[Changes in bone mineral content and bone metabolism during pregnancy and puerperium]

In order to clarify the bone metabolism of women during both pregnancy and puerperium, we studied the changes in bone mineral content and bone biochemical parameters. Bone mineral content was measured by ultrasound bone densitometry, and serum calcium (Ca), ionized calcium (i-Ca), intact parathyroid hormone (i-PTH), intact osteocalcine (i-OC), urinary pyridinoline (Pyr) and deoxypyridinoline (D-Pyr) were measured concomitantly. 1. In the 3rd trimester bone stiffness was decreased (p < 0.05) compared the 1st and 2nd trimesters, but was slightly increased in the puerperal group. 2. Serum i-OC was decreased during pregnancy but significantly increased (p < 0.01) in the puerperium. The Pyr/Creatinine (Cre) and D-Pyr/Cre ratios were both increased in pregnant and puerperal women. 3. Serum Ca, i-Ca and i-PTH were within the normal range during pregnancy and the puerperium. These results suggest that in the 2nd and 3rd trimesters bone resorption would be increased, and in the puerperium bone formation would be increased. In pregnant and puerperal women serum Ca, i-Ca and i-PTH are within the normal range, but the turnover rate for Ca metabolism would be relatively increased.