Poster Topical Area: Vitamins and Minerals
Location: Hall D
Poster Board Number: 465
Objectives: To examine the effect of vitamin D supplementation during pregnancy on blood pressure across gestation.
Methods: We examined longitudinal blood pressure (BP) measurements within the Maternal Vitamin D for Infant Growth trial, a randomized controlled trial of maternal vitamin D supplementation in Dhaka, Bangladesh. Women (n=1300) were enrolled at 17-24 weeks gestation and randomized to 1 of 5 vitamin D supplementation groups: placebo, 4200 IU/week, 16800 IU/week, 28000 IU/week during pregnancy and placebo from 0-6 months postpartum, or 28000 IU/week during pregnancy and 0-6 months postpartum. BP was measured using an automated digital blood pressure monitor. Two measurements were taken at least one minute apart and a third reading was taken if systolic BP (SBP) or diastolic BP (DBP) measurements differed by >10 mmHg. BP was measured at enrollment, 24 weeks, 30 weeks and weekly from 36 weeks gestation until delivery. Gestational hypertension was defined as SBP ≥140 mmHg or DBP ≥90 mmHg at any point after enrollment. Mixed effect models were used to analyze treatment effect of vitamin D on SBP or DBP across gestation; logistic regression was used to assess relative odds of gestational hypertension.
Results: Among 1194 women with complete blood pressure data, the mean (SD) SBP and DBP were 98.7 (9.4) mmHg and 61.9 (7.1) mmHg at baseline; 104 (11) mmHg and 68.1 (9.1) mmHg from after enrollment until delivery. The prevalence of gestational hypertension was 5.2%. The highest dose of vitamin D increased both SBP 1.28 mmHg [95% CI (0.1, 2.3)] and DBP 1.10 mmHg [95% CI (0.1, 2.0) compared to placebo. There was no effect of vitamin D on BP across gestation for the low [SBP 1.09 (-0.1, 2.3) and DBP 0.58 (-0.4, 1.6)] and mid [SBP 0.21 (-1.0, 1.4) and DBP 0.03 (-1.0, to 1.0)] doses compared to placebo. Vitamin D did not impact the odds of gestational hypertension.
Conclusions: In a population of women with low vitamin D status and relatively low BP, vitamin D supplementation at the tolerable upper intake level in pregnancy, but not lower doses, resulted in an increase in BP across gestation while not increasing risk of gestational hypertension. These findings do not support a beneficial role of vitamin D in reducing risk of hypertensive disorders of pregnancy.
The Pennsylvania State University
University Park, Pennsylvania