Vitamin D Status in Pregnancy and Determinants in a Southern European Cohort Study

Population-based data on vitamin D status in pregnancy in southern European countries are scarce. We assessed the prevalence and determinants of vitamin D insufficiency and deficiency in pregnancy in Spain.

Plasma 25-hydroxyvitamin D3 (25(OH)D3) concentration was measured at the first trimester of gestation in 2,036 pregnant women from several geographical areas of Spain (latitude 39-42°N). Uni- and multivariable regression models were conducted to identify predictors of circulating 25(OH)D3 concentration and vitamin D insufficiency (20-30 ng/mL) and deficiency (<20 ng/mL).

Thirty-one per cent and 18% of women were vitamin D insufficient and deficient, respectively. Season at blood collection, latitude, age, social class, tobacco smoking, physical activity and use of vitamin D supplements were identified as independent determinants of 25(OH)D3 concentration. Lower risk of vitamin D insufficiency and deficiency was associated with summer season at blood collection (RR for insufficiency = 0.34, confidence intervals (CI) 0.25, 0.48; and RR for deficiency = 0.07, 95% CI 0.04, 0.12), southern latitude (RR for insufficiency = 0.71, 95% CI 0.50, 1.02; RR for deficiency = 0.60, 95% CI 0.38, 0.94); use of vitamin D supplements (RR for insufficiency = 0.50, 95% CI 0.35, 0.71; RR for deficiency = 0.24, 95% CI 0.14, 0.41); and strong physical activity (RR for insufficiency = 0.80, 95% CI 0.58, 1.09; and RR for deficiency = 0.67, 95% CI 0.46, 1.03). Higher risk of vitamin D deficiency was related to lower social class (RR = 1.94, 95% CI 1.19, 3.16) and smoking (RR = 1.76, 95% CI 1.23, 2.54).

Vitamin D insufficiency and deficiency are highly prevalent in pregnancy. Recommendations and policies to detect and prevent hypovitaminosis D during pregnancy should be developed taking into account the associated factors.