Amniotic fluid transitioning from clear to meconium stained during labor—prevalence and association with adverse maternal and neonatal outcomes

Objective The objective of this study is to compare pregnancy outcomes in deliveries complicated by primary meconium-stained amniotic fluid (MSAF, present at membrane rupture) and secondary MSAF (transitioned from clear to MSAF during labor). Methods The medical records and neonatal charts of all deliveries ≥ 37 0/7 weeks between October 2008 and July 2018 were reviewed. The primary outcome was composite adverse neonatal outcome that included early neonatal complications. Results Of 30,215 deliveries during the study period, 4302 (14.2 %) were included: 3845 (89.4%) in the primary MSAF group and 457 (10.6%) in the secondary MSAF group. The rate of the primary outcome was higher in the secondary MSAF group ( p = 0.006). This association remained significant after controlling for background confounders. The secondary MSAF group had higher rate of cesarean deliveries (CDs) and assisted vaginal deliveries. There was a higher rate of composite adverse neonatal outcome when secondary MSAF was diagnosed < 3 vs. >3 h before delivery ( p = 0.004). Conclusion Secondary MSAF was associated with higher rates of adverse neonatal outcome, CDs, and assisted vaginal deliveries, compared with primary MSAF.