Prognostic value of change in amniotic fluid color during labor

Evidence of meconium-stained amniotic fluid (AF) during labor suggests implementation of close monitoring of fetal well-being. We have investigated whether the presence of meconium in the AF on admission for labor is as important a predictor of neonatal outcome as a change in AF color during labor.

AF characteristics on admission for labor at term (37-42 weeks) and their changes during labor were recorded in all singleton pregnancies during an 8-year period (1992-1999). Excluded were stillbirths on admission, congenital anomalies, and elective cesarean sections. The presence of meconium and its consistency (light or thick) were documented on admission by inspection with transcervical amnioscopy in women with intact membranes or in the vaginal pool in those with ruptured membranes. Changes in AF color or consistency during labor were recorded and correlated with the obstetric and neonatal outcome. Statistical analysis utilized chi(2) for trend, with p < 0.05 considered significant.

19,090 women were admitted in labor at term during the study period and fulfilled the study inclusion criteria and had amniotic fluid evaluation available. The appearance of meconium or worsening in thickness of meconium during labor was associated with higher rates of Apgar scores <7 at 5 min (clear AF on admission and at delivery 0.6%; light or thick meconium on admission and no change at delivery 0.8%; clear AF on admission and light or thick meconium at delivery 3.2%, and light meconium on admission and thick meconium at delivery 2.5%; p < 0.001) and umbilical artery pH <7.10 (the respective rates in the four groups were 1.7, 1.8, 3.6, and 3.8%; p < 0.001).

The appearance or thickening of meconium during labor has a greater predictive ability for depressed neonates than the presence of meconium on admission.