Tocolytics for preterm premature rupture of membranes

Interventions for the prevention of spontaneous preterm birth: a scoping review of systematic reviews

BACKGROUND

Globally, 11% of babies are born preterm each year. Preterm birth (PTB) is a leading cause of neonatal death and under-five mortality and morbidity, with lifelong sequelae in those who survive. PTB disproportionately impacts low/middle-income countries (LMICs) where the burden is highest.

OBJECTIVES

This scoping review sought to the evidence for interventions that reduce the risk of PTB, focusing on the evidence from LMICs and describing how context is considered in evidence synthesis.

DESIGN

We conducted a scoping review, to describe this wide topic area. We searched five electronic databases (2009-2020) and contacted experts to identify relevant systematic reviews of interventions to reduce the risk of PTB. We included published systematic reviews that examined the effectiveness of interventions and their effect on reducing the risk of PTB. Data were extracted and is described narratively.

RESULTS

139 published systematic reviews were included in the review. Interventions were categorised as primary or secondary. The interventions where the results showed a greater effect size and consistency across review findings included treatment of syphilis and vaginal candidiasis, vitamin D supplementation and cervical cerclage. Included in the 139 reviews were 1372 unique primary source studies. 28% primary studies were undertaken in LMIC contexts and only 4.5% undertaken in a low-income country (LIC) Only 10.8% of the reviews sought to explore the impact of context on findings, and 19.4% reviews did not report the settings or the primary studies.

CONCLUSION

This scoping review highlights the lack of research evidence derived from contexts where the burden of PTB globally is greatest. The lack of rigour in addressing contextual applicability within systematic review methods is also highlighted. This presents a risk of inappropriate and unsafe recommendations for practice within these contexts. It also highlights a need for primary research, developing and testing interventions in LIC settings.

Expectant Management of PPROM Improves Neonatal Outcome-A Retrospective Study of 562 Patients

Prelabor preterm rupture of the membranes (PPROM) refers to the rupture of the membranes before 37 weeks, but also before the onset of labor. Approximately 3% of pregnancies are complicated by PPROM, which is an important cause of neonatal morbidity and mortality. The aim of the study is to demonstrate the benefit of expectant management in PPROM, compared to immediate birth, defined in our study as birth in the first 48 h. We analyzed 562 pregnancies with PPROM by gestational age groups and short-term morbidities. Material and methods: We conducted a retrospective observational analytical study, which included women with PPROM between 24 + 0 and 36 + 6 weeks. We divided the cohort into gestational age groups: group 1 gestational age (GA) between 24 and 27, group 2 GA between 28 and 31, group 3 GA between 32 and 34, group 4 GA > 35 weeks. In each group, we analyzed the benefit of the latency period (established in our study as delivery after 48 h of hospitalization) in terms of short-term neonatal complications. Result: The latency period brought a significant benefit starting with GA greater than 28 weeks; therefore, in the group with GA between 28–31, the complications were significantly statistically lower, mentioning respiratory distress syndrome (no latency 100% vs. latency 85.1%) and admission to the neonatal intensive care unit (no latency 89.7% vs. latency 70.2%). In group 3, with GA between 32–34, we reached statistical significance in terms of respiratory distress syndrome (no latency 61.8% vs. latency 39%), hypoxia (no latency 50% vs. latency 31.7%) and admission to the neonatal intensive care unit (no latency 70.2% vs. latency 47.4%). Conclusion: Expectant management of pregnancies with PPROM can bring a real benefit in terms of the incidence of complications in premature infants, but this benefit depends most on the gestational age at which the membranes ruptured and the medical conduct put into practice during the latency period.

Empirical comparison of univariate and multivariate meta-analyses in Cochrane Pregnancy and Childbirth reviews with multiple binary outcomes

BACKGROUND

Multivariate meta-analysis (MVMA) jointly synthesizes effects for multiple correlated outcomes. The MVMA model is potentially more difficult and time-consuming to apply than univariate models, so if its use makes little difference to parameter estimates, it could be argued that it is redundant.

METHODS

We assessed the applicability and impact of MVMA in Cochrane Pregnancy and Childbirth (CPCB) systematic reviews. We applied MVMA to CPCB reviews published between 2011 and 2013 with two or more binary outcomes with at least three studies and compared findings with results of univariate meta-analyses. Univariate random effects meta-analysis models were fitted using restricted maximum likelihood estimation (REML).

RESULTS

Eighty CPCB reviews were published. MVMA could not be applied in 70 of these reviews. MVMA was not feasible in three of the remaining 10 reviews because the appropriate models failed to converge. Estimates from MVMA agreed with those of univariate analyses in most of the other seven reviews. Statistical significance changed in two reviews: In one, this was due to a very small change in P value; in the other, the MVMA result for one outcome suggested that previous univariate results may be vulnerable to small-study effects and that the certainty of clinical conclusions needs consideration.

CONCLUSIONS

MVMA methods can be applied only in a minority of reviews of interventions in pregnancy and childbirth and can be difficult to apply because of missing correlations or lack of convergence. Nevertheless, clinical and/or statistical conclusions from MVMA may occasionally differ from those from univariate analyses.

Determinants of premature rupture of membrane in Southern Ethiopia, 2017: case control study design

OBJECTIVE

To identify the determinants of term premature rupture of membrane in Southern Ethiopia public hospitals, 2017.

RESULTS

Seventy-five cases and 223 controls women were enrolled for the study. Two hundred eighty-four (95.3%) participants were admitted at the gestational age of above 40, and the rest, 14 (4.7%), were admitted at 37-40 weeks of gestation. The current study identified wealth index and inter-birth interval as preventive predictors, but smoking and hypertension during pregnancy were identified as positive determinants of premature rupture of membrane. This finding is supported by multiple logistic regression analysis result of wealth index (AOR: 0.102, 95% CI [0.033, 0.315]), inter-birth interval (AOR: 0.251, 95% CI [0.129, 0 0.488]), smoking (AOR: 17.053, 95% CI [2.145, 135.6]), and hypertension (AOR: 8.92, 95% CI (1.91, 41.605]). The association between PROM and its determinants indicated that evidence-based interventions should be needed and designed to have very high wealth index, and optimal interbirth interval, and prevent smoking and hypertension during pregnancy to decrease PROM occurrence in the study settings. Hence, we recommended that integration of prevention mechanism of modifiable determinants to the obstetrics health care system will reduce premature ruptures of a membrane.

Perinatal outcomes after previable preterm premature rupture of membranes before 24 weeks of gestation

OBJECTIVE

A current descriptive assessment of perinatal outcomes in pregnancies complicated by previable preterm premature rupture of membranes (pPPROM) at <24 weeks of gestation, after expectant treatment.

STUDY DESIGN

Maternal and short-term neonatal data were collected for patients with pPPROM.

RESULTS

Seventy-three patients with 93 fetuses were hospitalized with pPPROM at 15-24 weeks' gestation. Among these patients, 27.4% (n=20) chose pregnancy termination, 27.4% (n=20) miscarried and 45.2% (n=33) proceeded to live births. After a median latency period of 38 days, ranging from 1 to 126 days, 24 singletons and 20 multiples were live-born, of whom 79.5% (n=35) survived the perinatal period. The main neonatal sequelae were pulmonary hypoplasia (29.5%; n=13), connatal infection (56.8%; n=25), intraventricular hemorrhage (25%; n=11; resulting in five neonatal deaths) and Potter's syndrome (15.9%; n=7). Nine newborns died, within an average of 2.8 days (range, 1-10 days). The overall neonatal survival rate was 51.5% - including miscarriages but not elective terminations. The intact survival rate was 45.5% of all live-born neonates.

CONCLUSIONS

Even with limited treatment options, overall neonatal survival is increasing. However, neonatal mortality and morbidity rates remain high. The gestational age at membrane rupture does not predict neonatal outcome.

Practice Bulletin No. 172: Premature Rupture of Membranes

Preterm delivery occurs in approximately 12% of all births in the United States and is a major factor that contributes to perinatal morbidity and mortality (1, 2). Preterm premature rupture of membranes (PROM) complicates approximately 3% of all pregnancies in the United States (3). The optimal approach to clinical assessment and treatment of women with term and preterm PROM remains controversial. Management hinges on knowledge of gestational age and evaluation of the relative risks of delivery versus the risks of expectant management (eg, infection, abruptio placentae, and umbilical cord accident). The purpose of this document is to review the current understanding of this condition and to provide management guidelines that have been validated by appropriately conducted outcome-based research when available. Additional guidelines on the basis of consensus and expert opinion also are presented.

Medical and Surgical Interventions Available Before a Periviable Birth

Periviable birth contributes disproportionately to perinatal morbidity and mortality. By analyzing the most relevant outcomes after a preterm birth some information can be provided on the potential benefit of interventions. This article discusses surgical and medical interventions that may offer neonatal benefit including cerclage, amniocentesis, progesterone, antenatal corticosteroids, magnesium sulfate for neuroprotection, and tocolysis. Cervical cerclage has the greatest promise at reducing morbidity and mortality related to periviable birth even though it may not reduce the overall preterm birth rate. The use of antenatal corticosteroids, magnesium sulfate, progesterone, and tocolytics may also improve outcome. Studies specifically evaluating these interventions are needed.

Evaluation of perinatal outcomes in pregnant women with preterm premature rupture of membranes

OBJECTIVE

To determine the association between amniotic fluid index (AFI) and perinatal outcomes in preterm premature rupture of membranes (PPROM).

METHOD

A retrospective cohort study was conducted between 2008 and 2012. 86 pregnant women were included, with a diagnosis of PPROM and gestational age from 24 to 35 weeks. Women who presented hypertensive disorders, diabetes, fetuses with birth defects and infection at admission were excluded. To determine the association between AFI and perinatal outcomes, chi-square and Fisher's exact test were used if necessary, as well as risk ratio (RR) and 95% confidence intervals (95CI). Correlation between AFI and perinatal outcomes was determined by using simple linear regression, and AFI progression during pregnancy was analyzed by Z-test.

RESULTS

When comparing newborns presenting ultrasound with AFI<5cm and AFI>5cm, there was a higher frequency of perinatal mortality when the AFI was lower than 5 cm. However, when the oligohydramnios was diagnosed as severe (AFI<3cm), there was a higher frequency of Apgar scores less than seven at 1 minute, neonatal sepsis and early neonatal mortality compared to those presenting AFI>3cm. There was a positive correlation between AFI and gestational age at delivery, birth weight and Apgar scores at minutes 1 and 5. There was also a decrease in amniotic fluid volume with increased gestational age.

CONCLUSION

The presence of severe oligohydramnios after PPROM contributed to a higher frequency of perinatal complications and death.

Effect of magnesium sulfate administration for neuroprotection on latency in women with preterm premature rupture of membranes

OBJECTIVE

This study aims to evaluate whether magnesium sulfate administration for neuroprotection prolongs latency in women with preterm premature rupture of membranes (PPROM) between 24 and 31(6/7) weeks' gestation.

STUDY DESIGN

This is a secondary analysis of a randomized controlled trial of magnesium sulfate for prevention of cerebral palsy. Gravid women with a singleton pregnancy between 24 and 31(6/7) weeks' gestation with PPROM without evidence of labor were randomized to receive magnesium sulfate, administered intravenously as a 6-g bolus followed by a constant infusion of 2 g per hour up to 12 hours, or placebo. Maternal outcomes for this analysis were delivery in less than 48 hours and in less than 7 days from randomization. Neonatal outcomes included a composite of respiratory distress syndrome, interventricular hemorrhage grades 3 or 4, periventricular leukomalacia, sepsis, necrotizing enterocolitis, retinopathy of prematurity, or death.

RESULTS

A total of 1,259 women were included. The rate of delivery < 48 hours was not different in the magnesium sulfate and the placebo groups (22.2 and 20.7%, p = 0.51). Delivery < 7 days was similar between groups (55.4 and 51.4%, p = 0.16). Median latency was also similar between groups (median [interquartile range], 6.0 days [range, 2.4-13.8 days] and 6.6 days [range, 2.4-15.1 days], p = 0.29). Composite neonatal outcomes did not differ between groups.

CONCLUSION

Magnesium sulfate administration given for neuroprotection in women with a singleton gestation with PPROM and without labor before 32 weeks does not impact latency.

Fetal assessment methods for improving neonatal and maternal outcomes in preterm prelabour rupture of membranes

BACKGROUND

Fetal assessment following preterm prelabour rupture of membranes (PPROM) may result in earlier delivery due to earlier detection of fetal compromise. However, early delivery may not always be in the fetal or maternal interest, and the effectiveness of different fetal assessment methods in improving neonatal and maternal outcomes is uncertain.

OBJECTIVES

To study the effectiveness of fetal assessment methods for improving neonatal and maternal outcomes in PPROM. Examples of fetal assessment methods that would be eligible for inclusion in this review include fetal cardiotocography, fetal movement counting and Doppler ultrasound.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 June 2014) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials comparing any fetal assessment methods, or comparing one fetal assessment method to no assessment.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion into the review. The same two review authors independently assessed trial quality and independently extracted data. Data were checked for accuracy.

MAIN RESULTS

We included three studies involving 275 women (data reported for 271) with PPROM at up to 34 weeks' gestation. All three studies were conducted in the United States. Each study investigated different methods of fetal assessment. One study compared weekly endovaginal ultrasound scans with no assessment (n = 93), one compared amniocentesis with no assessment (n = 47), and one compared daily nonstress testing with daily modified biophysical profiling (n = 135). We were unable to perform a meta-analysis, but were able to report data from individual studies.There was no convincing evidence of increased risk of neonatal death in the group receiving endovaginal ultrasound scans compared with the group receiving no assessment (risk ratio (RR) 7.30, 95% confidence interval (CI) 0.39 to 137.54; one study, 92 women), or in the group receiving amniocentesis compared with the group receiving no amniocentesis (RR 1.00, 95% CI 0.07 to 15.00; one study, 44 women). For both these interventions, we inferred that there were no fetal deaths in the intervention or control groups. The study comparing daily nonstress testing with daily modified biophysical profiling did not report fetal or neonatal death. Primary outcomes of maternal death and serious maternal morbidity were not reported in any study. Overall, there were few statistically significant differences in outcomes between the comparisons.The overall quality of evidence is poor, because participant blinding was not possible for any study.

AUTHORS' CONCLUSIONS

There is insufficient evidence on the benefits and harms of fetal assessment methods for improving neonatal and maternal outcomes in women with PPROM to draw firm conclusions. The overall quality of evidence that does exist is poor.Further high-quality randomised controlled trials are required to guide clinical practice.

Dichotomisation of a continuous outcome and effect on meta-analyses: illustration of the distributional approach using the outcome birthweight

BACKGROUND

Power and precision are greater in meta-analyses than individual study analyses. However, dichotomisation of continuous outcomes in certain studies poses a problem as estimates from primary studies can only be pooled if they have a common outcome. Meta-analyses may include pooled summaries of either or both the continuous and dichotomous forms, and potentially have a different combination of studies for each depending on whether the outcome was dichotomised in the primary studies or not. This dual-outcome issue can lead to loss of power and/or selection bias. In this study we aimed to illustrate how dichotomisation of a continuous outcome in primary studies may result in biased estimates of pooled risk and odds ratios in meta-analysis using secondary analyses of published meta-analyses with the outcome, birthweight, which is commonly analysed both as continuous, and dichotomous (low birthweight: birthweight < 2,500 g).

METHODS

Meta-analyses published in January 2010 - December 2011 were obtained using searches in PubMed, Embase, Web of Science, and Cochrane Database of Systematic Reviews with the outcome birthweight. We used a distributional method to estimate the pooled odds/risk ratio of low birthweight and its standard error as a function of the data reported in the primary studies of the included meta-analyses where accessible.

RESULTS

Seventy-six meta-analyses were identified. Thirty-seven percent (28/76) of the meta-analyses reported only the dichotomous form of the outcome while 26% (20/76) reported only the continuous form. In one meta-analysis (1/76), birthweight was analysed as continuous for one intervention and as binary for another and 36% (27/76) presented both dichotomous and continuous birthweight summaries. In meta-analyses with a continuous outcome, primary studies data were accessible in 39/48 and secondary analyses using the distributional approach provided consistent inferences for both the continuous and distributional estimates in 38/39.

CONCLUSION

The distributional method applied in primary studies allows both a continuous and dichotomous outcome to be estimated providing consistent inferences. The use of this method in primary studies may restrict selective outcome bias in meta-analyses.

Tocolytics for preterm premature rupture of membranes

BACKGROUND

In women with preterm labor, tocolysis has not been shown to improve perinatal mortality; however, it is often given for 48 hours to allow for the corticosteroid effect for fetal maturation. In women with preterm premature rupture of membranes (PPROM), the use of tocolysis is still controversial. In theory, tocolysis may prolong pregnancy in women with PPROM, thereby allowing for the corticosteroid benefit and reducing the morbidity and mortality associated with prematurity.

OBJECTIVES

To assess the potential benefits and harms of tocolysis in women with preterm premature rupture of membranes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (15 January 2014).

SELECTION CRITERIA

We included pregnant women with singleton pregnancies and PPROM (23 weeks to 36 weeks and six days). We included any tocolytic therapy compared to no tocolytic, placebo, or another tocolytic.

DATA COLLECTION AND ANALYSIS

All review authors assessed the studies for inclusion. We extracted and quality assessed data.

MAIN RESULTS

We included eight studies with a total of 408 women. Seven of the studies compared tocolysis to no tocolysis. One study compared nifedipine to terbutaline. Compared to no tocolysis, tocolysis was not associated with a significant effect on perinatal mortality in women with PPROM (risk ratio (RR) 1.67; 95% confidence interval (CI) 0.85 to 3.29). Tocolysis was associated with longer latency (mean difference (MD) 73.12 hours; 95% CI 20.21 to 126.03; three trials of 198 women) and fewer births within 48 hours (average RR 0.55; 95% CI 0.32 to 0.95; six trials of 354 women; random-effects, Tau² = 0.18, I² = 43%) compared to no tocolysis. However, tocolysis was associated with increased five-minute Apgar of less than seven (RR 6.05; 95% CI 1.65 to 22.23; two trials of 160 women) and increased need for ventilation of the neonate (RR 2.46; 95% CI 1.14 to 5.34; one trial of 81 women). In the subgroup analysis comparing betamimetic to no betamimetics, tocolysis was associated with increased latency and borderline significance for chorioamnionitis. Prophylactic tocolysis with PPROM was associated with increased overall latency, without additional benefits for maternal/neonatal outcomes. For women with PPROM before 34 weeks, there was a significantly increased risk of chorioamnionitis in women who received tocolysis. However, neonatal outcomes were not significantly different. There were no significant differences in maternal/neonatal outcomes in subgroup analyses comparing cox inhibitor versus no tocolysis, calcium channel blocker versus betamimetic, antibiotic, corticosteroid or combined antibiotic/corticosteroid.

AUTHORS' CONCLUSIONS

Our review suggests there is insufficient evidence to support tocolytic therapy for women with PPROM, as there was an increase in maternal chorioamnionitis without significant benefits to the infant. However, studies did not consistently administer latency antibiotics and corticosteroids, both of which are now considered standard of care.

Prevention of periviable birth: bed rest, tocolysis, progesterone, and cerclage

The periviable period is associated with a rapid improvement in both mortality and morbidity with increasing gestational age. Therapies that can prolong gestation have the potential for markedly improving outcome compared to later in pregnancy. The therapies commonly prescribed in order to prolong gestation include bed rest, tocolysis, progesterone, and cerclage. Although these therapies are used to prevent preterm birth throughout gestation, their impact on perinatal outcome during the periviable period remains largely unknown. These therapies are discussed relative to the periviable period exploring available data and possible impact on perinatal outcome. Studies specifically evaluating therapeutic interventions during the periviable period are lacking.

Hydration for treatment of preterm labour

BACKGROUND

Hydration has been proposed as a treatment for women with preterm labour. Theoretically, hydration may reduce uterine contractility by increasing uterine blood flow and by decreasing pituitary secretion of antidiuretic hormone and oxytocin.

OBJECTIVES

To evaluate the effectiveness of intravenous or oral hydration to avoid preterm birth and its consequences in women with preterm labour.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 September 2013) and bibliographies of relevant papers.

SELECTION CRITERIA

Randomised controlled trials, including women with a viable pregnancy less than 37 completed weeks' gestation and presenting with preterm labour, comparing intravenous or oral hydration with no treatment. The intervention might or might not be associated with bed rest. Studies comparing tocolytic drugs with intravenous fluids used in the control group as a placebo were not included in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the reports, to determine if the study met the inclusion criteria and to evaluate the methodological quality. Data were extracted independently by two of the review authors. The results were expressed as risk ratios (RR) for dichotomous outcomes and mean difference (MD) for continuous outcomes.

MAIN RESULTS

Two studies, including a total of 228 women with preterm labour and intact membranes, compared intravenous hydration with bed rest alone. Risk of preterm delivery, before 37 weeks (RR) 1.09; 95% confidence interval (CI) 0.71 to 1.68), before 34 weeks (RR 0.72; 95% CI 0.20 to 2.56) or before 32 weeks (RR 0.76; 95% CI 0.29 to 1.97), was similar between groups. Admission to neonatal intensive care unit occurred with similar frequency in both groups (RR 0.99; 95% CI 0.46 to 2.16). Cost of treatment was slightly higher (US$39) in the hydration group. This difference was not statistically significant and only includes hospital costs during a visit of less than 24 hours. No studies evaluated oral hydration.

AUTHORS' CONCLUSIONS

The data are too few to support the use of hydration as a specific treatment for women presenting with preterm labour. The two small studies available do not show any advantage of hydration compared with bed rest alone. Intravenous hydration does not seem to be beneficial, even during the period of evaluation soon after admission, in women with preterm labour. Women with evidence of dehydration may, however, benefit from the intervention.

Role of aldo-keto reductase enzymes in mediating the timing of parturition

A better understanding of the mechanisms underlying parturition would provide an important step toward improving therapies for the prevention of preterm labor. Aldo–keto reductases (AKR) from the 1D, 1C, and 1B subfamilies likely contribute to determining the timing of parturition through metabolism of progesterone and prostaglandins. Placental AKR1D1 (human 5β reductase) likely contributes to the maintenance of pregnancy through the formation of 5β-dihydroprogesterone (DHP). AKR1C1, AKR1C2, and AKR1C3 catalyze the 20-ketosteroid and 3-ketosteroid reduction of progestins. They could therefore eliminate tocolytic progestins at term. Activation of the F prostanoid receptor by its ligands also plays a critical role in initiation of labor. AKR1C3 and AKR1B1 have prostaglandin (PG) F synthase activities that likely contribute to the initiation of labor. AKR1C3 converts PGH₂ to PGF_2α and PGD₂ to 9α,11β-PGF₂. AKR1B1 also reduces PGH₂ to PGF_2α, but does not form 9α,11β-PGF₂. Consistent with the potential role for AKR1C3 in the initiation of parturition, indomethacin, which is a potent and isoform selective inhibitor of AKR1C3, has long been used for tocolysis.