Sabet 2012.

Methods	Randomised, double‐blind trial
Participants	50 pregnant women, in their third trimester, who were scheduled to deliver at Mahdieh Hospital in Tehran.
Interventions	Participants were randomly allocated to 1 of 2 groups: Group 1 (n = 25) received oral vitamin D3 100,000 IU monthly, 3 times; Group 2 (n = 25) control (placebo); until term. Health worker cadre: not specified.
Outcomes	Maternal: the final maternal 25(OH) serum concentrations at delivery, cord 25(OH) vitamin D concentration serum 25(OH), maternal serum iPTH and cord blood iPTH concentration mean PTH concentration Infant: serum vitamin D lower than30 ng/mL in newborn infants Laboratory method used for assessment of vitamin D concentrations: Serum 25 (OH) D concentrations were measured by EIA using the 25(OH) Vit D kit (Immune diagnostic system Ltd, Bolden, UK).
Notes	Total dose of supplementary vitamin D during pregnancy: more than 200,000 IU; start of supplementation: 20 weeks of pregnancy or more; pre‐gestational BMI (kg/m2): unknown/mixed; supplementation scheme/regimen: monthly; skin pigmentation based on Fitzpatrick skin tone chart (Fitzpatrick 1988): mixed/unknown; latitude: north of the Tropic of Cancer; season at the start of pregnancy: unknown. Source of funding: this study was funded by a research grant from the Research Institute of Endocrine Sciences, Shahid Beheshti University of Medical Sciences. Dates of the study and location: 2009 to 2010, Tehran, Iran. Declarations of interest among primary researchers (or state where this information is not reported by the trial authors): no conflict of interest declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants were randomly allocated to the treatment or placebo but methods describing this process were not reported.
Allocation concealment (selection bias)	Unclear risk	The trial reported that it was double‐blinded, but no methods of describing the process were reported.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	The trial reported that it was double‐blinded, but no methods of describing the process were reported.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	The trial reported that it was double‐blinded but they did not specify if those performing the assessments were blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data reported for all 50 participants.
Selective reporting (reporting bias)	Unclear risk	There is insufficient information to permit judgement.
Other bias	Low risk	The study appears to be free of other sources of bias.