Can maternal characteristics on admission for preterm prelabor rupture of membranes predict pregnancy latency?

Abstract

Latency duration after preterm prelabor rupture of membranes has been an area of investigation for many years. Previously described factors associated with latency include gestational age at the time of rupture, cervical dilation of >1 cm, vaginal bleeding at the time of presentation, and oligohydramnios. However, little is known about the impact of composite maternal factors and presenting symptoms on the duration or prediction of the latency period. This study aimed to determine whether maternal factors and subjective presenting symptoms can predict pregnancy latency after preterm prelabor rupture of membranes. This is a retrospective observational study of singleton pregnancies complicated by preterm prelabor rupture of membranes for over 3 years at a single institution utilizing a uniform management protocol. Maternal demographics, obstetrical data, maternal subjective symptoms and physical examination findings on admission, amniotic fluid volume assessment, presence of contractions, and maternal perception of feeling unwell were collected and analyzed. Clinical characteristics were summarized with mean and standard deviation for continuous measures and frequency and percentages for categorical variables. For skewed variables, medians with 25th and 75th percentiles were reported. Cumulative latency duration (ie, survival time) was estimated with a Kaplan-Meier model. Multivariable Cox proportional hazards regression model with backward variable selection was used to determine the effects of maternal factors on latency duration. Of the 212 patients available for analysis, there was a considerable variability in the latency duration with values ranging between 0 and 119 days. Factors related to latency duration included maternal age, parity, gestational age at rupture, cervical dilation, amniotic fluid volume, and contractions. Advancing maternal age (P=.012), increased gestational age at rupture (P<.0001), cervical dilation of ≥3 (vs 0; P<.0001), anhydramnios or oligohydramnios (vs normal amniotic fluid; P<.0001), cramping (P=.012), and painful contractions (P=.015) were associated with a shorter latency duration. Utilizing these statistically significant factors, we constructed a nomogram to predict latency for 1-day, 1-week, and overall median latency duration. Maternal factors and presenting symptoms can predict pregnancy latency after preterm prelabor rupture of membranes. We created a nomogram for clinical use that provides a visual display of the probability of pregnancy latency. This tool may be useful for counseling and providing additional information on expectations for providers and patients with pregnancies complicated by preterm prelabor rupture of membranes.