ASSOCIATION OF MATERNAL SERUM VITAMIN D LEVELS AND FETAL GROWTH AND NEONATE BODY COMPOSITION

Abstract

Background: Maternal serum 25−hydroxyvitamin D (25(OH)D) deficiency in pregnancy has been associated with decreased infant birth weight, although research has not been consistent. No research is available investigating the effects of serum 25(OH)D on estimated fetal weight (EFW). Only one study has been published relating infant body composition to maternal serum vitamin D status. Purpose: The purpose of this study was to further investigate the relationship between maternal serum 25(OH)D and fetal growth and neonate body composition. Methods: Sixty−three pregnant women had serum 25(OH)D analyzed late in pregnancy. Percent fat (%fat), fat mass (FM), and fat free mass (FFM) of the offspring were analyzed using air displacement plethysmography within 72 hours of life. Multiple linear regression was used to assess the relationship between maternal 25(OH)D and infant body composition. Covariates considered included pre-pregnancy body mass index (BMI), total gestational weight gain (GWG), infant gender, and infant age at test. Fifty−six and 31 participants had data estimating fetal weight in early and late gestation, respectively. The relationship between maternal serum 25(OH)D and EFW was assessed using multiple linear regression. Covariates considered in this analysis were pre-pregnancy BMI, GWG up to sonogram measurement, gestational age (GA) at measurement, and infant gender. Results: The mean serum 25(OH)D of the sample was 52.6 nmol/L, with 50.7% below 50nmol/L, which is defined as deficient by the Endocrine Society. Across classification groups those classified as serum 25(OH)D deficient had significantly higher pre-pregnancy BMIs, than those that were classified as having adequate or insufficient serum 25(OH)D. Gestational age at birth was the only predictor of infant birth weight (β= 171.050, p= 0.005). Infant %fat and FM were both predicted by age at test alone (β= 1.61, p= 0.037; β= 87.45, p= 0.004). FFM was predicted by infant age at test (β= 158.24, p= 0.001), gender (β= − 197.34, p= 0.004), and GA at birth (β= 194.37, pp= 0.006) and GA at measurement (β= 65.65, ppConclusion: Maternal serum 25(OH)D was not a predictor of birth weight, infant %fat, FM, FFM, or EFW in early or late pregnancy.