PREVIOUS PREGNANCY OUTCOMES AND SUBSEQUENT RISK OF PRETERM RUPTURE OFAMNIOTIC SAC MEMBRANES

Objective To test the hypothesis that previous unfavourable pregnancy outcomes increase the risk for premature birth, with (PP) or without ( PTB) premature rupture of the amniotic sac (PROM) at the index pregnan cy and that multiple undesirable outcomes increase risk. Design Case c ontrol study. Setting Two university hospitals. Subjects Four hundred sixty-three women aged 15 to 45 years who were delivered preterm PROM, full term PROM and preterm without PROM matched with 463 women who de livered full term. All women included in the study had at least one pr evious pregnancy. Outcome measures Odds ratio of previous adverse preg nancy outcome among index cases. Results Compared with controls, PP ca ses had odds ratios of 95 for previous preterm birth, 186 for abortion and prematurity and 158 for fetal loss, abortion/prematurity after co ntrolling for confounding variables. Compared with controls, PTB cases had an odds ratio of 96.5 for previous preterm delivery, 84 for abort ion and prematurity, and 320 for fetal loss/abortion and prematurity a fter controlling for confounding variables. Conclusions Previous prete rm delivery, abortion and prematurity and fetal loss/abortion and prem aturity all increase risk for subsequent preterm birth with or without PROM.