PRETERM PRELABOR AMNIORRHEXIS - OUTCOME OF LIVE BIRTHS

Objective: To investigate the risk of postnatal death in pregnancies w ith preterm prelabor amniorrhexis in relation to gestational age at bo th amniorrhexis and delivery. Methods: In 172 singleton pregnancies wi th preterm prelabor amniorrhexis resulting in Live births, postnatal s urvival and cause of death were examined in relation to gestational ag e at both amniorrhexis and delivery. In 108 of the patients, the amnio tic fluid index (AFI) and fetal breathing movements were determined, a nd in 98, the internal thoracic circumference and cardiothoracic ratio were also measured. The value of these indices in the prediction of p ulmonary hypoplasia was examined. Results: There were 30 (17%) deaths, 18 of which were due to pulmonary hypoplasia and 12 to prematurity-re lated complications. Survival was related to both gestational age at a mniorrhexis (50% for amniorrhexis before 20 week;;' gestation and 98% when amniorrhexis occurred after 25 weeks) and gestational age at deli very (57% for those born at 24-28 weeks' gestation and 96% for those b orn after 32 weeks). Pulmonary hypoplasia was also related to both ges tational age at amniorrhexis (causing 92% of deaths in the group with amniorrhexis at less than 20 weeks' gestation but none of those with a mniorrhexis after 23 weeks) and gestational age at delivery (causing 5 0% of deaths in the group delivered at 24-28 weeks' gestation and 87% of deaths in infants delivered after 28 weeks). Fetal breathing moveme nts were present in 33 and 63% of cases with and without pulmonary hyp oplasia, respectively. The corresponding values for internal thoracic circumference below the 2.5 percentile were 33 and 9%, respectively. T here were no significant differences in the AFI or cardiothoracic rati o between the cases with and without pulmonary hypoplasia. Multivariat e analysis demonstrated that the only characteristic that contributed significantly in distinguishing between cases with and without pulmona ry hypoplasia was gestational age at amniorrhexis. Conclusion: In preg nancies with preterm prelabor amniorrhexis, postnatal survival is rela ted to both gestational age at amniorrhexis and gestational age at del ivery. Prediction of pulmonary hypoplasia is primarily dependent on ge stational age at amniorrhexis.