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31 Does Vitamin D Prophylaxis decrease the incidence of hypertensive disorders of pregnancy?

      Objective

      To determine if Vitamin D prophylaxis decreases the incidence of hypertensive disorders of pregnancy.

      Study Design

      A single center, parallel, open label, randomized control trial was performed in which pregnant women received Vitamin D3 3000 IU daily or no supplement. The primary outcome was the incidence of hypertensive disorders of pregnancy. Based on a power analysis set at 80%, a sample size of 206 women in each group (n=412) was planned for comparison. Maternal serum and cord blood were collected for 25-hydroxyvitamin D assessment. Patients were called to assess compliance with the study protocol. Maternal demographics and pregnancy outcomes were collected from the electronic medical record. Statistical analyses were performed using SPSS V24. Student’s t tests and ANOVA analyses were performed for continuous variables that were normally distributed. Chi-Square or Fisher’s exact tests were performed for categorical variables. Binary logistic regression for the primary outcome was performed adjusting for confounders. The analysis was conducted with an intent to treat model with omission of missing variables. A P value of <0.05 was statistically significant.

      Results

      Enrollment occurred between October 2016 and September 2019. Of the 412 women enrolled, 392 (95.1%) had completed pregnancies for analysis. Demographic characteristics including baseline maternal 25-hydroxyvitamin D (25(OH)D) levels were similar between groups. Compared to women who did not receive Vitamin D prophylaxis, those who did had a significantly higher 25(OH)D delivery serum level (29.18 +/- 11.87 ng/mL vs. 23.79 +/- 9.29 ng/mL; P<0.001) and cord blood level (33.73 +/- 13.68 ng/mL vs. 26.06 +/- 9.72 ng/mL; P<0.001). The incidence of hypertensive disorders of pregnancy was 10.5% (41/392). Vitamin D prophylaxis did not decrease the incidence of hypertensive disorders of pregnancy when compared to controls (13.1% vs. 7.7%; RR 1.7, 95% CI 0.9-2.9; P=0.10).

      Conclusion

      Vitamin D prophylaxis does not prevent hypertensive disorders of pregnancy, but does increase maternal and cord blood Vitamin D levels.
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