Concurrent calcium and vitamin D supplementation during pregnancy increases bone density in adolescent mothers

Adolescent mothers with low calcium intakes should take calcium plus vitamin D supplementation during pregnancy because it is likely to result in higher lumbar spine bone mass and a reduced rate of femoral neck bone loss during lactation.

The calcium demand increases during pregnancy and lactation periods to transfer adequate amounts of calcium to the growing fetal skeleton and for breast-milk production. In young mothers with low calcium intake, maternal bone mass could be negatively affected. Some studies have indicated that greater bone losses were seen in adolescent mothers from early pregnancy to 6 week postpartum and from 2 to 16 week lactation, in comparison to adult mothers. In lactating adolescent mothers, the total bone mineral content and the total bone mineral density was reduced. Lumbar spine scores after delivery were linked with calcium intake during the third trimester of pregnancy. However, there have been no studies to test if an increase in calcium intake by using supplements during pregnancy could be protective against loss of bone mass during lactation in adolescent mothers. Furthermore, because vitamin D is important for calcium absorption and to boost bone metabolism, vitamin D must be administered concurrently with calcium supplements. Therefore, this study was conducted to investigate the influence of calcium plus vitamin D supplementation during the last trimester of pregnancy on bone mass and bone and calcium related hormones during lactation, in Brazilian adolescent mothers who habitually consume low-calcium diets.

Pregnant adolescents, aged 14-19y, were chosen randomly to receive daily calcium (600 mg) plus vitamin D3 (200 IU) or a placebo (n = 26) from 26 weeks of pregnancy until parturition. The bone mineral content (BMC), bone area (BA) and bone mineral density (BMD) at the total body, lumbar spine and hip were evaluated at 5 and 20 weeks postpartum. Serum hormones and 25-hydroxyvitamin D [25(OH)D] were measured. At the beginning of the study, mean chronologic age and time elapsed since the onset of menarche was 17.0 and 5.3 y, respectively. The body mass index was within the normal range. There were no significant differences in body weight and height between the 2 groups at 5 and 20 week postpartum. The mean serum 25(OH)D concentration was 59 nmol/L at baseline. When compared 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. Supplemented mothers had higher lumbar spine BA (P = 0.002) and lumbar spine BMC (P = 0.08) than did mothers who consumed the placebo at 5 week postpartum. Differences between groups were more evident at 20 week postpartum, with higher lumbar spine BMC, BA and BMD in the supplemented group (P ≤ 0.008).

In conclusion, through the findings of this study, it is highly recommended that adolescent mothers with low calcium intakes should take calcium plus vitamin D supplements during pregnancy because it is likely to result in higher lumbar spine bone mass and a reduced rate of femoral neck bone loss during lactation.

References

  1. Diogenes, M.E., et al., Effect of calcium plus vitamin D supplementation during pregnancy in Brazilian adolescent mothers: a randomized, placebo-controlled trial. Am J Clin Nutr, 2013. 98(1): p. 82-91.