Maternal serum 25(OH)D levels in the third trimester of pregnancy during the winter season

Objective. To measure serum 25(OH) D levels of pregnant women in the last trimester during the winter season and to determine the factors affecting their serum levels. Methods. In all, 79 pregnant women in the third trimester were examined between November 2008 and March 2009. Serum calcium, phosphorus, alkaline phosphatase, parathyroid hormone, and 25(OH) D levels were measured. Maternal age, education, socioeconomic status (SES), nutrition, dressing habits, and level of sunlight exposure were determined and their correlation with serum 25(OH) D levels were statistically compared. Results. The mean serum 25(OH)D level of the study group was 11.95 +/- 7.20 ng/ml, and the prevalence of severe vitamin D deficiency [25(OH)D < 10 ng/ml] in pregnant women was 45.6%. No association was detected between severe vitamin D deficiency and maternal age, gravidity, skin phototype, benefiting from ultraviolet index, and educational status of the cases. Also in patients who used multivitamin supplements and good SES, 25(OH)D levels were significantly higher (p = 0.046, p = 0.025, respectively). Conclusions. This study showed a remarkable high rate of vitamin D deficiency in pregnant women during the winter season and we have found high levels of vitamin D in patients supplemented with multivitamins and in ones with good SES.