Maternal Calciotropic and Bone Biomarker Profiles in Response to a Nutrition+Exercise Intervention in a Randomized Controlled Trial in Pregnancy

Abstract

Background: Pregnancy induces transient bone mass loss. Dairy foods might promote bone health, yet few interventions have been conducted to optimize maternal bone health in the perinatal period.

Objectives: To conduct a Nutrition+Exercise randomized controlled trial (RCT) in pregnant women to assess the impact on maternal bone health by measures of calciotropic and bone biomarkers at the end of pregnancy and in the post-partum period.

Study design: In the Be Healthy in Pregnancy (BHIP) RCT, 203/241 women consented at randomization (12-17 weeks (wk) gestation) to the bone health sub-study and received either usual care or a Nutrition+Exercise intervention that provided an individualized high protein diet (50% as dairy products) and a walking program throughout pregnancy. Maternal characteristics and fasting blood samples were obtained at 12-17 wk and 36-38 wk gestation, and at six months post-partum. Vitamin D status from the BHIP participants was compared to the FAMILY birth cohort participants (assessed at 24-36 wk gestation) to assess changes over a ten-year span. The response of the calciotropic and bone biomarkers to the RCT intervention was assessed at the end of pregnancy and in the post-partum period.

Results: Adequate vitamin D status in pregnancy was observed in 322 participants from the FAMILY and 191 from the BHIP study, impacted by season and supplement intake. For participants in the BHIP study, serum 1,25-dihydroxyvitamin D concentrations increased throughout pregnancy and were not associated with serum 25(OH)D. Participants from the intervention group had lower serum bone resorption marker CTX compared to control group, which was reflected in cord serum. No differences were observed with other bone biomarkers at the end of pregnancy or in the post-partum period.

Conclusion: Higher protein and calcium intake compared to the control group during pregnancy minimized bone resorption, thus protecting maternal bone health in the perinatal period.