Pregnancy and Lactation as Determinants of Bone Mineral Density in Postmenopausal Women

The relation of pregnancy and breast feeding to bone mineral density of the wrist, radius, hip, and spine was examined in a white, upper middle-class, homogeneous sample of 741 postmenopausal women ranging in age from 60 to 89 years. Number of pregnancies ranged from 0 to 14, with a mean of 2.0 pregnancies and 1.5 live births. Almost two thirds of the women who had had a live birth reported breast feeding. Unadjusted comparisons indicated that bone mineral density of the wrist, radius, and hip increased with increasing numbers of pregnancies, and women who had breast-fed had higher bone mineral densities at these sites