Risks for premature rupture of amniotic membranes.

The objective of this study was to test the hypothesis that diverse risk variables including infections during the index pregnancy independently increase the risk of preterm premature rupture of amniotic membranes (PROM) and preterm delivery without PROM. A case-control design was used to study women 15-45 years old who had preterm PROM, full-term PROM or preterm without PROM and were singly matched by age race and parity to controls who delivered full-term infants. The odds for preterm PROM was 6.0 times that of controls among women with intra-amniotic infection, 3.7 times among those with urinary tract and 7.6 times among women with gonorrhoea infections after controlling for the effects of exposure to cigarette smoke, having previous preterm and full-term PROM deliveries and antepartum bleeding that independently increased the odds. The odds for preterm births without PROM was 4.8 times that of controls among women with a previous preterm PROM birth, was significantly increased among those exposed to cigarette smoke or having antepartum bleeding, but not among those exposed to chlamydia infection. Even after adjusting for concomitant risk factors, women with preterm PROM births were more likely than their matched controls to have had infections.