[Calcium Metabolism and Skeletal Changes during Pregnancy and Lactation.]

Calcium metabolism changes dramatically during pregnancy and lactation because offspring needs a supply of calcium. Approximately 30g of calcium, which passes through the placenta, is accumulated in a fetus during pregnancy mostly in the third trimester, and 220-340mg/day of calcium is supplied via breast milk during lactation. However, there are elaborate mechanisms to maintain maternal calcium homeostasis, which differs during pregnancy and lactation. Extra required calcium supply to the offspring in neither pregnancy nor breastfeeding normally do not cause any adverse consequences to the maternal skeleton even if any oral intake of calcium or vitamin D are increased. This article reviews the adaptation in calcium kinetics during pregnancy and lactation. Vitamin D, calciotropic hormones, and bone metabolism are also reviewed.