I have often wondered why my obstetrical colleagues would often induce labour once a woman with ruptured membranes reached 34 weeks. I wasn't aware of any data to support doing this, or, on the other hand, any good data to say that you shouldn't.

It turns out that I was well-informed, there just wasn't any good data, until now. Morris JM, et al. Immediate delivery compared with expectant management after preterm pre-labour rupture of the membranes close to term (PPROMT trial): a randomised controlled trial. Lancet. 2015;387(10017):444-52. In this study over 1800 women with singleton pregnancies and ruptured membranes without labour, who were between 34 and 37 weeks gestation, were randomized to either immediate delivery (induction or cesarean) or expectant management, in which case the woman and her obstetrician waited for spontaneous labour or another indication to deliver. Women whose membranes ruptured before 34 weeks became eligible when they hit that mark.

This remarkable study took 10 years to recruit their subjects. It was run out of Sydney, and funded by the NHMRC of Australia and enrolled mothers from 11 different countries.

What did they find? Well, neonatal sepsis occurred in 23 (2%) of the babies in the immediate delivery group, 29 (3%) of the expectant group, a difference which could easily be due to chance. There were 3 neonatal deaths in each group. On the other hand, expectantly managed pregnancies ended up with a significantly higher gestational age and birthweight, not surprisingly, and as a result less NICU admission, less respiratory distress, less assisted ventilation,  and fewer days in hospital, all of which were highly statistically significant. For the mothers there were some downsides, there was a slight increase in  antepartum or intrapartum haemorrhage from 3% to 5% and they had one day more of hospital stay with expectant management, but they had many fewer cesarean deliveries. 19% in the expectant group compared to 26%.

This is very high quality evidence that we should not be doing what ACOG currently states, which is to deliver immediately because of the risk of neonatal sepsis. If things are going well, and there is no sign of infection, pre-labour preterm rupture of membranes can be followed closely, with delivery for other obstetric indications.