Impact of Primary Versus Secondary Grade III Meconium-Stained Amniotic Fluid on Maternal and Neonatal Outcomes: A Retrospective Single-Center Study

Background: Secondary meconium-stained amniotic fluid (MSAF) is reportedly associated with adverse maternal and neonatal outcomes. In this study, we aimed to investigate the differences in maternal and neonatal outcomes between primary and secondary Grade III MSAF patients. Methods: This retrospective analysis enrolled women who experienced Grade III MSAF during childbirth between September 2020 and June 2023 in our hospital. We collected and compared the baseline characteristics, as well as maternal and neonatal outcomes, between the primary and secondary cases. For parameters with significant statistical differences and clinical significance, we performed multivariable logistic regression analysis to explore potential risk factors for secondary MSAF. Results: A total of 517 patients with Grade III MSAFs were included in the study. We found no significant difference in neonatal outcomes between the primary and secondary groups. More primary grade III MASFs occurred in the first stage of labor (53.1% vs. 28.8%, p < 0.001). A greater percentage of patients who underwent cesarean section (28.8% vs. 17.5%, p = 0.001) were in the primary group. More women with intrapartum fever were in the secondary group (19.8% vs. 28.1%, p = 0.027), but there was no significant difference in laboratory routine blood test results. This association remained significant after controlling for background confounders. However, when combined with an abnormal fetal heart rate (FHR) pattern, both the primary (9.0% vs. 33.3%, p < 0.001) and secondary (12.6% vs. 25.0%, p = 0.009) groups had increased rates of neonatal intensive care unit (NICU) admission. Conclusions: Primary Grade III MSAF is associated with an increased rate of cesarean delivery, while Grade III MSAF elevates the risk of intrapartum fever. Secondary Grade III MSAF alone does not increase the risk of NICU admission, but the presence of an abnormal FHR is a significant indicator.