Comparing the Effect of Different Doses of Vitamin D Supplementation During Pregnancy on Prevention of Adverse Pregnancy Outcomes; a Randomized Clinical Trial

Aims: Repeated pregnancy loss (RPL) is commonly considered as ≥3 fetal losses previously 20 weeks of gestation. Vitamin D has an important role on immune inflection at the maternal‑fetal part. Though, vitamin D can be utilized as a useful approach to treat patients with repeated pregnancy loss. There was lack of consensus on prescribing Vitamin D during pregnancy to prevent pregnancy complications. However, the present study was conducted to compare the effect of low and high dose of Vitamin D on to prevent pregnancy complications.   Materials Methods: We conducted a single-blinded, randomized controlled trial in Yasuj, Iran, to assess the influence of different doses of vitamin D supplement through pregnancy in women on pregnancy and birth outcomes (preterm births and stillbirths, pre-eclampsia, gestational diabetes and low birth weight, Findings: Patients (n=150) in their first trimester were enrolled and randomized to two groups of vitamin D supplementation; 500IU/day (group A; n=70) and 2000IU/day (group B; n=70). 131 patients completed the intervention. Maternal vitamin D supplementation  2000IU/day had a positive effect only on gestational diabetes mellitus, spontaneous miscarriage and preeclampsia and preterm births but there was no statistically significant difference between two groups (p 0.05). Conclusion: Increasing dose from 500 units to 2000 units per day does not increase the effectiveness of vitamin D to decrease pregnancy complications. Vitamin D supplementation (500 IU/day) appeared sufficient to reduce the risk of pregnancy complications as well as the higher dose.