Association between latency period and perinatal outcomes after preterm premature rupture of membranes at 32-37 weeks of gestation: a perinatal registry-based cohort study

Objectives To investigate association between latency after preterm premature rupture of membranes (PPROM) and perinatal outcomes at moderately and late preterm gestation. Methods National perinatal registry-based cohort study using data for the period 2013-2018. Singleton pregnancies with non-malformed fetuses in cephalic presentation complicated by PPROM at 32(+0)-36(+6) weeks were included. Associations between latency period and perinatal mortality, neonatal respiratory distress syndrome (RDS), early onset neonatal infection (EONI), and cesarean section were assessed using multiple logistic regression, adjusting for potential confounders (labor induction, maternal body-mass-index, maternal age, antenatal corticosteroids, and small-for-gestational-age). pResults Of 3,017 pregnancies included, 365 (12.1%) had PPROM at 32(+0)-33(+6) weeks and 2,652 (87.9%) at 34(+0)-36(+6) weeks. Among all cases, 2,540 (84%) had latency <24 h (group A), 305 (10%) 24-47 h (group B), and 172 (6%) >= 48 h (group C). Longer latency was associated with higher incidence of EONI (adjusted odds ratio [aOR] 1.350; 95% confidence interval [CI] 0.900-2.026 for group B and aOR 2.500; 95% CI 1.599-3.911 for group C) and higher rate of caesarean section (aOR 2.465; 95% CI 1.763-3.447 for group B and aOR 1.854; 95% CI 1.172-2.932 for group C). Longer latency was not associated with rates of RDS (aOR 1.160; 95% CI 0.670-2.007 for group B and aOR 0.917; 95% CI 0.428-1.966 for group C). Conclusions In moderately to late PPROM, increased latency is associated with higher risk of EONI and cesarean section with no reduction in RDS.