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

General Principles for Counseling and Management of Triplet Pregnancies

Compared with singleton pregnancies, triplet pregnancies are associated with a significantly increased risk of adverse pregnancy outcomes. Early ultrasound examination is the best way to diagnose triplets, establish dating, and determine the number of placentas to provide appropriate counseling and monitoring. Dichorionic placentation adds risks specifically associated with a shared placenta, and limits options for intervention. Multifetal reduction is an option that can significantly improve pregnancy outcomes compared with non-reduced triplet pregnancies. Integration of a Maternal-Fetal Medicine specialist in the prenatal care for a triplet pregnancy reduces the risk of preeclampsia, preterm birth, low birthweight infants, perinatal mortality, and major neonatal morbidity.

Delivery prediction by quantitative analysis of four steroid metabolites with liquid chromatography tandem mass spectrometry in asymptomatic pregnant women

BACKGROUND

Prediction of delivery is important for assessing due dates, providing adequate prenatal care, and suggesting appropriate interventions in preterm and post-term pregnancies. Recent metabolomic findings suggested that the temporal abundance information of metabolome can be used to predict delivery timing with high accuracy in a cohort of healthy women. However, a targeted and quantitative assay is required to further validate the clinical performance and utility of this group of metabolomic candidates in delivery prediction with a larger and independent cohort.

METHOD

LC-MS/MS quantitative assays were applied to determine the plasma concentrations of four steroid metabolites, including oestriol-16-glucuronide (E3-16-Gluc), 17-alpha-hydroxyprogesterone (17-OHP), tetrahydrodeoxycorticosterone (THDOC), and androstane-3,17-diol (A-3,17-Diol) in asymptomatic women of singleton pregnancies (≥30^th gestational weeks). Subsequent statistical analysis was conducted to assess the performance of the above candidates in delivery prediction.

RESULT

Using LC-MS/MS, four steroids were separated and quantified in 5.5 min. The coefficients of variation (CVs) of the four analytes at the lower limit of quantification ranged from 7.9% to 14.6%, with the R² values greater than 0.990 in the calibration curves. Of the 585 recruited pregnant women who ended up with spontaneous delivery, 17.1% and 82.9% of the subjects delivered within and after 7 days since plasma collection, respectively. In the receiver operator curve analysis, the gestational age-adjusted area under the curve of the combined measurements of E3-16-Gluc and 17-OHP was 0.69 (95% CI: 0.60-0.76), with the sensitivity of 87.0% (95% CI: 78.8%-92.9%) and specificity of 60.2% (95% CI: 55.7%-64.6%). Moreover, the positive and the negative predictive values were 28.3%-34.0% and 93.1%-97.4% respectively for this combined panel.

CONCLUSION

We performed analytical and clinical validation of a quantitation LC-MS/MS panel for the four steroids in the plasma of pregnant women. The steroid metabolites panel of E3-16-Gluc and 17-OHP was potentially useful for predicting delivery within one week in asymptomatic women of singleton pregnancies. Key messagesA quantitative LC-MS/MS assay for determining the plasma levels of 17-OHP, THDOC, A-3,17-Diol and E3-16-Gluc was developed and validated, in order to evaluate their predictive performance in asymptomatic delivery of singleton pregnancy. The levels of E3-16-Gluc and 17-OHP were found to be significantly elevated at the time of sampling in women that delivered within one week and their combinational testing may be potentially useful in delivery prediction.

Gestational age-based reference ranges for cervical length and preterm birth prediction in triplet pregnancies: an observational retrospective study

OBJECTIVES

To develop gestational age-based reference ranges for cervical length in triplet pregnancies. The secondary objective was to assess the performance of cervical length measured between 18 and 20 + 6 days for the prediction of preterm delivery before 28 and 32 weeks, respectively.

METHODS

Observational retrospective study of triplet pregnancies in three Spanish tertiary-care hospitals between 2001 and 2019. Cervical length measurements were consecutively obtained between 15 and 34 weeks of gestation. Pregnancies undergoing multifetal reduction or fetal surgery were excluded.

RESULTS

Two hundred and six triplet pregnancies were included in the final analysis. There was a quadratic decrease in cervical length with gestational age. The median and fifth centiles for cervical length at 20 weeks were 35 and 13 mm. In the prediction of preterm birth < 28 weeks, for a false positive rate of 5%, and 10%, the detection rates were 40.9%, and 40.9%, respectively, and the prediction of preterm birth < 32 weeks, 22.0% and 26.0%, respectively.

CONCLUSIONS

In triplet pregnancies, cervical length decreases with gestational age. The performance of cervical length at 18-20 + 6 in screening for preterm birth before 28 and 32 weeks is poor.

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.

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.

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

BACKGROUND

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

OBJECTIVE

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

DATA SOURCES

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

STUDY ELIGIBILITY CRITERIA

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

STUDY APPRAISAL AND SYNTHESIS METHODS

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

RESULTS

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

CONCLUSION

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

Recurrence risk of preterm birth in a subsequent singleton pregnancy after a spontaneous preterm triplet delivery

OBJECTIVE

History of prior preterm birth (PTB) represents one of the strongest risk factors for recurrent PTB. Nevertheless, whether the occurrence of PTB in multifetal gestation is associated with increased risk of PTB in subsequent pregnancies remains unclear. We aimed to determine the recurrence risk of PTB in a subsequent singleton pregnancy after a previous spontaneous preterm triplet delivery.

STUDY DESIGN

A retrospective matched case-control study. The study group comprised all women with spontaneous preterm trichorionic triplet delivery who had a subsequent singleton pregnancy during 2006-2017 at two university hospitals. A control group of women with spontaneous preterm dichorionic twin delivery and a subsequent singleton pregnancy, was established by matching, four-to-one, according to maternal age, parity, gestational age at delivery, and delivery year.

RESULTS

Data from 170 women were analyzed, 34 with preterm triplet delivery and 136 matched control women with preterm twin delivery. Gestational age at the subsequent singleton delivery was higher in those with preterm triplet delivery than in those with preterm twin delivery (median 39 vs 38 weeks, P = 0.02). Women with prior triplet PTB had a significantly lower rate of recurrent PTB as compared with women with prior twin PTB (5.9 % vs. 25.0 %; OR [95 % CI]: 0.19 (0.04, 0.82), P = 0.02) with lower proportions of low-birth weight infants (<2500 g) (0 % vs. 11.8 %, P = 0.04).

CONCLUSIONS

The risk of recurrent PTB following spontaneous PTB in triplet pregnancy was low compared to preterm twin delivery. These data provide reassurance for those who experienced preterm triplet delivery and suggest the need for further studies to understand the mechanisms contributing to PTB in multifetal pregnancies.

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).

Cervical-length measurement in mid-gestation to predict spontaneous preterm birth in asymptomatic triplet pregnancy

OBJECTIVE

To assess the predictive value of sonographic cervical-length (CL) measurement in mid-gestation for spontaneous preterm birth (PTB) in asymptomatic triplet pregnancy.

METHODS

This was a retrospective study of asymptomatic triplet pregnancies followed at five Italian tertiary referral centers, between 2002 and 2015. CL was measured transvaginally between 18 and 24 weeks' gestation. Pregnancies with medically indicated PTB were excluded. Demographic and pregnancy characteristics of pregnancies complicated by PTB were analyzed and the distributions of CL measurements in these patients were calculated. Logistic regression analysis was performed to assess the association between CL and PTB, adjusted for confounders. Performance of CL measurement in prediction of PTB < 28, < 30 and < 32 weeks of gestation was assessed.

RESULTS

A total of 120 triplet pregnancies were included in the final analysis. Median CL was 35 (interquartile range (IQR), 29-40) mm measured at a median gestational age of 20 + 2 (IQR, 20 + 0 to 23 + 4) weeks. Overall, 23 (19.2%), 17 (14.2%) and eight (6.7%) patients had a CL < 25, < 20 and < 15 mm, respectively. Spontaneous PTB < 32 weeks occurred in 41 (34.2%) cases, < 30 weeks in 23 (19.2%) and < 28 weeks in 12 (10%) cases. CL < 15 mm was significantly more frequent in the group of patients who delivered < 28 (P = 0.03) and < 30 (P = 0.01) weeks' gestation, compared with those who delivered after 28 and after 30 weeks, respectively, while CL < 20 mm was more common in triplet pregnancies with delivery < 32 weeks compared with those delivered ≥ 32 weeks (P = 0.03). Logistic regression analysis was possible only for PTB < 32 weeks due to the small number of cases that delivered < 30 and < 28 weeks. After adjustment for confounders, CL was not significantly associated with PTB < 32 weeks (adjusted odds ratio, 0.97; 95% CI, 0.94-1.01). CL measurement had an area under the receiver-operating characteristics curve of 0.41 (95% CI, 0.20-0.62), 0.41 (95% CI, 0.26-0.56) and 0.42 (95% CI, 0.31-0.54) for the prediction of spontaneous PTB < 28, < 30 and < 32 weeks, respectively.

CONCLUSION

CL assessed in mid-gestation is a poor predictor of PTB < 28, < 30 and < 32 weeks' gestation in asymptomatic triplet pregnancy. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Evaluating progestogens for prevention of preterm birth international collaborative (EPPPIC) individual participant data (IPD) meta-analysis: protocol

BACKGROUND

Preterm birth is the most common cause of death and harm to newborn babies. Babies that are born early may have difficulties at birth and experience health problems during early childhood. Despite extensive study, there is still uncertainty about the effectiveness of progestogen (medications that are similar to the natural hormone progesterone) in preventing or delaying preterm birth, and in improving birth outcomes. The Evaluating Progestogen for Prevention of Preterm birth International Collaborative (EPPPIC) project aims to reduce uncertainty about the specific conditions in which progestogen may (or may not) be effective in preventing or delaying preterm birth and improving birth outcomes.

METHODS

The design of the study involves international collaborative individual participant data meta-analysis comprising systematic review, re-analysis, and synthesis of trial datasets. Inclusion criteria are as follows: randomized controlled trials comparing progestogen versus placebo or non-intervention, or comparing different types of progestogen, in asymptomatic women at risk of preterm birth. Main outcomes are as follows; fetal/infant death, preterm birth or fetal death (<=37 weeks, <=34 weeks, <= 28 weeks), serious neonatal complications or fetal/infant death, neurosensory disability (measured at 18 months or later) or infant/child death, important maternal morbidity, or maternal death. In statistical methods, IPD will be synthesized across trials using meta-analysis. Both 'two-stage' models (where effect estimates are calculated for each trial and subsequently pooled in a meta-analysis) and 'one-stage' models (where all IPD from all trials are analyzed in one step, while accounting for the clustering of participants within trials) will be used. If sufficient suitable data are available, a network meta-analysis will compare all types of progesterone and routes of administration extending the one-stage models to include multiple treatment arms.

DISCUSSION

EPPPIC is an international collaborative project being conducted by the forming EPPPIC group, which includes trial investigators, an international secretariat, and the research project team. Results, which are intended to contribute to improvements in maternal and child health, are expected to be publicly available in mid 2018.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017068299.

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).

Real-time continuous glucose monitoring in type 1 diabetes: a systematic review and individual patient data meta-analysis

BACKGROUND

Real-time continuous glucose monitoring (RTCGM) may help in the management of individuals with type 1 diabetes mellitus (T1DM); however, the evidence supporting its use is unclear. The available meta-analyses on this topic use aggregate data which weaken inference.

OBJECTIVE

Individual patient data were obtained from randomized controlled trials (RCTs) to conduct a meta-analysis and synthesize evidence about the effect of RTCGM on glycosylated haemoglobin (HbA1c), hypoglycaemic events and time spent in hypoglycaemia in T1DM.

METHODS

We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and Database of Systematic Reviews, and Scopus through January 2015. We included RCTs that enrolled individuals with T1DM and compared RTCGM vs control group. A two-step regression model was used to pool individual patient data.

RESULTS

We included 11 RCTs at moderate risk of bias. Meta-analysis suggests that the use of RTCGM is associated with a statistically significant but modest reduction in HbA1c (-0·276; 95% confidence interval -0·465 to -0·087). The improvements in HbA1c were primarily seen in individuals over age 15 years. We were unable to identify a statistically significant difference in time spent in hypoglycaemia or the number of hypoglycaemic episodes although these analyses were imprecise and warrant lower confidence. There was no difference between males and females.

CONCLUSION

RTCGM in T1DM is associated with a reduction in HbA1c primarily in individuals over 15 years of age. We were unable to identify a statistically significant difference in the time spent in hypoglycaemia or the incidence of hypoglycaemic episodes.