Disparities in vitamin D status of newborn infants from a diverse sociodemographic population in Montreal, Canada

BACKGROUND: Vitamin D status at birth is reliant on maternal-fetal transfer of vitamin D during gestation. OBJECTIVE: To examine vitamin D status of newborn infants in a diverse population and to subsequently identify the modifiable correlates of vitamin D status. DESIGN: In this cross-sectional study, healthy mother-infant dyads (n = 1035) were recruited within 36 h after term delivery (March 2016 to March 2019). Demographic and lifestyle factors were surveyed. Newborn serum 25-hydroxyvitamin D (25OHD) was measured (standardized chemiluminescence immunoassay) and categorized as deficient (serum 25OHD 30 nmol/L) or adequate (≥40 nmol/L). Serum 25OHD was compared among categories of maternal characteristics using ANOVA. Subgroups (use of multivitamins preconception and continued in pregnancy vs. during pregnancy only) were matched (n = 352/group) for maternal factors (ancestry, age, income, education, parity and pre-pregnancy BMI) using propensity scores; logistic regression models were generated for odds of deficiency, or adequacy. RESULTS: Mean serum 25OHD was 45.9 (95% CI: 44.7, 47.0) nmol/L (n = 1035), with 20.8% (95% CI: 18.3, 23.2) deficient and 60.7% (95% CI: 55.2, 66.2) adequate. Deficiency ranged from 14.6% of white infants to 41.7% of black infants. Serum 25OHD was higher (P0.0001) in infants of mothers with higher income, BMI 25 kg/m2, exercise and sun exposure in pregnancy and use of multivitamin preconception. In the matched-subgroup, multivitamin supplementation preconception plus during pregnancy relative to only during pregnancy associated with lower odds for vitamin D deficiency (ORadj: 0.55, 95% CI: 0.36, 0.86) and higher odds for adequate vitamin D status (ORadj: 1.47, 95% CI: 1.04, 2.07). CONCLUSIONS: In this study most newborn infants had adequate vitamin D status yet one-fifth were vitamin D deficient with disparities among population groups. Guidelines for a healthy pregnancy recommend maternal use of multivitamins preconception and continued in pregnancy, emphasis on preconception use may help to achieve adequate neonatal vitamin D status.