Vitamin D status and hypertensive disorders in pregnancy

Purpose: Several studies have reported increased risk of preeclampsia when 25-hyrdoxyvitamin D (25 [OH]D) levels are low. The extent to which 25(OH)D may lower risk for hypertensive disorder during pregnancy remains unclear. Methods: Among women enrolled in the Project Viva prenatal cohort in Massachusetts, we examined associations of 25(OH)D levels obtained at 16.4-36.9 weeks of gestation (mean 27.9 weeks) with hypertensive disorders of pregnancy, including preeclampsia (56/1591, 3.5%) and gestational hypertension (109/1591, 6.9%). Results: We did not detect an association between plasma 25(OH)D concentration (mean 58, standard deviation 22 nmol/L) and preeclampsia. For each 25 nmol/L increase in 25(OH)D, the adjusted odds ratio for preeclampsia was 1.14 (95% confidence interval, 0.77-1.67). By contrast and contrary to hypothesis, higher 25(OH)D concentrations were associated with higher odds of gestational hypertension: adjusted odds ratio for gestational hypertension was 1.32 (95% confidence interval, 1.01-1.72) per each 25 nmol/L increment in 25(OH)D. Vitamin D intake patterns suggest that this association was not because of reverse causation. Although the elevated hypertension risk may be due to chance, randomized trials of vitamin D supplementation during pregnancy should monitor for gestational hypertension. Conclusions: These data do not support the hypothesis that higher 25(OH)D levels lower the overall risk of hypertensive disorders of pregnancy. (C) 2014 Elsevier Inc. All rights reserved.