P3C110: Decreasing Adverse Pregnancy Outcomes Through Vitamin D Supplementation in Black American Pregnant Women

Background: In South Carolina, two earlier clinical trials were performed supplementing pregnant women with vitamin D (vitD) to reach a minimal threshold 25(OH)D concentration of 32 ng/mL. The results suggested that by supplementing pregnant Black American women, one could decrease adverse pregnancy outcomes and comorbidities, which in turn, may help decrease the health disparities seen in Black American women during pregnancy, women with the highest rates of pregnancy complications in the US.

Methods: As part of a larger clinical trial, Black American women (n=66) who presented for prenatal care at ≤14 weeks’ gestation were randomized into 1 of 2 treatment regimens of vitD3 where they either received 400 IU (control) or 4400 IU of vitD3/day. Total circulating 25(OH)D concentration served as the indicator of vitD status and was measured monthly. Urinary calcium/creatinine ratios and serum calcium also were measured monthly. The primary outcome was comorbidities of pregnancy as a function of maternal 25(OH)D area under the curve (AUC) measured at steady-state from month 3 of supplementation until delivery. Chi-square analyses were used to compare baseline characteristics within treatment groups. Student’s t-test analyses were used to show differences in mean maternal 25(OH)D area under the curve with pregnancy outcomes.

Results: There were 57 (86.4%) Black American women with comorbidities of pregnancy: 6.1% with gestational diabetes, 9.1% with hypertensive disorders of pregnancy, 6.1% with preterm labor/birth, and 31.8% who delivered by non-repeat cesarean section. Comparing maternal mean 25(OH)D AUC from visit 3 to delivery, the 400 IU group had mean of 77.2 and the 4000 IU group had mean of 135.0 (p < 0.0001). There were no safety concerns based on safety indicators. Mean maternal 25(OH)D AUC concentrations were lower in those who underwent non-repeat cesarean delivery compared to those who delivered vaginally (90.6 v 117.2; p=0.03) and were lower in participants with hypertensive disorders of pregnancy (71.8 v 112.4; p=0.04).

Conclusion: Vitamin D supplementation may have utility in reducing adverse pregnancy outcomes in this population. A larger study with Black American participants, those at greatest risk of pregnancy complications, is warranted.