal morbidity, without any demonstrable deleterious effects on childhood neurodevelopment. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

The safety of progestogen in the prevention of preterm birth: meta-analysis of neonatal mortality

BACKGROUND

The safety of preventive progestogen therapy for preterm birth remains to be established. This meta-analysis aimed to evaluate the effects of preventive progestogen therapy on neonatal mortality.

METHODS

Randomized controlled trials (RCTs) on the preventive use of progestogen therapy, published between October 1971 and November 2015, were identified by searching MEDLINE/PubMed, EMBASE, Scopus, ClinicalTrials.gov, Cochrane Library databases, CINAHL, POPLINE, and LILACS using "progesterone" and "preterm birth" as key terms. We conducted separate analyses according to the type of progestogen administered and plurality of the pregnancy.

RESULTS

Twenty-two RCTs provided data on 11,188 neonates. Preventive progestogen treatment in women with a history of preterm birth or short cervical length was not associated with increased risk of neonatal death compared to placebo in all analyzed progestogen types and pregnancy conditions. The pooled relative risks (95% confidence interval) of neonatal mortality were 0.69 (0.31-1.54) for vaginal progestogen in singleton pregnancies, 0.6 (0.33-1.09) for intramuscular progestogen in singleton pregnancies, 0.96 (0.51-1.8) for vaginal progestogen in multiple pregnancies, and 0.96 (0.49-1.9) for intramuscular progestogen in multiple pregnancies.

CONCLUSIONS

The results of this meta-analysis suggest that administration of preventive progestogen treatment to women at risk for preterm birth does not appear to negatively affect neonatal mortality in single or multiple pregnancies regardless of the route of administration.

Do serial measurements of cervical length improve the prediction of preterm birth in asymptomatic women with twin gestations?

BACKGROUND

Cervical length at midtrimester is a powerful predictor of preterm birth in twin gestations. However, given the fact that, in some cases, cervical shortening may become evident only later during the second trimester, it seems reasonable that serial monitoring of cervical length may improve the detection of preterm birth in women with twins. However, data in support of such a practice are limited and conflicting. The contradictory results may be related to the fact that in most of these studies, the analysis of the predictive value of serial measurements of cervical length was limited to data derived from only two sequential measurements of cervical length, while data on the predictive value of multiple (>2) measurements are scarce.

OBJECTIVE

We sought to determine whether serial measurements of cervical length can improve the prediction of preterm birth in asymptomatic women with twin gestations compared with a single measurement of cervical length at midgestation.

STUDY DESIGN

This was a retrospective cohort study of women with twin pregnancies followed up in a tertiary medical center from 2012 through 2014. All participants underwent routine measurement of cervical length at midgestation and every 2-3 weeks thereafter until 28-32 weeks. For each patient, cervical length was determined at the following time periods: 18+0 to 21+6 weeks (period 1, routine exam), 22+0 to 24+6 weeks (period 2), 25+0 to 27+6 weeks (period 3), and 28+0 to 32+0 weeks (period 4). Measurements of cervical length at periods 2-4 were analyzed in the form of either absolute length (in millimeters) or percent shortening relative to cervical length at period 1. The performance of a stepwise algorithm that incorporated serial measurements of cervical length for the prediction of preterm birth was compared to that achieved with a single measurement of cervical length at period 1.

RESULTS

Overall, 441 women with twin pregnancies who were eligible for the study underwent a total of 2374 cervical length measurements. The association of a short cervix (<10th percentile) with preterm birth at <32 weeks persisted in each of the 4 periods of gestation [odds ratio (95% confidence interval): 7.2 (3.1-16.5), 15.3 (6.4-36.7), 10.3 (4.4-24.3), and 23.1(8.3-64.1), respectively]. Compared with a single measurement of cervical length at midgestation (period 1), a stepwise algorithm integrating serial cervical length measurements from all 4 successive gestational age periods resulted in a significant increase in the area under the receiver operating characteristic curve (0.917 vs 0.613, P < .001). Similarly, when a target false-positive rate of 5% was used, the same stepwise algorithm was associated with a higher detection rate (69% vs 28%, P < .001), higher positive likelihood ratio (14.54 vs 5.12), and lower negative likelihood ratio (0.32 vs 0.76) for preterm birth at <32 weeks compared with a single measurement of cervical length at period 1.

CONCLUSION

Integration of serial measurements of cervical length using a stepwise algorithm in asymptomatic women with twin gestations can improve the detection of women at risk of preterm birth. Prospective studies are needed to validate these findings, and to investigate whether improved risk assessment performance is sufficient to offset the additional costs associated with serial cervical length measurements.

The effect of prenatally administered vaginal progesterone on uterine artery Doppler in asymptomatic twin pregnancies

OBJECTIVES

This study investigated the influence of vaginal progesterone on uterine circulation in asymptomatic twin gestations.

STUDY DESIGN

This study was a secondary analysis of a randomized, double-blind, placebo-controlled trial of twin pregnancies exposed to vaginal progesterone or placebo. We included all trial participants who had undergone uterine artery pulsatility index evaluation at the time of randomization. During each ultrasound examination, the uterine artery pulsatility index was evaluated transabdominally. The mean uterine artery pulsatility index between the progesterone and placebo groups were compared for each gestational age, starting between 18 to 34 weeks and 6days and were analyzed at three (Time 1), six (Time 2) and nine (Time 3) weeks after randomization.

RESULTS

The final analysis included 128 women in the progesterone group and 122 women in the placebo group. The baseline characteristics were similar in both groups. No difference in the mean uterine artery pulsatility index was observed between the progesterone and placebo groups at each week of gestation or throughout gestation.

CONCLUSIONS

In twin pregnancies, the use of vaginal progesterone in the second half of pregnancy does not influence uterine circulation.

Prenatal administration of vaginal progesterone and frequency of uterine contractions in asymptomatic twin pregnancies

INTRODUCTION

A previous study indicated that progesterone reduces the mean uterine contraction frequency in singleton pregnancy at high risk for preterm birth. The aim of this study was to investigate the effect of vaginal progesterone on the frequency of uterine contractions in twin pregnancies.

MATERIAL AND METHODS

This was a secondary analysis of a randomized, double-blind, placebo-controlled trial of twin pregnancies exposed to vaginal progesterone or placebo. Naturally conceived twin pregnancies with no prior history of preterm delivery, asymptomatic regarding preterm labor, who had undergone uterine contraction frequency monitoring from 24 to 34 weeks and 6 days were included in the study. Comparison of the mean frequency of uterine contractions between the treatment groups was performed. We also examined the influence of cervical length and chorionicity on the mean frequency of uterine contractions according to the group.

RESULTS

The final analysis included 166 women in the progesterone and 170 in the placebo group. The baseline characteristics were similar in the two groups. Overall, no difference in the mean frequency of uterine contractions (p = 0.91) was observed between the progesterone (2.54 ± 3.19) and placebo (2.56 ± 3.59) groups. Also, no difference in the mean frequency of uterine contractions was observed between the groups in each week between 24 and 34 weeks and 6 days of gestation. Cervical length and chorionicity did not influence the frequency of contractions according to the progesterone or placebo treatment.

CONCLUSIONS

Overall, progesterone does not influence the frequency of uterine contractions in twin pregnancies.

Prevention of preterm birth with vaginal progesterone or 17-alpha-hydroxyprogesterone caproate: a critical examination of efficacy and safety

Progestogens are the first drugs to demonstrate reproducibly a reduction in the rate of early preterm birth. The efficacy and safety of progestogens are related to individual pharmacologic properties of each drug within this class of medication and characteristics of the population that is treated. The synthetic 17-hydroxyprogesterone caproate and natural progesterone have been studied with the use of a prophylactic strategy in women with a history of preterm birth and in women with a multiple gestation. Evidence from a single large comparative efficacy trial suggests that vaginal natural progesterone is superior to 17-hydroxyprogesterone caproate as a prophylactic treatment in women with a history of mid-trimester preterm birth. Progestogen therapy is indicated for women with this highest risk profile based on evidence from 2 trials. A therapeutic approach based on the identification of a sonographic short cervix has been studied in several phase III trials. Independent phase III trials and an individual patient metaanalysis suggest that vaginal progesterone is efficacious and safe in women with a singleton and a short cervix. Two trials that tested 17-hydroxyprogesterone caproate in women with a short cervix showed no benefit. No consistent benefit for the prophylactic or therapeutic use of progestogens has been demonstrated in larger trials of women whose pregnancies were complicated by a multiple gestation (twins or triplets), preterm labor, or preterm rupture of membranes. Unfortunately, several large randomized trials in multiple gestations have identified harm related to 17-hydroxyprogesterone caproate exposure, and the synthetic drug is contraindicated in this population. The current body of evidence is evaluated by the Grading of Recommendations Assessment, Development, and Evaluation guidelines to derive the strength of recommendation in each of these populations. A large confirmatory trial that is testing 17-hydroxyprogesterone caproate exposure in women with a singleton pregnancy and a history of preterm birth is near completion. Additional study of the efficacy and safety of progestogens is suggested in well-selected populations based on the presence of biomarkers.

17-Hydroxyprogesterone caproate in triplet pregnancy: an individual patient data meta-analysis

BACKGROUND

Preterm birth complicates almost all triplet pregnancies and no preventive strategy has proven effective.

OBJECTIVE

To determine, using individual patient data (IPD) meta-analysis, whether the outcome of triplet pregnancy is affected by prophylactic administration of 17-hydroxyprogesterone caproate (17OHPc).

SEARCH STRATEGY

We searched literature databases, trial registries and references in published articles.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of progestogens versus control that included women with triplet pregnancies.

DATA COLLECTION AND ANALYSIS

Investigators from identified RCTs collaborated on the protocol and contributed their IPD. The primary outcome was a composite measure of adverse perinatal outcome. The secondary outcome was the rate of birth before 32 weeks of gestation. Other pre-specified outcomes included randomisation-to-delivery interval and rates of birth at <24, <28 and <34 weeks of gestation.

MAIN RESULTS

Three RCTs of 17OHPc versus placebo included 232 mothers with triplet pregnancies and their 696 offspring. Risk-of-bias scores and between-study heterogeneity were low. Baseline characteristics were comparable between 17OHPc and placebo groups. The rate of the composite adverse perinatal outcome was similar among those treated with 17OHPc and those treated with placebo (34 and 35%, respectively; risk ratio [RR] 0.98, 95% confidence interval [95% CI] 0.79-1.2). The rate of birth at <32 weeks was also similar in the two groups (35 and 38%, respectively; RR 0.92, 95% CI 0.55-1.56). There were no significant between-group differences in perinatal mortality rate, randomisation-to-delivery interval, or other specified outcomes.

CONCLUSION

Prophylactic 17OHPc given to mothers with triplet pregnancies had no significant impact on perinatal outcome or pregnancy duration.

TWEETABLE ABSTRACT

17-Hydroxyprogesterone caproate had no significant impact on the outcome or duration of triplet pregnancy.

The effect of gestational age and cervical length measurements in the prediction of spontaneous preterm birth in twin pregnancies: an individual patient level meta-analysis

OBJECTIVE

To assess the effect of gestational age (GA) and cervical length (CL) measurements at transvaginal ultrasound (TVUS) in the prediction of preterm birth in twin pregnancy.

DESIGN

Individual patient data (IPD) meta-analysis.

SETTING

International multicentre study.

POPULATION

Asymptomatic twin pregnancy.

METHODS

MEDLINE and EMBASE searches were performed and IPD obtained from authors of relevant studies. Multinomial logistic regression analysis determined probabilities for birth at ≤28(+0) , 28(+1) to 32(+0) , 32(+1) to 36(+0) , and ≥36(+1) weeks as a function of GA at screening and CL measurements.

MAIN OUTCOME MEASURES

Predicted probabilities for preterm birth at ≤28(+0) , 28(+1) to 32(+0) , and 32(+1) to 36(+0) .

RESULTS

A total of 6188 CL measurements were performed on 4409 twin pregnancies in 12 studies. Both GA at screening and CL had a significant and non-linear effect on GA at birth. The best prediction of birth at ≤28(+0) weeks was provided by screening at ≤18(+0) weeks (P < 0.001), whereas the best prediction of birth between 28(+1) and 36(+0) weeks was provided by screening at ≥24(+0) weeks (P < 0.001). Negative prediction value of 100% for birth at ≤28(+0) weeks is achieved at CL 65 mm and 43 mm at ultrasound GA at ≤18(+0) weeks and at 22(+1) to 24(+0) weeks, respectively.

CONCLUSION

In twin pregnancies, prediction of preterm birth depends on both CL and the GA at screening. When CL is <30 mm, screening at ≤18(+0) weeks is most predictive for birth at ≤28(+0) weeks. Later screening at >22(+0) weeks is most predictive of delivery at 28(+1) to 36(+0) weeks. In twins, we recommend CL screening in twins to commence from ≤18(+0) weeks.

TWEETABLE ABSTRACT

An individual patient meta-analysis assessing gestation and CL in the prediction of preterm birth in twins.