Amniotic fluid abnormalities.

The complex nature of amniotic fluid reflects contributions from many fetal systems, many functional roles, and multiple interactions with fetal maturation, obstetric, and maternal factors. Simple ultrasound measurement, probably done best with the maximum vertical pocket method, has a clinical role in fetal surveillance, substantiated by extensive level II and some level I evidence. Interventions (amnioinfusion for oligohydramnios, amnioreduction for polyhydramnios) have not been studied effectively in controlled fashion, with the exception of intrapartum applications, where effective reduction of cesarean delivery for fetal distress and perinatal impacts of meconium aspiration may follow amnioinfusion. A wealth of research opportunities exists into regulation of amniotic fluid constituents and their relation to preterm delivery.