Journal Article

The effect of an exercise program in pregnancy on vitamin D status among healthy, pregnant Norwegian women: a randomized controlled trial

Romundstad, Pål R., Mørkved, Siv, Salvesen, Kjell Åsmund, Mosti, Mats Peder, Stunes, Astrid Kamilla, Helvik, Anne-Sofie, Thorsby, Per Medbøe, Syversen, Unni, Gustafsson, Miriam K., Stafne, Signe Nilssen

2019

Overview

Background Vitamin D insufficiency is common in pregnant women worldwide. Regular prenatal exercise is considered beneficial for maternal and fetal health. There is a knowledge gap regarding the impact of prenatal exercise on maternal vitamin D levels. The objective of this study was to investigate whether a prenatal exercise program influenced serum levels of total, free and bioavailable 25-hydroxyvitamin D (25(OH)D) and related parameters. This is a post hoc analysis of a randomized controlled trial with gestational diabetes as the primary outcome. Methods Healthy, pregnant women from two Norwegian cities (Trondheim and Stavanger) were randomly assigned to a 12-week moderate - intensity exercise program (Borg perceived rating scale 13–14) or standard prenatal care. The intervention group ( n  = 429) underwent exercise at least three times weekly; one supervised group training and two home based sessions. The controls ( n  = 426) received standard prenatal care, and exercising was not denied. Training diaries and group training was used to promote compliance and evaluate adherence. Serum levels of 25(OH)D, parathyroid hormone, calcium, phosphate, magnesium and vitamin D-binding protein were measured before (18–22 weeks′ gestation) and after the intervention (32–36 weeks′ gestation). Free and bioavailable 25(OH)D concentrations were calculated. Regression analysis of covariance (ANCOVA) was applied to assess the effect of the training regime on each substance with pre-intervention levels as covariates. In a second model, we also adjusted for study site and sampling month. Intention-to-treat principle was used. Results A total of 724 women completed the study. No between-group difference in serum 25(OH)D and related parameters was identified by ANCOVA using baseline serum levels as covariates. The second model revealed a between-group difference in levels of 25(OH)D (1.9, 95% CI 0.0 to 3.8 nmol/L; p  = 0.048), free 25(OH)D (0.55, 95% CI 0.10 to 0.99 pmol/L; p  = 0.017) and bioavailable 25(OH)D (0.15 95% CI 0.01 to 0.29 nmol/L; p  = 0.036). No serious adverse events related to regular exercise were seen. Conclusion This study, a post hoc analysis, indicates that exercise may affect vitamin D status positively, and emphasizes that women with uncomplicated pregnancies should be encouraged to perform regular exercise. Trial registration ClinicalTrials.gov: NCT00476567 , registered May 22, 2007.

• Publisher: BioMed Central,Springer Nature B.V,BMC
• Subject: Adult / Bioavailability / Bioavailable 25(OH)D / Calcium - blood / Cardiovascular disease / Clinical trials / Diabetes / DNA-Binding Proteins - blood / Endocrine system / Evidence-based medicine / Exercise / Exercise - physiology / Exercise Therapy - methods / Female / Free 25(OH)D / Gestational diabetes / Gynecology / Healthy Volunteers / Humans / Magnesium / Maternal and Child Health / Maternal health and pregnancy / Medicine / Medicine & Public Health / Norway / Nutritional Status / Parathyroid Hormone - blood / Phosphates - blood / Physical activity / Physical fitness / Pregnancy / Pregnancy Complications - etiology / Prenatal care / Prenatal Care - methods / RCT / Reproductive Medicine / Research Article / Transcription Factors - blood / Ultrasonic imaging / Vitamin D / Vitamin D - analogs & derivatives / Vitamin D - blood / Vitamin D Deficiency - etiology / Vitamin deficiency / Womens health