562: Does antepartum vitamin D3 supplementation prevent preterm birth?

To determine if Vitamin D3 supplementation prevents preterm birth (PTB). A secondary analysis on the efficacy of Vitamin D3 to prevent PTB was completed on a trial performed from 10/2016 - 5/2018. Inclusion criteria: confirmed intrauterine pregnancy 12-16 weeks gestation. Exclusion criteria: women taking Vitamin D3 supplements, or a malabsorption disorder, or carrying anomalous fetus. Women were assigned to receive daily Vitamin D3 3000IU or no supplement in addition to prenatal vitamins. Maternal demographic factors, maternal serum Vitamin D (25(OH)D) levels, and gestational age at delivery were collected from charts. Parametric and nonparametric statistics were calculated. A p value of <0.05 was statistically significant. 210 women were included, 103 in the Vitamin D3 supplementation group and 107 in the no Vitamin D3 supplementation group. The incidence of PTB was 12.9% (27/210). There were no differences in maternal baseline characteristics. (Table 1) Maternal serum 25(OH)D and cord blood levels were significantly higher in the Vitamin D3 supplementation group (28.9 ± 11.1 ng/ml vs 23.3 ± 8.8 ng/ml, p=0.001; 31.5 ± 13.7 ng/ml vs 24.5 ± 9.0 ng/ml, p=0.002 respectively). (Table 1) Vitamin D supplementation was associated with the prevention of PTB prior to 34 and 32 weeks gestation (2.0% vs 11.7%, RR 0.57, 95% CI 0.44-0.74; 1.0% vs. 9.7%, RR 0.54, 95% CI 0.42-0.68 respectively). (Figure 1) Antepartum Vitamin D3 supplementation may decrease the risk of PTB.View Large Image Figure ViewerDownload Hi-res image Download (PPT)