Predictors of adverse neonatal outcomes in low-risk nulliparous women at term with meconium-stained amniotic fluid

Meconium-stained amniotic fluid (MSAF) has been linked to adverse neonatal outcomes, but most evidence comes from heterogeneous cohorts that included multiparous and high-risk women. Nulliparous women without comorbidities are generally considered low risk, yet their outcomes in the presence of MSAF remain less well defined. This study aimed to identify predictors of adverse neonatal outcomes in low-risk nulliparous women at term with MSAF.

A retrospective cohort study.

Seven hundred sixty low-risk nulliparous women with documented MSAF at term delivery between March 2020 and July 2024.

A tertiary, university-affiliated medical center.

Obstetric and neonatal data were extracted from electronic medical records. Maternal, intrapartum, and neonatal characteristics were compared between women with and without an adverse neonatal outcome. The latter was defined as the presence of at least one of the following: a 5-min Apgar score < 7, umbilical artery pH < 7.15, admission to the neonatal intensive care unit, the need for invasive ventilation, meconium aspiration syndrome, or neonatal death. Multivariable logistic regression was performed to identify independent predictors of adverse outcome.

Among women with adverse neonatal outcomes (59, 7.8%) compared to those without adverse outcomes, the mean delivery was earlier (39.3 ± 2.5 vs 40.0 ± 1.0 weeks, p < 0.001) and the mean birthweight lower (3171.8 ± 698.8 g vs 3328.7 ± 413.2 g, p = 0.009). Prolonged rupture of membranes > 18 h was more common (11.9% vs 3.0%, p = 0.004), as was chorioamnionitis (22.0% vs 10.6%, p = 0.012). Meconium thickness was greater (p = 0.049). In multivariable logistic regression, early term delivery (adjusted odds ratio (aOR) 3.63, 95% CI 1.76-7.51), prolonged rupture of membranes > 18 h (aOR 4.27, 95% CI 1.93-9.47), moderate meconium (aOR 2.46, 95% CI 1.29-4.69), thick meconium (aOR 4.67, 95% CI 2.00-10.91), and chorioamnionitis (aOR 2.74, 95% CI 1.52-4.93) were independent predictors of an adverse neonatal outcome.

The retrospective single-center design and limited number of adverse neonatal events may restrict generalizability and preclude assessing risks for specific morbidities.

Among low-risk nulliparous women with MSAF, early term delivery, prolonged rupture of membranes, greater meconium thickness, and chorioamnionitis were associated with adverse neonatal outcomes. These factors may assist in predicting risk and guiding intrapartum management, though validation in larger prospective studies is needed.