Mojibian 2015.

Methods	Unblinded randomised clinical trial
Participants	Pregnant women with GA 12‐16 weeks who had serum 25(OH) D less than 30 ng/mL. Women with a history of diabetes or participants who consumed vitamin D supplements during the previous 6 months and women with thyroid or parathyroid disorders were deemed not eligible.
Interventions	Women randomised to: Group 1 (n = 250): 50,000 IU vitamin D every 2 weeks orally; Group 2 (n = 250): 400 IU vitamin D daily. Health worker cadre: women were recruited from 2 prenatal clinics (Shahid and Mojibian hospitals) in Yazd, Iran (north of tropics). The study was conducted in 2 prenatal clinics; researchers obtained general information, including maternal age, height, prepregnancy weight, level of education, reproductive and medical histories, and prepregnancy BMI. Assessment of primary outcome, such as gestational diabetes was done by 100 gr oral glucose tolerance test between 24‐28 weeks. The participants delivered at the prenatal clinics (Shahid Sadoughi and Mojibian hospitals). The researchers assessed other outcomes such as serum levels of 25 (OH) D at the time of delivery from mother and cord, neonatal weight, length, head circumference and Apgar of 1 and 5 minutes, as well as other neonatal complications such as macrosomia, respiratory distress and hypoglycaemia.
Outcomes	Maternal Primary gestational diabetes pre‐eclampsia Secondary gestational hypertension serum 25(OH) D level at term Infant Primary preterm delivery low birthweight Secondary birth length birthweight head circumference serum 25(OH) D level in cord blood Laboratory method used for assessment of vitamin D concentrations: 25 (OH) D was analysed by Eliza (Euroimmun Kit, Nima Pooyesh Teb Company, Tehran, Iran) with an inter‐assay coefficient of variation of 7.8% and an intra assay coefficient of variation of 3.2%
Notes	• Start of supplementation: supplementation was started in the 12th week of pregnancy • Pre‐gestational BMI (kg/m2): unknown/mixed • Supplementation scheme/regimen: daily • Skin pigmentation based on Fitzpatrick skin tone chart (Fitzpatrick 1988): not available • Latitude: north of Tropics • Season at the start of pregnancy: all year round regardless of season Source of funding: study was supported by Shahid Sadoughi University of Medical Sciences Dates of the study: between 2010‐2012 Declarations of interest among primary researchers: authors reported no conflict of interest
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random number lists were drawn by an independent researcher.
Allocation concealment (selection bias)	Unclear risk	insufficient information to allow judgment.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants and researchers were not blinded to treatment assignment.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Participants and researchers were not blinded to treatment assignment.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Reasons for missing outcome data unlikely to be related to true outcome.
Selective reporting (reporting bias)	Unclear risk	Protocol not available, insufficient information to allow judgment
Other bias	Unclear risk	Protocol not available, insufficient information to allow judgment.