Indicated versus spontaneous preterm delivery: An evaluation of neonatal morbidity among infants weighing <= 1000 grams at birth

OBJECTIVE: The aim of the study was to determine whether infants weighing l ess than or equal to 1000 g after birth who are born to women who undergo i ndicated preterm delivery have different neonatal outcomes than do those bo rn as a result of either spontaneous preterm labor or preterm premature rup ture of membranes. STUDY DESIGN: in a I-year observational study (1992-1993) the National Inst itute of Child Health and Human Development Maternal-Fetal Medicine Units N etwork collected outcome data for 799 infants whose birth weights were less than or equal to 1000 g. Only singleton infants with gestational age >20 w eeks who were not produced as the result of an induced abortion were includ ed. Our analysis was further limited to infants without major congenital an omalies who survived >2 days, were deemed potentially viable by the obstetr ician, and would have undergone a cesarean delivery for fetal indications ( N = 411). The primary reason for delivery was categorized as indicated deli very, spontaneous preterm labor, or spontaneous preterm premature rupture o f membranes. Selected neonatal outcomes were evaluated among infants born t o women in each of these groups. Logistic regression analyses were used to control for the effects of other potentially confounding variables. RESULTS: A total of 156 of the 411 infants were born to women who underwent an indicated preterm delivery, whereas 160 were born after spontaneous pre term labor and 95 were delivered after preterm premature rupture of membran es. Univariate analyses revealed significantly lower incidences of grade II I or IV intraventricular hemorrhage, grade III or IV retinopathy of prematu rity, and seizure activity among infants born in an indicated preterm deliv ery than among those born after spontaneous preterm labor or preterm premat ure rupture of membranes. However, infants of women who underwent indicated preterm delivery had a more advanced mean gestational age at birth than di d those born after spontaneous preterm labor or preterm premature rupture o f membranes (28 +/- 2 weeks, 26 +/- 2 weeks, and 26 +/- I weeks. respective ly, P < .001). Multiple logistic regression analysis was therefore used to control for the disparity in gestational age. Multivariate analyses did not confirm the apparent improvement in neonatal outcome in the indicated deli very group. CONCLUSION: In this population of infants weighing less than or equal to 10 00 g, selected neonatal outcomes did not differ according to birth by indic ated preterm delivery, spontaneous preterm labor, or preterm premature rupt ure of membranes.