Bone mineral density during pregnancy in women participating in a randomized controlled trial of vitamin D supplementation.
Am J Clin Nutr. 2017 Dec;106(6):1422-1430. doi: 10.3945/ajcn.116.140459. Epub 2017 Oct 18.
Wei W1, Shary JR2, Garrett-Mayer E1, Anderson B3, Forestieri NE2, Hollis BW2, Wagner CL4.
1 Departments of Public Health Sciences and.
2 Pediatrics, Division of Neonatology, and.
3 South Carolina Translational Research Center, Medical U. of South Carolina, Charleston, SC.
4 Pediatrics, Division of Neonatology, and wagnercl at musc.edu.
Background: Little is known about bone mineral density (BMD) during pregnancy. Advances in technology with lower radiation emissions by dual-energy X-ray absorptiometry instruments now permit the safe measurement of BMD during pregnancy.
Objective: We evaluated maternal BMD during pregnancy as a function of vitamin D status in women of diverse racial/ethnic backgrounds.
Design: A total of 301 women who underwent BMD measurements at 12-20 wk of gestation and again at 0-14 wk postpartum were included in this analysis. Women were a subset of subjects who were recruited for a randomized, controlled, double-blind trial of vitamin D supplementation in pregnancy (400, 2000, or 4000 IU/d).
Results: Treatment had no significant effect on changes in BMD that occurred between 12-20 wk of gestation and 0-14 wk postpartum. Similarly, changes in spine and femoral neck bone mineral contents (BMCs) were not significantly different in the treatment groups. In addition, vitamin D inadequacy (serum 25-hydroxyvitamin D concentration, averaged across pregnancy, <50 nmol/L) was not associated with changes in BMD or BMC. There were significant racial/ethnic differences in spine BMD. African Americans lost more spine BMD than did Caucasians (-0.04 ± 0.04 compared with -0.02 ± 0.04 g/cm2; P = 0.033). In addition, baseline obesity was associated with a greater loss of femoral neck BMD. The means ± SDs of femoral neck BMD loss were -0.02 ± 0.05 and 0.0 ± 0.03 g/cm2 for groups with baseline body mass index (BMI; in kg/m2) ≥30 and <30, respectively.
Conclusion: These findings do not support a dose effect of vitamin D supplementation on bone health and suggest that race/ethnicity and BMI play an important role in pregnancy bone health. This trial was registered at clinicaltrials.gov as NCT00292591.
PMID: 29046301 PMCID: PMC5698834 DOI: 10.3945/ajcn.116.140459