Kalkwarf H J, Specker B L
Division of Neonatology, Children's Hospital Medical Center, Cincinnati, Ohio, USA.
Obstet Gynecol. 1995 Jul;86(1):26-32. doi: 10.1016/0029-7844(95)00083-4.
To test the hypothesis that bone mineral content (BMC) and density (BMD) are lost during lactation and regained within 6 months after weaning.
Two cohorts of women, defined by time postpartum, were enrolled into the study; each cohort was followed for 6 months. Women in the lactation cohort (65 lactating women and 48 nonlactating postpartum controls) were enrolled at 2 weeks postpartum. Women in the weaning cohort (40 lactating and 43 nonlactating postpartum controls) were enrolled at 4-6 months postpartum. Lactating women enrolled in the weaning cohort had been fully breast-feeding at enrollment and weaned within 2 months of enrollment. Bone mineral content of the total body and BMD of the lumbar spine and distal radius were measured by dual-energy x-ray absorptiometry.
Lactating women lost significantly more bone in the total body (-2.8 versus -1.7%) and lumbar spine (-3.9 versus 1.5%) than did nonlactating women during the first 6 months postpartum. There was no effect of lactation on bone changes at the distal radius. After weaning, lactating women gained significantly more bone in the lumbar spine than did nonlactating women (5.5 versus 1.8%). Earlier resumption of menses was associated with a smaller loss of bone during lactation and a greater increase of bone after weaning.
Women lose bone during lactation but gain bone after weaning. Thus, lactation may not result in net bone loss.
验证骨矿物质含量（BMC）和骨密度（BMD）在哺乳期会流失且在断奶后6个月内会恢复的假设。
根据产后时间定义了两组女性纳入研究；每组随访6个月。哺乳期组（65名哺乳期女性和48名非哺乳期产后对照）在产后2周纳入。断奶组（40名哺乳期和43名非哺乳期产后对照）在产后4 - 6个月纳入。纳入断奶组的哺乳期女性在入组时完全母乳喂养且在入组后2个月内断奶。通过双能X线吸收法测量全身骨矿物质含量以及腰椎和桡骨远端的骨密度。
在产后的前6个月，哺乳期女性全身（-2.8%对-1.7%）和腰椎（-3.9%对1.5%）的骨量流失明显多于非哺乳期女性。哺乳期对桡骨远端的骨变化没有影响。断奶后，哺乳期女性腰椎的骨量增加明显多于非哺乳期女性（5.5%对1.8%）。月经较早恢复与哺乳期较小的骨量流失以及断奶后较大的骨量增加相关。
女性在哺乳期会流失骨量，但断奶后会增加骨量。因此，哺乳期可能不会导致净骨量流失。
