Fetal assessment methods after preterm prelabour rupture of membranes for improving outcomes for mothers and babies

In a small number of pregnancies, the sac (membranes) surrounding the baby ruptures preterm, before 37 weeks of gestation, and before onset of labour. Preterm prelabour rupture of membranes (PPROM) occurs in around a third of all preterm births but the cause is often unknown. PPROM can result in illness and death for both the mother and baby through complications such as compression of the umbilical cord and bacteria infecting the uterus. The biggest problem for the baby is an increased risk of respiratory distress, brain haemorrhage and infection because of being born early. Several methods are available for assessing the wellbeing of the unborn baby following PPROM, to help healthcare providers detect any problems with the baby and make decisions on whether to deliver the baby earlier that they otherwise would. Most women will go into spontaneous labour within several days of PPROM.

This review was carried out to evaluate whether these methods lead to improved health outcomes for the mother and her baby. The review included three randomised controlled studies that involved a total of 275 women (data reported for 271) with PPROM at up to 34 weeks' gestation. All three studies were from the USA. They each investigated different methods of fetal assessment, so no meta-analysis could be conducted. Instead, the review reported the results of each individual study. One study compared weekly endovaginal ultrasound scans where the probe is placed inside the vagina versus no assessment, one compared an amniotic fluid test to measure levels of fetal lung surfactant with no assessment, and one compared a daily 'nonstress test' (recording the fetal heartbeat) with daily modified biophysical profiling (recording the fetal heartbeat as well as estimating the volume of amniotic fluid surrounding the baby). In each study, there were few statistically significant differences between groups in outcomes for the mother, fetus or neonate. The overall quality of the evidence was poor, because participants knew which group they were in. More studies are needed to assess the benefits and harms of fetal assessment methods for improving neonatal and maternal outcomes in women with PPROM before firm conclusions can be drawn.

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.

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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 strategy: 

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.

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