Preterm birth, premature rupture of membranes, and cervical incompetence.

Preterm birth, due to shortened gestation with birth prior to 37 completed weeks gestation, accounts for up to 75% of perinatal morbidity and mortality in the United States. Much basic and clinical research is focused on understanding the epidemiology, pathobiology, and possible means to treat or prevent preterm labor, premature rupture of membranes, and cervical factors leading to preterm birth. Recent key areas of progress in these problems are selectively reviewed, emphasizing aspects that are considered most important for further progress.