Controversy exists as to whether a separate entity of pregnancy-induced osteoporosis exists or whether pregnancy is an incidental or precipitating factor in persons who already have osteoporosis. The syndrome is considered rare with about 80 cases documented in the literature. The women who are affected often present with vertebral fractures in the third trimester or shortly after delivery. Densitometry has demonstrated markedly low bone density in both the spine and proximal femur (81). Five cases of postpregnancy osteoporosis have been reported by Yamamoto et al. (82). These women ranged in age from 24 to 37 years. Of the five women, four were diagnosed after their first pregnancy. The fifth was diagnosed after her second pregnancy. All of the women presented with back pain and vertebral compression fractures, most within 1 month of delivery. BMD measurements were made at the 33% radial site with SPA (Norland-Cameron) and at the spine by either QCT or DXA (Hologic QDR-1000). Measurements were made at various times in the evaluation and management of these patients. BMD at the 33% radial site was not decreased in these women when compared to a reference population. BMD at the spine by either QCT or DXA revealed values lower than expected for the population.
The effect of pregnancy and lactation on bone density was studied by Karlsson et al. (83). DXA measurements of the PA lumbar spine, total body, and proximal femur were performed using a Lunar DPX-L. Seventy-three women who were 5 or fewer days postpartum were compared to 55 age-matched controls. Lumbar spine BMD was 7.6% lower and total body BMD was 3.9% lower in the postpartum women than in the controls. Of the postpartum women, 65 were followed to determine the effects of lactation on BMD. Those women who did not breastfeed showed no changed in bone density. Femoral neck bone density decreased by an average of 2% in the first 5 months after delivery in those women who breastfed for 1 to 6 months with no additional bone loss being seen between months 5 and 12 postdelivery. Women who breastfed for more than 6 months had an 8.5% decline in BMD at Ward's area and a 4.1% decline in BMD at the lumbar spine at 5 months postpartum. No additional loss was seen at 12 months postpartum. Femoral neck BMD decline by 4% in this group at 12 months postpartum. The authors also noted that there appeared to be no difference in BMD between women with two or fewer pregnancies compared to women with four or more pregnancies.
More et al. (84) also studied the effects of pregnancy and lactation in 38 healthy Caucasian women with an average age of 26 years. Bone density was measured at the PA lumbar spine, 33% and ultradistal radius with DXA (Lunar DPX-L). Measurements were made within 3 months prior to conception, delivery, and at 6 and 12 months postpartum. Bone density was measured at the radius only at 22 to 24 weeks of gestation. During pregnancy, the average weight gain was 27.6 lb. The women were divided into three groups based on the duration of lactation. The duration of lactation in group 1 was 0 to 1 month. In group 2, the duration was 1 to 6 months and in group 3, 6 to 12 months. For the entire group, PA lumbar spine bone density decreased significantly by 2.1% during pregnancy. Bone density also decreased significantly during pregnancy at the 33% and ultradistal radius by 3.8% at each site. In group 1, there was no difference in PA lumbar spine BMD and 33% radial BMD seen at delivery and at the 6-month and 12-month postpartum visits. Bone density at the ultradistal radial site increased significantly by 5% between delivery and the 12-month postpartum visit in group 1. In group 2, bone density at the PA lumbar spine decreased 4.9% between delivery and the 6-month postpartum visit and then increased 2.3% between the 6-month and 12-month postpartum visits. At 12 months postpartum, the PA lumbar spine bone density was still 2.6% lower than at delivery in group 2. No significant change was noted at the 33% radial site postpartum in group 2 but there was a significant 4.3% decline between delivery and the 6-month postpartum visit at the ultradistal radial site. Between the 6-month and 12-month postpartum visit, the ultradistal radial BMD increased by 3.1%. In group 3, with the longest duration of lactation, PA lumbar spine bone density decreased by 7.4% in the first 6 months postpartum and continued to decreased during the second 6 months postpartum. Once again, there was no significant change seen at the 33% radial site postpartum in this group, but there was a significant 4.9% loss seen at the ultradistal radius in the first 6 months postpartum that was followed by a 3% gain in the second 6 months postpartum. The authors proposed that during pregnancy fetal skeleton calcium needs were derived from maternal cortical and trabecular sites but primarily trabecular sites met calcium needs during lactation.
Was this article helpful?