Influence of chorioamnionitis on developmental outcome in very low birth weight infants

Objective: To determine the effect of exposure to chorioamnionitis on devel opmental outcome in very low birth weight (VLBW) infants. Methods: Five hundred four maternal charts (97% of all VLBW infants deliver ed from 1990 to 1994) were reviewed. A historical cohort study of the 330 i nfants delivered secondary to preterm premature rupture of membranes or pre term labor was performed. Case subjects (71) were delivered of mothers with chorioamnionitis by clinical criteria; control subjects (259) were deliver ed of mothers without chorioamnionitis. Bayley index scores at 7 months' co rrected age and special care nursery outcomes were compared. One hundred se venty-three subjects were necessary to reject the two-sided null hypothesis with 80% power with a difference in mean Bayley index scores of at least 8 . Results: Neonatal sepsis (8.5% compared with 1.9%; odds ratio [OR] = 4.7, 9 5% confidence interval [CI] 1.4, 15.9, P = .015) and a low 5-minute Apgar ( 72% compared with 55%; DR = 2.1, CI 1.2, 3.8, P = .012) occurred more frequ ently in the chorioamnionitis group. One hundred eighty-seven (68%) of 273 surviving neonates had follow-up. Cases and controls were similar in mean B ayley mental developmental index (91.2 compared with 91.8, P = .84), Bayley psychomotor developmental index (89.8 compared with 89.1, P = .82), and nu mber of infants developmentally delayed. Duration of exposure to chorioamni onitis did not affect neonatal outcome. Conclusion: Despite higher rates of sepsis and low Apgar scores, no differe nce in outcome at 7 months of corrected age was detected in VLBW infants ex posed to chorioamnionitis. Contemporary neonatal management may reduce the adverse effects of this exposure. (C) 1999 by The American College of Obste tricians and Gynecologists.