Thromboplastic activity of amniotic fluid in term and postmature gestations.

The danger to the newborn inherent in a postmature pregnancy has gained recognition. However, the diagnosis of postmaturity remains a difficult problem. The thromboplastic activity of amniotic fluid (TAAF) increases with the gestational age. Based on this phenomenon, the TAAF of 45 women in the 41st to 43rd weeks of gestation was established, using their amniotic fluid as a source of thromboplastin. It was found that in all cases in which the TAAF value was less than 42 seconds, the newborns exhibited clinical evidence of postmaturity.