Infant and maternal bone status are associated in lactating adolescents when calcium intake is low but not following calcium plus vitamin D supplementation

Abstract

The aim of the study was to evaluate the influence of calcium plus vitamin D supplementation during adolescent pregnancy on relationships between infant and maternal bone status during lactation. Adolescent mothers (13–19y) with dietary calcium intake ≈600 mg/d, received daily calcium (600 mg) plus vitamin D3 (200 IU) (n=30) or placebo (n=25) from 26 wk gestation until parturition. Infant and maternal DXA scans were done at 5 wk postpartum. Infant measures included total body bone mineral content (BMC), bone area (BA), and bone mineral density (BMD). In mothers, BMD was measured at total body, lumbar spine (L1–L4), total hip and femoral neck. Associations between infant bone measurements and maternal BMD Z scores were evaluated by partial correlation analysis. In the placebo group, infant BMC and BA were negatively associated with maternal total BMD Z score (r = −0.40; P < 0.05 and r = −0.47; P < 0.02, respectively) while infant BMD was positively associated with mothers’ BMD Z scores at all evaluated regions (r ≥ 0.39; P ≤ 0.05). No associations between infant and maternal bone measurements were observed in the supplemented group. Our results suggest that in adolescent pregnancy the calcium demand for neonate bone accumulation is supplied at the expense of maternal bone mass when calcium intake is low.Financial support: CNPq and FAPERJ (Brazil).