Maternal Serum 25-Hydroxyvitamin D Concentrations during Pregnancy and Infant Birthweight for Gestational Age: A Three-Cohort Study ; Paediatr Perinat Epidemiol

Background ; In response to inconsistent findings, we investigated associations between maternal serum 25-hydroxyvitamin D (25(OH)D) concentrations and infant birthweight for gestational age (BW/GA), including potential effect modification by maternal race/ethnicity and infant sex. ; Methods ; Data from 2,558 pregnant women were combined in a nested case-control study (preterm and term) sampled from three cohorts: the Omega study, the Pregnancy, Infection and Nutrition study, and the Pregnancy Outcomes and Community Health study. Maternal 25(OH)D concentrations were sampled at 4 to 29 weeks’ gestation (80% 14–26 weeks). BW/GA was modeled as sex-and gestational age-specific birthweight z-scores. General linear regression models (adjusting for age, education, parity, pre-pregnancy body mass index, season at blood draw, and smoking) assessed 25(OH)D concentrations in relation to BW/GA. ; Results ; Among non-Hispanic Black women, the positive association between 25(OH)D concentrations and BW/GA was of similar magnitude in pregnancies with female or male infants (beta (β)=0.015, standard error (SE)=0.007, P=0.025; β=0.018, SE=0.006, P=0.003, respectively). Among non-Hispanic White women, 25(OH)D-BW/GA association was observed only with male infants and the effect size was lower (β=0.008, SE=0.003, P=0.02). ; Conclusions ; Maternal serum concentrations of 25(OH)D in early and mid-pregnancy were positively associated with BW/GA among non-Hispanic Black male and female infants and non-Hispanic White male infants. Effect modification by race/ethnicity may be due, in part, to overall lower concentrations of 25(OH)D in non-Hispanic Blacks. Reasons for effect modification by infant sex remain unclear. ; R01 HD34543/HD/NICHD NIH HHS/United States ; M01 RR000046/RR/NCRR NIH HHS/United States ; R01 HD039373/HD/NICHD NIH HHS/United States ; HD28684A/HD/NICHD NIH HHS/United States ; R01 HD034543/HD/NICHD NIH HHS/United States ; RR0046/RR/NCRR NIH HHS/United States ; HD39373/HD/NICHD NIH HHS/United States ; R01 ...