The relationship between maternal 25-hydroxyvitamin D status in pregnancy and childhood adiposity and allergy: an...

Vitamin D insufficiency (defined as <75 nmol l^-1) is widespread among pregnant women around the world and has been proposed to influence offspring outcomes in childhood and into adult life, including adiposity and allergy. Disorders, including asthma and eczema, are on the rise among children. Our aim was to investigate the relationship between maternal 25-hydroxyvitamin D status in pregnancy and offspring adiposity, asthma and eczema in childhood.

Maternal 25-hydroxyvitamin D concentrations were analysed in serum samples collected at 15 weeks' gestation from 1710 participants of the prospective Screening for Pregnancy Endpoints cohort study. The offspring of 1208 mothers were followed up at age 5-6 years. Data collected included height, weight, percentage body fat (PBF, measured by bioimpedance) and history of asthma and eczema. Multivariable analysis controlled for maternal body mass index (BMI), age and sex of the child and season of serum sampling.

Complete data were available for 922 mother-child pairs. Each 10 nmol l^-1 increase in maternal 25-hydroxyvitamin D concentration at 15 weeks' gestation was associated with a decrease in offspring PBF of 0.2% (95% confidence interval 0.04-0.36%, P=0.01) after adjustment for confounders but was not related to child BMI z-score. Maternal mean (±s.d.) 25-hydroxyvitamin D concentration was similar in children who did and did not have asthma (71.7±26.1 vs 73.3±27.1 nmol l^-1, P=0.5), severe asthma (68.6±28.6 vs 73.3±26.8 nmol l^-1, P=0.2) and eczema (71.9±27.0 vs 73.2±27.0 nmol l^-1, P=0.5).

The finding of a relationship between maternal vitamin D status and adiposity in childhood is important, particularly because vitamin D insufficiency in pregnancy is highly prevalent. The association between maternal vitamin D supplementation in pregnancy and adiposity in the offspring merits examination in randomised controlled trials.