Objective: To evaluate the association between latency and neonatal morbidity for pregnancies with expectant management of PPROM ≥34 w.
Materials and methods: A retrospective cohort of singletons with PPROM from 2011 to 2016. Exposure was defined as latency (period from diagnosis of PPROM to delivery) and was analyzed as a count variable (i.e. number of days) and binary variable (≥7 days and <7 days; ≥21 days and <21 days). Primary outcome was composite neonatal morbidity defined as need for respiratory support, culture positive neonatal sepsis, and/or neonatal antibiotics >72 h. Fisher's exact test, chi-square test, Mann-Whitney U and binary logistic regression tests were performed with p<.05 considered significant.
Results: Of 813 pregnancies, 104 met inclusion criteria: 73 (70.2%) pregnancies with PPROM diagnosed at <34 weeks and 31 (29.8%) pregnancies with PPROM diagnosed ≥34 weeks. A total of 58 (55.8%) pregnancies had a latency of ≥7 days and 46 (44.2%) had a latency <7 days. There was no difference in composite neonatal morbidity for latency ≥7 d versus <7 d (aOR 0.92; 95% CI 0.30-2.82) or latency as a count variable (aOR 0.70; 95% CI 0.23-2.13). However, a latency ≥21 d was associated with increased composite neonatal morbidity (aOR 10.24, 95% CI 1.42-73.99).
Conclusion: In pregnancies with PPROM expectantly managed ≥34 w, a latency of ≥7 d is not associated with significant differences in neonatal morbidity. However, different latency thresholds may be more clinically relevant for late preterm pregnancies. The increase in composite neonatal morbidity associated with a latency >21 days should be an area of future investigation and may suggest there is a population of pregnancies with PPROM which may not benefit from expectant management past 34 weeks.
Keywords: Preterm prelabor rupture of membranes; late preterm; latency.