The Effect of Maternal Pre-pregnancy Body Mass Index on Very Low Birth Weight Infants

ABSTRACT

PURPOSE: The pre-pregnancy body mass index (BMI) is associated with adverse neonatal outcomes. However, studies on very low birth weight (VLBW) infants are rare. This study aimed to investigate the effect of maternal pre-pregnancy BMI on VLBW infants. METHODS: This retrospective study evaluated singleton VLBW infants born at the CHA Gangnam Medical Center from 2006 to 2016. The neonates were classified into three groups according to the maternal pre-pregnancy BMI underweight ( < 18.5 kg/m2), normal weight (≥18.5 to < 23 kg/m2), and overweight or obese (≥23 kg/m2). Clinical characteristics and morbidities of mothers and infants were analyzed. RESULTS: A total of 181 infants belonging to underweight (16.6%), normal weight (58.6%), and overweight or obese (24.8%) groups were enrolled. The pre-pregnancy BMI had a significant negative correlation with gestational age (r=−0.198, P=0.001) and a significant positive correlation with the z-score of the birth weight (r=0.078, P=0.001) and body length (r=0.067, P=0.008). The number of extremely preterm infants was significantly higher in the overweight or obese group. The proportion of risk of small for gestational age infants was higher in the underweight group (adjusted odds ratio [OR], 2.958; 95% confidence interval [CI], 1.113 to 7.864), whereas that of infants with severe retinopathy of prematurity was higher in the overweight or obese group (adjusted OR, 9.546; 95% CI, 1.230 to 74.109). CONCLUSION: In our population of VLBW infants, the pre-pregnancy BMI was associated with gestational age, intrauterine growth, and adverse neonatal outcomes. Therefore, proper weight control before pregnancy is important.