[The effects of pregnancy and lactation on bone and mineral metabolism.]

To meet the fetus's calcium demand in the 3rd trimester as much as 300~500 mg/day, intestinal calcium absorption in pregnant women is upregulated, without comparable increase in bone resorption. On the contrary, to provide 210 mg/day of calcium for the neonate, bone resorption by osteoclasts and osteocytes is markedly upregulated in maternal skeleton caused by low estrogen and high PTHrP as a consequence of elevated prolactin production, without any increase in intestinal calcium absorption. Breastfeeding women lose 5~10%of trabecular bone during 3 to 6 months of lactation.