Risk factors for meconium aspiration syndrome

To identify potential predictors of meconium aspiration syndrome (MAS) in pregnancies complicated by moderate or thick meconium-stained amniotic fluid (AF).

In the period 1990-1993, 937 vertex singleton pregnancies with moderate or thick meconium-stained AF were delivered; of these, 39 neonates developed MAS and 898 did not. The two groups were compared retrospectively according to maternal findings, pregnancy outcome, and neonatal complications, using univariate analysis (P < .05 considered significant) and stepwise multiple logistic regression analysis to identify independent significant factors for prediction of MAS and to calculate odds ratios (OR) and 95% confidence intervals.

The two groups had a similar mean gestational age at delivery and birth weight. They also had similar incidences of post-dates pregnancies, small and large for gestational age infants, and amnioinfusion use. Univariate analysis identified significant differences between the two groups in 13 variables, two of which were excluded from logistic analysis because of inadequate data. Logistic regression analysis identified only six variables with independent, statistically significant effects on MAS: admission for induction with nonreassuring fetal heart tracing (OR 6.9), need for endotracheal intubation and suctioning below the vocal cords (OR 4.9), 1-minute Apgar score of 4 or less (OR 3.1), present cesarean delivery (OR 3.0), and previous cesarean delivery (OR 2.5). Cigarette smoking was associated with a lower risk for MAS (OR 0.07). The presence of at least one of the five risk factors had a sensitivity of 92%, a specificity of 56%, a positive predictive value of 8%, and a negative predictive value of 99% for MAS.

Considering the high negative predictive value of the test, infants without any risk factors will not develop MAS and thus can be safely allowed to room with their mothers. Furthermore, this model helps to identify infants who may benefit from 24-hour observation and in counseling women about the neonatal risk for developing MAS.