Objective: To determine the risk of adverse neonatal outcome associated with meconium-stained amniotic fluid independent of that related to antepartum or intrapartum abnormalities.
Methods: A cohort of 2200 consecutive deliveries was examined and the fetal heart rate (FHR) tracings analyzed independently. Singleton term pregnancies without fatal malformations were stratified by the consistency of meconium and compared.
Results: Moderate or thick meconium increased the risk for adverse outcome more than threefold (relative risk 3.2, 95% confidence interval 2.0-5.2). This risk was independent of fetal heart tracing abnormalities or maternal hypertensive, kidney, or heart disease.
Conclusion: Thick meconium alone should alert the physician to a high-risk fetal condition. This phenomenon requires continuous FHR monitoring and reassurance of fetal well-being by acid-base assessment or the equivalent, regardless of maternal disease status or the presence of abnormal FHR tracings.