Bone mineral density during pregnancy in women participating in a randomized controlled trial of vitamin D supplementation [Vitamins, minerals, and phytochemicals]

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  1. Wei Wei1,
  2. Judith R Shary2,
  3. Elizabeth Garrett-Mayer1,
  4. Betsy Anderson3,
  5. Nina E Forestieri2,
  6. Bruce W Hollis2, and
  7. Carol L Wagner2
  1. 1Departments of Public Health Sciences and
  2. 2Pediatrics, Division of Neonatology, and
  3. 3South Carolina Translational Research Center, Medical University of South Carolina, Charleston, SC
  1. Address correspondence to CLW (e-mail: wagnercl{at}musc.edu).

  • Supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01 HD043921), the NIH (RR01070), and the South Carolina Clinical
    and Translational Research Institute, Medical University of South Carolina (NIH/National Center for Advancing Translational
    Sciences (NCATS) grant UL1 RR029882).

  • Supplemental Tables 1 and 2 are available from the “Online Supporting Material” link in the online posting of the article
    and from the same link in the online table of contents at http://ajcn.nutrition.org.

Abstract

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.

Keywords:

Footnotes

  • Abbreviations used: BMC, bone mineral content; BMD, bone mineral density; DXA, dual-energy X-ray absorptiometry; 25(OH)D,
    25-hydroxyvitamin D.

  • Received June 27, 2016.
  • Accepted September 20, 2017.

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