Prolonged exposure to meconium in cases of spontaneous premature rupture of membranes at term and pregnancy outcome

Abstract

Objective: To evaluate the impact of prolonged exposure to meconium-stained amniotic fluid (MSAF), in women with term pre-labor spontaneous rupture of membranes (PROM), on pregnancy outcome.

Methods: A retrospective cohort study of women who gave birth in a single university-affiliated tertiary medical center (2011-2019). Eligibility was limited to singleton pregnancies at term who presented with PROM. Women with MSAF were immediately induced and were compared to low-risk pregnant women with clear amniotic fluid (CAF) at admission who underwent induction of labor 24 h after rupture of membranes. All women were stratified into 4-time frame groups from rupture of membranes to delivery: T0: 0-7 h, T1: 8-13 h, T2: 14-18 h, and T3: > 18 h for the MSAF group. The time frames for the CAF were: T0 - 24-31 h, T1: 32-38 h, T2: 40-44 h, and T3: > 44 h. The maternal adverse composite outcome included any of the following: intrapartum fever (IPF), prolonged second stage (PSS), need for manual removal of suspected retained placenta, postpartum hemorrhage, and readmission within 45 days after delivery. The adverse composite neonatal outcome included one or more of the following: meconium aspiration syndrome, neonatal asphyxia, need for respiratory support, and intracranial hemorrhage.

Results: Overall, 1631 women met the inclusion criteria (536 in the MSAF and 1095 in the CAF group). Both groups showed a gradual decrease in the rate of vaginal delivery over time, the vaginal delivery rate in the MSAF group was 75.7% at T0 in comparison to 61.6% at T3 (p < .001). In the CAF group, the vaginal delivery rate was 84.5% at T0 in comparison to 68.8% at T3 (p < .001). This decrease was in concomitance with an increase in the rates of prolonged second-stage and intrapartum fever. There were no significant differences in the rates of postpartum hemorrhage, suspected retained placenta, or readmission within 45 days between women with either MSAF or CAF. There was a significant gradual increase in the adverse composite neonatal outcome in the MSAF group (1.9% at T0, 5.2% at T1, 6.0% at T2, and 8.2% at T3. p = .038). No similar increase was found in the CAF group (2.5% at T0, 4.1% at T1, 2.6% at T2, and 4.1% at T3. p = .449).

Conclusion: Prolonged rupture of membranes in the presence of meconium does not affect maternal outcomes, however, prolonged exposure to meconium lead to an increased adverse neonatal outcome.

Keywords: Amniotic fluid; maternal outcome; meconium; neonatal outcome; prolonged rupture of membranes.