Relationship between meconium staining and amniotic fluid volume in term pregnancies.

OBJECTIVE: Our purpose was to evaluate the relationship between meconium-stained amniotic fluid (MEC-AF) and amniotic fluid volume (AFV) and their impact on the risk of cesarean delivery for fetal indications in term pregnancies.

METHODS: 1,655 live-born singleton gestations delivering at > or = 37 weeks within 7 days of sonographic assessment of the amniotic fluid index (AFI) were studied. AFI was categorized as: oligohydramnios (< or = 5.0 cm); decreased (5.1-8.0 cm); normal (8.1-18.0 cm); increased (18.1-23.9 cm), and polyhydramnios (> or = 24.0 cm). Frequencies of MEC-AF for each AFV category were stratified by gestational age (GA) and rates of cesarean delivery for fetal indications compared between patients with clear amniotic fluid and those with MEC-AF. Stepwise logistic regression analyses were performed for determinants of MEC-AF and the need for cesarean delivery for fetal indications.

RESULTS: The frequency of MEC-AF at birth in term pregnancies was not related to AFV: oligohydramnios (16.7%); decreased (16.7%); normal (20.1%); increased (24.4%), and polyhydramnios (22.1%). The only factor associated with the occurrence of MEC-AF was increasing GA at delivery (p < 0.01). Both MEC-AF (p < 0.02) and decreasing neonatal ponderal index (p < 0.02) were independently associated with cesarean delivery for fetal distress.

CONCLUSIONS: MEC-AF does not appear to be related to AFV in term pregnancies, and its presence increases the risk of cesarean delivery for fetal distress independent of AFV and neonatal ponderal index.