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.