MATERNAL VITAMIN D STATUS DURING PREGNANCY AS A PREDICTOR OF OFFSPRING BONE MASS AT THREE YEARS OF AGE

Abstract

<p>Emerging evidence indicates that in utero exposure to vitamin D metabolites may influence fetal and neonatal bone development. Bone accretion in prenatal and early postnatal life may impact peak bone mass achieved in early adolescence; and peak bone mass is a well-established predictor of osteoporosis risk in later life. <strong>Hypothesis</strong>: We hypothesized that offspring of mothers with higher serum vitamin D status during pregnancy will have higher whole body BMC z-score and bone size at 3 years of age, after adjustment for confounders. <strong>Methods</strong>: In a prospective, longitudinal study, 372 mothers with singleton birth were recruited during pregnancy, and maternal blood samples were obtained during the third trimester. Child bone outcome measures at 3 years of age included: whole body BMC, femoral and humeral lengths by DXA. We controlled for other relevant factors such as maternal nutrition, pre-pregnancy BMI, physical activity during pregnancy, maternal BMD, as well as the child’s nutrition at 6 months and 3 years, and the child’s physical activity. <strong>Results & Discussion</strong>: Maternal vitamin D status during pregnancy did not predict whole body BMC z-score of the child at 3 years of age. Over 92% of Canadian women in our sample were vitamin D sufficient with mean intakes of 435 IU/day from food and supplements and mean serum 25OHD of 111.2 nM. Further, data indicate a potential negative effect on offspring bone size at maternal serum 25OHD concentrations that exceed the upper limit suggested by the most recent DRI report (>125 nM), at which adverse health effects may occur. Our findings may differ from previous studies in the United Kingdom, India and Finland that found a positive relationship between maternal vitamin D status and child bone outcomes due to the high frequency of our mothers that had optimal vitamin D status. In addition, we adjusted for most of the key covariates that were not adjusted for in previous studies, which may contribute to the different findings compared to previous investigations.</p>