Changes in cortical volumetric bone mineral density and thickness, and trabecular thickness in lactating women postpartum.

Context: Lactation is associated with decreased areal bone mineral density (aBMD). Replenishment occurs especially after ceased lactation. Changes in volumetric bone mineral density (vBMD), microstructure, and dimensional parameters are unknown and may clarify the role of lactation for skeletal health. Objective and Main Outcomes: The objective of the study was to test the hypothesis that lactation is associated with changes in aBMD, vBMD, microstructure, and dimensional parameters. Design: At baseline (0.5 mo after delivery) and 4, 12, and 18 months thereafter, bone was assessed using dual-energy x-ray absorptiometry and high-resolution peripheral quantitative computed tomography. Participants and Setting: Eighty-one fair-skinned postpartum women and 21 controls aged 25–40 years were recruited. The completion ratio was 73%. Postpartum women were categorized depending on duration of lactation: 0–3.9, 4–8.9, and 9 months or longer. Results: During the first 4 months, aBMD decreased at several sites (geomet...