Vitamin D insufficiency in healthy pregnant women living in Warsaw.

Background/objectives: Ensuring the optimal level of 25-hydroxy-vitamin D (250HD) in serum (concentration above 30 ng/ml) is essential for protecting the health of the mother and the developing fetus. Vitamin D plays an important role in maintaining proper bone structure, preventing infections, reducing the risk of premature birth and gestational diabetes. The aim of the study was to verify whether healthy pregnant residents of Warsaw were deficient in vitamin D.

Material And Methods: The material consisted of 150 serum samples of 50 healthy women in 1st, 2nd and 3rd trimester of pregnancy 72.7% of the sera were from women who reported taking multivitamin supplements containing vitamin D3 (71% out of that group was taking 400 IU daily). The concentration of 250HD was measured using the vitamin D total assay on Elecsys 2010 automatic analyzer (Roche Diagnostics).

Results: The average serum 250HD concentrations of 50 women in 1st, 2nd and 3rd trimester of pregnancy were respectively: 23.1 ng/ml, 24.8 ng/ml, and 25.1 ng/ml, with no statistically significant differences. The optimal levels of 250HD (30-80 ng/ml) were found in 30.0% of samples, hypovitaminosis (20-30 ng/ml) occurred in 38.7%, deficiency (10-20 ng/ml) in 24.0% and severe deficiency (less than 10 ng/ml) in 7.3% of cases. Mean concentration of 250HD in winter season (October 1 - March 31) was 23.6 ng/ml and in summer season (April 1 - September 30) was 25.5 ng/ml, with no statistically significant difference. On the basis of the BMI in 1st trimester two subgroups were distinguished from the studied subjects: BMI <21 (13 patients, 39 samples) and BMI >25 (14 patients, 42 samples). Mean 250HD concentration in these groups were 27.3 and 23.5 ng/ml respectively (p<0.05). High statistical significance (p<0.001) was found among the total number of samples with 250HD deficiency and severe deficiency (<20 ng/ml) and samples with hypovitaminosis and optimal 250HD level (>20 ng/ml) in these groups.

Conclusions: Regardless of trimester and season, vitamin D below the optimal level is a common occurrence during pregnancy and the current level of supplementation among Polish pregnant women appears to be insufficient. Our data suggest that special attention should be paid to the problem of vitamin D insufficiency in overweight pregnant women.