Changes in biochemical bone markers during pregnancy and puerperium

To elucidate the changes in bone turnover during pregnancy and puerperium, we measured serially the levels of serum osteocalcin and urine deoxypyridin oline (Dpy) as markers of bone formation and bone resorption, respectively, in 22 healthy women with normal pregnancy. Nineteen non-pregnant women ser ved as control. The Dpy levels increased significantly at 16 weeks of pregn ancy and remained elevated thereafter. The levels of osteocalcin, however, were significantly decreased at 16 weeks of pregnancy and elevated later at 6 weeks postpartum. Bone turnover ratio (Dpy/osteocalcin) continued to ris e during pregnancy, but returned to control levels 6 weeks after delivery. Dpy levels and bone turnover ratio during puerperium tended to be higher in 17 breast-feeding women than those of 5 exclusive bottle-feeders. In concl usion, bone resorption begins to increase from the second trimester of preg nancy and calcium release from bone tissue might play a major role in calci um homeostasis during the whole period of pregnancy as well as during lacta tion.