Outcome of extremely preterm infants after iatrogenic or spontaneous birth.

INTRODUCTION: The risks of preterm birth are known. We investigated the perinatal and infant mortality and morbidity after iatrogenic or spontaneous onset of extremely preterm birth.

MATERIAL AND METHODS: The present study used data from the population-based EXPRESS study comprising all infants delivered before 27+0 gestational weeks in Sweden between 2004 and 2007. All fetuses alive at admission and with known mode of onset of delivery were included (682 live-born infants; 65 intrapartum deaths). Four multivariate regression models were applied with adjustments for gestational age, fetal gender, multiple pregnancy, and birthweight.

RESULTS: After adjustment for gestational age, no significant differences were found between iatrogenic and spontaneous onsets of birth regarding intrapartum death, early neonatal death (0-6 d), or death within 364 days. In the group with iatrogenic onset of delivery, there was an increased risk for severe morbidity (odds ratio [OR] 1.86, 95% confidence interval [95% CI] 1.15-3.02), severe bronchopulmonary dysplasia (OR 1.90, 95% CI 1.10-3.26), and retinopathy of prematurity (OR 1.99, 95% CI 1.21-3.27) after adjustment for gestational age, fetal gender, and multiple pregnancy. After additional adjustment for weight z-scores at 36 gestational weeks, the associations were not significant. Within the group with spontaneous onset of delivery, fetuses with preterm prelabor rupture of membranes had increased mortality risk.

CONCLUSIONS: No evidence was found for mode of onset of delivery (iatrogenic vs spontaneous) having an impact on neonatal or infant mortality or morbidity in extremely preterm infants. Instead, gestational age and growth deviation at birth seem to be associated with the outcome.