Risk factors for meconium stained amniotic fluid and its implications

Background: Meconium staining of amniotic fluid (MSAF) has for long been considered to be a predictor of adverse fetal outcome and meconium aspiration syndrome (MAS), a major cause of perinatal morbidity and mortality. The aim of the study was to identify the risk factors, perinatal outcome in deliveries complicated by meconium stained amniotic fluid.Methods: This study is a prospective case control study of 100 patients done in a tertiary care hospital over a period of six months. Fifty patients with meconium stained amniotic fluid detected at any time during the course of labour or prior to it were enrolled in the study group. The inclusion criteria for the study were, a singleton pregnancy, cephalic presentation, term gestation and absence of major congenital anomalies. For the control group, the next woman giving birth following the index patient who satisfied the same set of inclusion criteria and had clear amniotic fluid was selected. Data was collected on a standardized pretested proforma.Results: Gestational age and parity showed no statistical significance between the study and control groups. Among antepartum and intrapartum risk factors, preeclampsia (32% in the study group vs 6% in the control group) p=0.0034, fetal growth restriction (12% vs 2%) p=0.05, fetal distress (36% vs 6%) p=0.0002 and labour dystocia (20% vs none in the control group) p=0.0009 were found to be statically significant. Caesarean section was considerably higher in patients with meconium stained amniotic fluid (66% vs 28%), p=0.0004. 3 (66%) patients had thin meconium and 17 patients (34%) had thick meconium stained amniotic fluid. Eighteen percent of the babies with meconium stained amniotic fluid had an Apgar of less than 7 at 5 minutes. Thirteen (26%) of the babies with meconium stained amniotic fluid developed MAS.Conclusions: Meconium stained amniotic fluid is associated with a higher incidence of operative deliveries resulting in an increased maternal morbidity. It is also associated with an increased neonatal morbidity due to birth asphyxia and respiratory depression at birth and a significant risk of neonatal mortality due to meconium aspiration syndrome.