Amniotic fluid infections with intact membranes leading to perinatal death: a prospective study.

The pathogenesis of fatal amniotic fluid infections was analyzed in a large prospective study that included more than 1,000 medical, demographic, hereditary, and postmortem variables. The disorder was the most frequent cause of death in the study, with an overall perinatal mortality of 6.17 per 1,000 births. The mortality progressively declined after mid-gestation when antimicrobial activity normally appears in the amniotic fluid. A second peak of the fatal infections, after 37 weeks' gestation, was found mainly in the poor and undernourished. Maternal gestational weight gains were suboptimal and the involved neonates had a pattern of growth retardation characteristic of undernutrition. Maternal pregnancy weight gains were positively correlated with the number of prenatal clinic visits. Mother's race, socioeconomic status, age, short stature, and number of prior unsuccessful pregnancies lost their positive association with the fatal infections when mothers made more than nine clinic visits.