Preterm meconium-stained amniotic fluid: A red flag for infection and adverse perinatal outcomes

Meconium-stained amniotic fluid (MSAF) is uncommon in preterm deliveries and raises concerns about maternal and neonatal infectious risks. We aimed to evaluate maternal, perinatal, and microbiological outcomes in preterm deliveries complicated by MSAF compared to clear amniotic fluid (AF) and to assess outcomes in preterm versus term deliveries with MSAF.

This retrospective cohort study included singleton pregnancies delivered at 24-42 weeks at a tertiary hospital (March 2020-May 2024), with documented AF color. Chorioamniotic swab culture results were analyzed, and clinical outcomes compared using univariate and multivariate analyses.

Of 1550 preterm deliveries, 93 (6%) were complicated by MSAF. For preterm births with MSAF compared to AF, the rates were higher of clinical chorioamnionitis, puerperal endometritis, maternal bacteremia, and adverse neonatal outcomes, including respiratory distress syndrome and the need for ventilation (P < 0.001 for all). Positive chorioamniotic swab cultures were more frequent in preterm MSAF than preterm clear AF (26 [28.0%] vs. 168 [11.5%], P < 0.001), with higher isolation of Enterobacteriaceae (P = 0.030) and group B streptococcus (GBS; P = 0.040). Comparing preterm versus term deliveries, among those complicated by MSAF, the rates were higher of clinical chorioamnionitis, endometritis, maternal bacteremia, early-onset sepsis, and positive chorioamniotic cultures (26 [28.0%] vs. 220 [10.0%], P < 0.001), particularly Enterobacteriaceae (P = 0.001) and Enterococcus spp. (P = 0.003).

Preterm deliveries with MSAF, compared to preterm clear AF and term MSAF, were associated with increased maternal infections, neonatal morbidity, and distinct microbial colonization. Chorioamniotic swab cultures might aid in identifying high-risk preterm births requiring targeted infection management.