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.