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Title: Antenatal vitamin D supplementation and offspring body composition and muscle strength : a translational approach
Author: Moon, Rebecca Jane
ISNI:       0000 0004 6497 3389
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2017
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The in utero environment to which a fetus is exposed might influence body composition and muscle strength in later life. Modulation of this environment could therefore represent an approach to addressing the increasing burden of obesity and sarcopenia. One potential modifiable exposure is vitamin D. The aim of this work was to explore the determinants of maternal serum 25-hydroxyvitamin D [25(OH)D] status in pregnancy and the use of antenatal vitamin D supplementation to improve offspring growth, body composition and muscle strength. The Southampton Women’s Survey (SWS) is a prospective birth cohort study that included assessment of maternal serum 25(OH)D at 11 (n=2019) and 34 weeks (n=2328) of gestation. Marked seasonal variation in serum 25(OH)D was observed at both gestations (p < 0.001 for both). After adjustment for season, 25(OH)D tracked moderately from early to late pregnancy (r=0.53), but supplementation use and pregnancy weight gain were significantly associated with changes in 25(OH)D status. The offspring of 678 women who had a late pregnancy 25(OH)D measurement were reviewed at 4 years of age. There were no significant associations between maternal 25(OH)D and offspring lean mass (LM) measured by dual-energy x-ray absorptiometry (DXA), but a positive association with grip strength was found (β=0.10 SD/SD, p=0.01). These findings were translated to an intervention study using the MAVIDOS trial, a randomised placebo-controlled trial of antenatal vitamin D supplementation (1000 IU/day cholecalciferol from 14 weeks of gestation until delivery) in women with a baseline 25(OH)D of 25-100 nmol/l. Offspring anthropometry was assessed at birth (n=768), 1 year (n=594) and 2 years (n=577) of age. At 4 years (n=378), body composition was assessed by DXA and grip strength by hand dynamometry. Weight, length/height and measures of adiposity (skinfold thicknesses at birth, 1 and 2 years of age; fat mass measured by DXA at 4 years) did not differ between the randomisation groups at any age (p > 0.05 for all) despite a significantly greater maternal 25(OH)D in the cholecalciferol supplementation group at 34 weeks of gestation (mean difference 24.7 nmol/l, p < 0.001). LM and grip strength at 4 years were also similar, but in women with baseline 25(OH)D < 30 nmol/l, offspring grip strength was greater in those randomised to cholecalciferol (0.70 SD [95% CI 0.02, 1.38], p=0.04). LM did not differ in this subgroup. These findings suggest that 1000 IU/day cholecalciferol supplementation during mid and late pregnancy in women with baseline 25(OH)D 25-100 nmol/l does not improve offspring body composition or muscle strength despite an increase in maternal 25(OH)D status. Supplementation increased muscle strength in offspring of women with the lowest 25(OH)D levels, highlighting the need for further trials of vitamin D supplementation in deficient women.
Supervisor: Harvey, Nicholas Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available