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

Abstract

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. Electronic supplementary material The online version of this article (10.1186/s12884-019-2220-z) contains supplementary material, which is available to authorized users.

Exercise: A Possibly Effective Way to Improve Vitamin D Nutritional Status

“…The effect of endurance combined with resistance exercise training intervention on 25(OH)D was investigated in three human studies and one animal study, which did not yield consistent results (Table 3). In the human studies, chronic endurance combined with resistance exercise training intervention significantly increased serum 25(OH)D levels [85,86]. Evans et al found that 4 months of recruit training significantly reduced serum 25(OH)D levels in healthy men with adequate vitamin D {25(OH)D ≥ 20 ng/mL or 50 nmol/L [57]}, while no significant change was observed in healthy women with adequate vitamin D levels [87].…”

Physical activity during pregnancy: a systematic review for the assessment of current evidence with future recommendations

“…Table 5 categorizes main findings with respect to exercise modality and their expected positive results on pregnant-women health and well-being. The favourable health outcomes of performing moderate aerobic exercise were most extensively examined [ 35 , 45 ], followed by strengthening see e.g., [ 42 ], or a hybrid form using both [ 38 , 44 ]. For aerobic exercise, treadmill, walking, and other aerobic-exercise programs are advised (see Table 5 ).…”

The associations between serum trace elements and bone mineral density in children under 3 years of age

“…Also, increased osteoclastic functions have been observed in a state of magnesium deficiency 31 . Magnesium [32][33][34][35] . Clinical studies have shown that serum levels of magnesium are positively associated with calcaneal bone ultrasound analysis of women and negatively associated with the risk of fracture in both men and women 36 .…”