Maternal antenatal vitamin D status and offspring muscle development: findings from the Southampton Women's Survey.

CONTEXT: Maternal 25-hydroxyvitamin D [25(OH)D] status in pregnancy has been associated with offspring bone development and adiposity. Vitamin D has also been implicated in postnatal muscle function, but little is known about a role for antenatal 25(OH)D exposure in programming muscle development.
OBJECTIVE: We investigated the associations between maternal plasma 25(OH)D status at 34 weeks of gestation and offspring lean mass and muscle strength at 4 years of age. DESIGN AND
SETTING: We studied a prospective UK population-based mother-offspring cohort: the Southampton Women's Survey (SWS). PARTICIPANTS: Initially, 12,583 nonpregnant women were recruited into the SWS, of whom 3159 had singleton pregnancies; 678 mother-child pairs were included in this analysis. MAIN OUTCOMES MEASURED: At 4 years of age, offspring assessments included hand grip strength and whole-body dual-energy x-ray absorptiometry, yielding lean mass and percent lean mass. Physical activity was assessed by 7-day accelerometry in a subset of children (n=326).
RESULTS: The maternal serum 25(OH)D concentration in pregnancy was positively associated with offspring height-adjusted hand grip strength (β=0.10 SD/SD, P=.013), which persisted after adjustment for maternal confounding factors, duration of breastfeeding, and child's physical activity at 4 years (β=0.13 SD/SD, P=.014). Maternal 25(OH)D was also positively associated with offspring percent lean mass (β=0.11 SD/SD, P=.006), but not total lean mass (β=0.06 SD/SD, P=.15). However, this association did not persist after adjustment for confounding factors (β=0.09 SD/SD, P=.11).
CONCLUSIONS: This observational study suggests that intrauterine exposure to 25(OH)D during late pregnancy might influence offspring muscle development through an effect primarily on muscle strength rather than on muscle mass.