Bone Abstracts

Objective: We aimed to investigate associations between early-life vitamin D status, mode of infant milk-feeding and bone outcomes at five years.

Methods: Participants were from the prospective mother-infant SCOPE-BASELINE Birth Cohort Study. Serum 25 hydroxyvitamin D (25(OH)D) concentrations were quantified at 15 weeks gestation, in umbilical cord sera and at two and five years using a gold-standard CDC-accredited LCMS method. Whole-body bone mineral content (BMC), bone area (BA) and areal bone mineral density (aBMD) were assessed in 596 children at five years by dual-energy x-ray absorptiometry (DXA). To adjust for body size, estimated volumetric bone mineral density (vBMD) was calculated by adjusting BMC for BA, weight, and height.

Results: The prevalence of maternal vitamin D deficiency (25(OH)D <30 nmol/l) was 12%, and 41% of mothers were <50 nmol/l at 15 weeks gestation. Forty-three percent of neonates were <30 mol/l, decreasing to 6 and 2% at 2 and 5 years, respectively. Maternal and cord 25(OH)D concentrations were positively correlated (Spearman’s r=0.345, P <0.001). There were no differences in bone outcomes at 5 years across categories of maternal or cord 25(OH)D concentrations (<30, 30–49 and ≥50 nmol/l). By 6 months, 85% of children were receiving infant formula, 95% were receiving complementary foods and 60% were using a vitamin D supplement. Four children (<1%) were exclusively breastfed without supplementation at 6 months. Bone outcomes at 5 years did not differ significantly by type of milk feeding at 6 months. However, among children born to mothers <50 nmol/l, those who were receiving breast milk as their predominant milk source at 6 months (n=27) had lower BMC than children who were mixed- or formula-fed (median (IQR): 406 (375, 441) vs 436 (396, 481) g, P=0.046). These children also had lower aBMD, but differences did not persist for estimated vBMD (P=0.389).

Conclusion: We report a high prevalence of maternal and neonatal vitamin D deficiency that did not track into childhood. Lower maternal vitamin D status, followed by breast milk as the predominant milk source at 6 months was associated with lower BMC, but not size-adjusted BMC at 5 years.

Supported by a grant from the European Commission (ODIN grant 613977).

Disclosure: The authors declared no competing interests.