妊娠・授乳と骨・カルシウム代謝

Calcium Metabolism and Skeletal Changes during Pregnancy and Lactation.

　妊娠・授乳中のカルシウム代謝は大きく変化する。これは胎児・出生児にカルシウムを供給するためである。妊娠中は胎盤を通じて30 gのカルシウムを胎児に蓄積し，授乳期には1日220～340 mgのカルシウムを児に供給する。 　母体のカルシウムは妊娠期には消化管からの吸収を増やすことで，また授乳期には母体骨のカルシウムを供給することで児のカルシウムが賄われ，これら一連は将来の母体の骨粗鬆症の発症には通常寄与しない。 　本稿では妊娠・授乳中の骨・カルシウム代謝，さらにはビタミンDや関連ホルモンに関して述べる。

　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.