Background: Pregnancy and lactation in adolescents with habitually low calcium intake may adversely affect maternal bone mass. Objective: We investigated the effect of calcium plus vitamin D supplementation during pregnancy on bone mass during lactation in Brazilian adolescent mothers with low-calcium diets (w600 mg/d). Design: Pregnant adolescents (14-19 y) randomly received daily calcium (600 mg) plus vitamin D 3 (200 IU) (n = 30) or a placebo (n = 26) from 26 wk of pregnancy (baseline) until parturition. The bone mineral content (BMC), bone area (BA), and bone mineral density (BMD) at the total body, lumbar spine, and hip (total and femoral neck) were evaluated by using dual-energy X-ray absorptiometry at 5 and 20 wk postpartum. Serum hormones and 25-hydroxyvitamin D [25(OH)D] were measured. Group comparisons were adjusted for significant covariates. Results: The mean serum 25(OH)D concentration was 59 nmol/L at baseline. In comparison with the placebo, 25(OH)D tended to be 14-15 nmol/L higher postpartum in the supplemented group (P = 0.08). Total body and hip BMC and BMD decreased over time (P # 0.005) in both groups with a group 3 time interaction at the femoral neck (P , 0.04). Supplemented mothers had higher lumbar spine BA (6.7%; P = 0.002) and lumbar spine BMC (7.9%, P = 0.08) than did mothers who consumed the placebo at 5 wk postpartum. At 20 wk postpartum, differences between groups were more evident, with higher lumbar spine BMC (13.9%), lumbar spine BA (6.2%), and lumbar spine BMD (10.6%) in the supplemented group (P # 0.008). Conclusions: Calcium plus vitamin D supplementation during pregnancy of adolescents with low calcium intake results in higher lumbar spine bone mass and a reduced rate of femoral neck bone loss during lactation. Additional studies are required to determine whether bone effects are temporary or long-lasting. This trial was registered at clinicaltrials.gov as NCT01732328.Am J Clin Nutr 2013;98:82-91.

Calcium and vitamin D supplementation of the adolescents studied resulted in higher fetal body weight at 36 wk of gestation and had no effect on infant bone mass at 5 wk postpartum. Because correlations between maternal and infant bone mass were evident only in the placebo group, infant bone mass appeared to be more dependent on maternal skeletal mass when calcium intake was low. This trial was registered at clinicaltrials.gov as NCT01732328.

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).