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In utero exposure to extra vitamin D from food fortification and the risk of subsequent development of gestational diabetes: the D-tect study

Keller, Amélie, Stougård, Maria, Frederiksen, Peder, Thorsteinsdottir, Fanney, Vaag, Allan, Damm, Peter, Jacobsen, Ramune, L. Heitmann, Berit
Nutrition journal 2018 v.17 no.1 pp. 100
confidence interval, food fortification, gestational diabetes, issues and policy, margarine, maternal exposure, maternal nutrition, nutrition risk assessment, odds ratio, regression analysis, spring, vitamin D, women, Denmark
BACKGROUND: The primary aim of this study was to assess whether exposure during fetal life to extra vitamin D from food fortification was associated with a reduction in the risk of subsequently developing gestational diabetes mellitus (GDM). Furthermore, we examined whether the effect of the vitamin D from fortification differed by women’s season of birth. METHODS: This semi-ecological study is based on the cancellation in 1985 of the mandatory policy to fortify margarine with vitamin D in Denmark, with inclusion of entire national adjacent birth cohorts either exposed or unexposed to extra vitamin D in utero. The identification of GDM cases later in life among both exposure groups was based on the Danish national health registers. Logistic regression analyses generating odds ratios (ORs) and 95% confidence intervals (95% CIs) were performed. RESULTS: Women who were prenatally exposed to the extra vitamin D from fortification tended to have a lower risk of subsequently developing GDM than unexposed women (OR 0.87, 95%CI 0.74,1.02, P = 0.08). When analyses were stratified by women’s season of birth, exposed women born in spring had a lower risk of developing GDM compared to unexposed subjects (OR 0.68, 95%CI 0.50,0.94, p = 0.02). CONCLUSION: This study suggests that prenatal exposure to extra vitamin D from mandatory fortification may lower the risk of developing gestational diabetes among spring-born women. TRIAL REGISTRATION: This study is part of the D-tect project, which is registered on NCT03330301 .