[A study on bone density in women during pregnancy and postpartum]

Although 25-30 grams of calcium is transported into the fetus during pregnancy, it is suggested that the maternal bone might be kept at the same density as in non-pregnant women by measuring serum or urinary calcium concentrations and calcium regulating hormones simultaneously (Ohara et al. Folia Endocrinol., 1986). In this study, the influence of pregnancy on the maternal bone was investigated by measuring the degree of bone density in the second metacarpal bone of pregnant or puerperal women in an X-ray picture using a microdensitometer and a computer (Microdensitometry method; MD method, Inoue et al., 1983). Among six indices provided by this method, d (bone marrow width) tended to increase, but MCI (Barnett's metacarpal index) tended to decrease toward late pregnancy. GSmin, GSmax and sigma GS/D were significantly lower in the third trimester of pregnancy than in the second trimester of pregnancy. The densitometric patterns were A in most of the pregnant and puerperal women, but one case with the pattern of AB and two cases with the pattern of B were found in the third trimester of pregnancy. The sum of the scores of the six indices, which were based on the severity of each index, was within 0-3 in pregnant or puerperal women though it tended to increase as pregnancy progressed. From these results, it was confirmed that maternal bone density was maintained within the normal limits throughout pregnancy and postpartum.