Changes of bone mineral content during pregnancy and lactation

In order to study changes in the calcium depots of the body during pregnancy and lactation, bone mineral deteminations were performed on fourteen pregnant women and eighteen mothers post partum by X-ray spectrophotomeyry. Pregnant women exhibited a loss in trabecular bone but not in cortical bone when measured once during late first or early second trimester and again one week post partum. Lactating women who nursed less than three months lost mineral during the first three months and than regained it while those who nursed for longer than three months had no losses during six months of study.