The association between maternal body mass index and severity of neonatal illness in very low birth weight infants

Objective. To determine the effect of maternal body mass index (BMI) and pregnancy weight gain on neonatal illness severity in very low birth weight infants. Methods. Cohort study of infants with birth weight less than 1500 g at a level 3 Neonatal Intensive Care Unit from July 2003 to July 2005, n = 301. The main outcome included neonatal illness severity, as measured by the Score for Neonatal Acute Physiology (SNAP). SNAP was investigated in relationship to maternal BMI and pregnancy weight gain. Statistical analysis included Pearson correlation, ANOVA and multivariable linear regression. Results. At delivery and pre-pregnancy, 49 and 54% of mothers were overweight, respectively. Black mothers were more likely to be overweight with less pregnancy weight gain compared with white mothers. After controlling for confounding variables, maternal pre-pregnancy BMI, pregnancy BMI and weight gain were not associated with neonatal illness. Conclusions. In our population of very low birth weight infants, maternal BMI was not associated with neonatal illness severity. Black mothers had higher pre-pregnancy BMI and less weight gain than white mothers. The significance of these differences needs further exploration.