In-hospital mortality and morbidity among extremely preterm infants in relation to maternal body mass index.

Objective: The objective of this paper is to compare in-hospital survival and survival without major morbidities in extremely preterm infants in relation to maternal body mass index (BMI).

Methods: This retrospective cohort study included extremely preterm infants (gestational age 22-28 weeks). This study was conducted at National Institute of Child Health and Human Development Neonatal Research Network sites. Primary outcome was survival without any major morbidity.

Results: Maternal BMI data were available for 2415 infants. Survival without any major morbidity was not different between groups: 30.8% in the underweight/normal, 28.1% in the overweight, and 28.5% in the obese (P = 0.65). However, survival was lower in the obese group (76.5%) compared with overweight group (83.2%) (P = 0.02). Each unit increase in maternal BMI was associated with decreased odds of infant survival (P < 0.01).

Conclusions: Survival without any major morbidity was not associated with maternal obesity. An increase in maternal prepregnancy BMI was associated with decreased odds of infant survival.