Laskey M A, Prentice A, Hanratty L A, Jarjou L M, Dibba B, Beavan S R, Cole T J
MRC Dunn Nutrition Centre, Cambridge, United Kingdom.
Am J Clin Nutr. 1998 Apr;67(4):685-92. doi: 10.1093/ajcn/67.4.685.
Factors influencing the change in bone mineral after 3 mo of lactation were investigated in 47 breast-feeding mothers, 11 formula-feeding mothers, and 22 nonpregnant, nonlactating control subjects. At 6-8 wk postpartum, the breast-feeding group had a mean (+/-SD) calcium intake of 34.8+/-13.2 mmol/d and breast-milk volume, calcium concentration, and calcium output of 0.865+/-0.230 L/d, 7.41+/-1.25 mmol/L, and 6.41+/-2.00 mmol/d, respectively. There was no relation between calcium intake and any breast-milk variable. Dual-energy X-ray absorptiometry of the whole body, spine, hip, and forearm was performed at 0.5 and 3 mo. There were significant decreases in bone mineral content at the spine (3.96%; 95% CI: 4.86%, 3.06%), femoral neck (2.39%; 95% CI: 3.61%, 1.17%), total hip (1.51%; 95% CI: 2.45%, 0.60%), and whole body (0.86%; 95% CI: 1.29%, 0.43%) in breast-feeding mothers but not in formula-feeding mothers or nonpregnant, nonlactating women. These changes were not related to calcium intake, breast-milk calcium concentration, vitamin D-receptor genotype, postpartum weight change, or use of the progesterone-only contraceptive pill. After adjustment for bone area, breast-milk volume and height were identified as significant predictors at the spine, such that greater decreases were associated with taller mothers (P = 0.007) and those with greater breast-milk volume (P = 0.001). This finding suggests that the marked bone mineral changes observed in breast-feeding mothers represented a physiologic response to lactation that was independent of dietary calcium supply.
对47名母乳喂养的母亲、11名配方奶喂养的母亲和22名未怀孕、未哺乳的对照对象进行了研究，以探讨哺乳期3个月后影响骨矿物质变化的因素。产后6 - 8周时，母乳喂养组的平均（±标准差）钙摄入量为34.8±13.2 mmol/d，母乳量、钙浓度和钙输出量分别为0.865±0.230 L/d、7.41±1.25 mmol/L和6.41±2.00 mmol/d。钙摄入量与任何母乳变量之间均无关联。在产后0.5个月和3个月时，对全身、脊柱、髋部和前臂进行了双能X线吸收测定。母乳喂养的母亲脊柱（3.96%；95%可信区间：4.86%，3.06%）、股骨颈（2.39%；95%可信区间：3.61%，1,17%）、全髋（1.51%；95%可信区间：2.45%，0.60%）和全身（0.86%；95%可信区间：1.29%，0.43%）的骨矿物质含量显著下降，而配方奶喂养的母亲或未怀孕、未哺乳的女性则没有这种情况。这些变化与钙摄入量、母乳钙浓度、维生素D受体基因型、产后体重变化或仅使用孕激素避孕药无关。在对骨面积进行调整后，母乳量和身高被确定为脊柱骨矿物质含量变化的重要预测因素，即身高较高的母亲（P = 0.007）和母乳量较多的母亲（P = 0.001）骨矿物质含量下降幅度更大。这一发现表明，母乳喂养母亲中观察到的显著骨矿物质变化代表了对哺乳的一种生理反应，与膳食钙供应无关。
