The prevalence and clinical associations of hypovitaminosis D in pregnant women from Brazil.

Objective: To study the prevalence and the clinical and demographic associations of hypovitaminosis D in pregnant women from southern Brazil.

Methods: In this cross-sectional study, pregnant women attending prenatal care at two university clinics in Curitiba, Brazil, were investigated for clinical and demographic data and for serum levels of vitamin D, calcium, and parathyroid hormone. Data were collected during summer (January 26 to March 4, 2016) or winter (July 28 to August 31, 2016).

Results: The study included 520 women, with 264 studied in winter and 256 in summer. The median vitamin D level was 53.41 nmol/L; 227 (43.7%) women had vitamin D deficiency (<49.92 nmol/L), 193 (37.1%) had vitamin D insufficiency, and 100 (19.2%) had a normal level (≥74.88 nmol/L). The vitamin D serum level was linked to the season (P<0.001) and the body mass index (P=0.026). Women with HIV infections had a lower prevalence and women with pre-eclampsia had a higher prevalence of hypovitaminosis D (P<0.001 and P=0.025, respectively). The association between pre-eclampsia and low vitamin D status was independent of body mass index, tobacco exposure, maternal age, and pregnancy duration (P=0.043; odds ratio 1.014-2.795).

Conclusion: The rate of hypovitaminosis D in pregnant women from southern Brazil was high. Hypovitaminosis D was more common in winter and was associated with pre-eclampsia.