A prospective study of bone density and pregnancy after an extended period of lactation with bone loss.

Abstract

To determine if pregnancy after an extended period of lactation curtails the recovery of maternal bone mineral density. Twenty-five women who fully breast-fed their infants for at least 6 months and had a subsequent pregnancy within 18 months of initiating lactation were studied longitudinally. Twenty controls breast-fed similarly, but had no subsequent pregnancy. The women were healthy, well-nourished, and between 20-40 years old. Bone mineral density was measured by dual x-ray energy absorptiometry at the spine and hip. Both cases and controls lost bone mineral density with extended lactation. The case group had a bone mineral density recovery comparable to the controls. Women with the dual calcium demands of extended lactation and a subsequent pregnancy are not at risk for failure of bone recovery to pre-lactation levels.