Comparison of the Effect of Two Doses of Vitamin D (Vit D-Ca and Vit D-Ca+Vit D) from the 16th Week on Preterm Labor in Pregnant Women

Aims Preterm labor (delivery earlier than 37 weeks) is one of the most common problems with midwifery. Recently, vitamin D deficiencies have been reported with adverse maternal outcomes such as pregnancy toxicity, intrauterine growth limitation, and preterm labor. The aim of this study was to compare the effect of 2 doses of vitamin D (Vit D-Ca and Vit D-Ca+Vit D) from the 16th week on preterm labor in pregnant women. Materials Methods The present single-blind randomized clinical trial was conducted on 202 pregnant women referred to 5 obstetric and gynecological clinics in Bandar Abbas, Hormozgan province, Iran during January 2016 to March 2017. The subjects were selected by randomization sampling method and were randomly assigned into group A (n=150) and group B (n=152). Group A received Vit D-Ca supplements, containing 400 IU/day, and group B received Vit D-Ca supplement plus Vit D (with D3 brand), containing 1000 IU/day from the 16th week of pregnancy until delivery. The subjects were examined from the 16th week of pregnancy until delivery. The data were analyzed by SPSS 21 software, using independent t-test, Mann-Whitney U test and Chi-square test. Findings The incidence of preterm labor in the group receiving Vit D-Ca+Vit D (group B) was 24 (16.0%) and in the group receiving Vit D-Ca alone was 25 (16.7%). There was a significant difference between the two groups in terms of preterm labor (p=0.01). Conclusion Vit D-Ca plus Vit D intake reduces preterm labor in pregnant women more than Vit D-Ca alone intake.