IRCT201309277513N4 IRCT 2014-01-03 Isfahan University Of Medical Sciences comparison of effectiveness of Vitamin D supplementation in decreasing the development of the gestational diabetes mellitus in in pregnant women comparison of effectiveness of Vitamin D supplementation in decreasing the development of the gestational diabetes mellitus in pregnant women 2012-03-20 anticipated 70 Complete https://irct.ir/trial/7997 interventional Randomization: N/A, Blinding: Not blinded, Placebo: Not used, Assignment: Parallel, Purpose: Prevention. N/A Gestational Diabetes Melitus. Intervention 1: The study was performed on three groups of 75 pregnant women referring to obstetric clinic of Shahid Beheshti and Alzahra hospital in Esfahan city in 2012 (overall 225 persons) At first, the level of serum vitamin D is measured between 14 to 16 weeks of gestation. Persons with level of below 10 nmol per liter are divided to groups A and B, randomly. Group A are treated with vitamin D supplementation with dose of 50000 unit every two weeks for ten weeks. Group B are not treated with vitamin D supplementation. Among persons with level of above 25 nmol per liter, 75 persons were selected as normal healthy control group. At the end of the study between 24 to 26 weeks of gestation the oral glucose tolerance test was performed in groups A and B (as consumption of 75 gram oral glucose and measurement of blood glucose level 1 and 2 hours later). First hour post-prandial glucose level more than 180 mg per dl and second hour level more than 155 mg per dl or FBS above 95 are considered as impaired glucose tolerance test. Also these two groups are compared with normal control group. Intervention 2: Control group Pregnant women with 14 to 16 weeks of gestational age with serum vitamin D level above 25 nmol/liter. Intervention 3: Study groups 1- Pregnant women with gestational age of 14 to 16 weeks with serum vitamin D level below 10 nmol per liter without vitamin D supplementation 2- Pregnant women with gestational age of 14 to 16 weeks with serum vitamin D level below 10 nmol per liter treated with vitamin D supplementation as 50000 unit dosage every 2 weeks for 10 weeks.