Delivery Room Risk Factors for Meconium Aspiration Syndrome

The objective of this study is to identify risk factors for meconium aspiration syndrome (MAS) in newborns born through meconium-stained amniotic fluid (MSAF). From May 27, 1994 to June 9, 1997 maternal and neonatal data were prospectively collected on all infants born through MSAF. Development of MAS was the primary outcome. Using bivariate and logistic regression analysis we identified risk factors for MAS. There were 8,967 births during this period: 7.9% (708 of 8,967) were delivered through MSAF. Respiratory symptoms developed in 6.8% (48 of 708) of births. Of these, 50% (24 of 48) were excluded due to the diagnosis of transient tachypnea of the newborn (17), respiratory distress syndrome (4), group B streptococcus pneumonia (1), congenital cytomegalic inclusion disease (1), and supraventricular tachycardia (1). Of the 24 infants with respiratory symptoms consistent with MAS, 45.8% (11 of 24) required ventilatory support, one required extracorporeal-membrane oxygenation. Bivariate analysis identified six risk factors ( p <0.05): Apgar <7 at 1 minute, Apgar <7 at 5 minutes, thick meconium, fetal distress, suction of infant's stomach by delivery room team at <5 minutes of age, and need for resuscitation. Tracheal meconium was very prevalent in our population at 74% of all intubated infants, and was not significantly associated with MAS. Logistic regression analysis identified four independent risk factors. Looking at multiple prediction models, an infant with fetal distress, Apgar <7 at 1 and 5 minutes and thick meconium has a 79.8% probability of developing respiratory symptoms. If these risk factors are not present, there is a 0.8% risk. In our cohort, this group had 16.7% positive predictive value (4 of 24) and 99.6% negative predictive value (657 of 660). In meconium deliveries, infants with thick meconium, fetal distress, and Apgar scores <7 at 1 and 5 minutes are at high risk for development of respiratory symptoms. Infants delivered in the absence of all of these risk factors are at low risk for development of MAS.