Effect of Calcium Plus Vitamin D Supplementation on Adolescent Mother and Infant Bone Health

Calcium Plus Vitamin D Supplementation During Pregnancy of Adolescent Mothers: Effects on Maternal and Infant Bone Mass, Calcium and Bone Metabolism and Breast Milk Composition

Pregnancy and lactation are periods of high calcium requirement. Inadequate maternal calcium intake and vitamin D insufficiency may adversely affect fetal and neonatal growth and maternal bone mass particularly in adolescent mothers. The investigators propose to evaluate the influence of calcium plus vitamin D supplementation during pregnancy on bone mass of lactating adolescent mothers with habitually low calcium and vitamin D, on fetal growth and neonate bone mass. Mothers are randomly assigned to receive daily calcium (600 mg) plus vitamin D3 (200 IU) supplement or placebo from mid gestation until parturition. Fetal growth parameters are assessed by standard ultrasound techniques at mid and late gestation. Maternal bone mass is assessed by dual energy x-ray absorptiometry (DXA) at 2 and 5 months postpartum and 6 months after weaning. Infant bone mass is assessed by DXA at 2 months postpartum.

Inclusion Criteria:

• 13-19 y old
• between 23 and 29 wk of gestation
• primiparous
• carrying single fetus
• intending to exclusively or predominantly breastfeed

Exclusion Criteria:

• chronic health problems
• smokers
• users of nutritional supplements, except iron supplements provided during standard prenatal care