Amniotic fluid (AF) is a complex substance essential to fetal well-being. This article reviews recent discoveries and the current understanding of the origin and circulation of AF and its nutritive, protective, and diagnostic functions. Future directions for AF research are also discussed.

The rate of intracranial hemorrhage is higher among infants delivered by vacuum extraction, forceps, or cesarean section during labor than among infants delivered spontaneously, but the rate among infants delivered by cesarean section before labor is not higher, suggesting that the common risk factor for hemorrhage is abnormal labor.

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Prematurity, whether examined by gestational age or birth weight, is associated with significant neonatal hospital costs, all of which decrease exponentially with advancing gestational age. Because total costs for each gestational age group from 25 to 36 weeks were roughly the same (38,000,000 dollars), opportunity for intervention to prevent preterm delivery and decrease costs is potentially available at all preterm gestational ages.

Nulliparous women age 40 or over have a higher risk of operative delivery (cesarean, forceps, and vacuum deliveries: 61%) than do younger nulliparous women (35%). This increase occurs in spite of lower birth weight and gestational age and may be explained largely by the increase in other complications of pregnancy. The increased frequency at which white women are having their first child at age 40 or over may reflect career choices that involve delaying childbirth until the fifth decade of life. These data will allow us better to counsel patients about their pregnancy expectations and possible outcomes.