Bhatia 2012.

Methods	Double‐blind, randomised, placebo‐controlled, multi‐arm parallel trial
Participants	Women over 18 years of age with a singleton pregnancy, with a GA of less than 20 weeks. Exclusion criteria: metabolic disease, complicated pregnancy (e.g. renal or liver disease), medication use for conditions such as tuberculosis or epilepsy and vitamin D supplementation in the previous 3 months (prior to the trial).
Interventions	Participants were allocated to either 1 of the following groups. ‐ Group 1* (n = 100): oral cholecalciferol 60,000 units (in sachets) every 4 weeks ‐ Group 2* (n = 100): 60,000 units (in sachets) every 8 week ‐ Group 3* (n = 100): placebo sachets until delivery *All 3 groups had been provided 1 g elemental calcium daily (groups 1 and 2 without added vitamin D and group 3 with 400 units vitamin D). Health worker cadre: the trial was conducted at the King George’s Medical University, Lucknow, Utter Pradesh, India; tertiary care centre which provide services to people of all socioeconomic strata. Under observation, oral cholecalciferol 60,000 units (in sachets) was administered every 4 weeks (group 1) or every 8 weeks (group 2) or placebo sachets were administered (group 3) until delivery. Calcium tablets were provided for a month at a time. The participants were asked to bring back the empty blisters to check the compliance. All the medications were dispensed in sequentially‐numbered, identical, opaque, sealed packs (carrying the name of the participant) by a research assistant, who was blinded to intervention. The allocation remained concealed for the participants, researcher enrolling and assessing mothers and the one performing data analysis. All the women received standard antenatal care. Maternal serum was measured at recruitment and at term and in cord blood. It is unclear who performed the blood draw or conducted the lab test.
Outcomes	Maternal Secondary Serum 25‐hydroxyvitamin D concentration at term (in nmol/L) Infant Secondary Birth length (cm) Birthweight (g) Head circumference at birth (cm) (not reported) Serum 25OHD concentrations in cord blood (nmol/L) Laboratory method used for assessment of vitamin D concentrations: maternal serum at term and cord blood were collected for 25OHD concentrations, measured by radio‐immunoassay (Diasorin, Stillwater, USA). This assay measured all forms of vitamin D2 and D3. The analytical sensitivity of the assay was 3.75 nmol/L. The intra‐assay and inter‐assay coefficient of variation was 8.6% to 12.5 % and 8.2% to 11 % at different concentrations of 25OHD.
Notes	• Start of supplementation: unknown • Pre‐gestational BMI (kg/m2): indifferent • Supplementation scheme/regimen • Skin pigmentation based on Fitzpatrick skin tone chart (Fitzpatrick 1988):not mentioned • Latitude: north of Tropic of Cancer • Season at the start of pregnancy: not available Source of funding: grant support from Department of Biotechnology (BT/PR/13985/SPD/11/1297/2010) to V. Bhatia, intramural grant to S. K. Sahoo and V. Bhatia from SGPGIMS,Indian Council for Medical Research grant (manpower development scheme) to S. K. Sahoo. Dates of the study: enrolment started in February 2010 Declaration of interests: not available
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was done by a computer‐generated sequence in randomly permuted blocks of hundred.
Allocation concealment (selection bias)	Low risk	All the medications were dispensed in sequentially‐numbered, identical, opaque, sealed packs (carrying the name of the participant) by a research assistant, who was blinded to intervention.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	The allocation sequence was also concealed from all participants; the researcher enrolling and assessing mothers, the researcher assessing offspring and DXA scan images, and performing data analysis.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	The allocation sequence was also concealed from all participants; the researcher enrolling and assessing mothers, the researcher assessing offspring and DXA scan images, and performing data analysis.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Missing data are balanced across intervention groups. Main reason for refusal: DXA, Dual‐energy X‐ray. More relevant outcomes/AEs may be available. e.g.: hypercalcaemia.G1: 100 pregnant women, 54 delivered in the institution, 2 unable to contact, 29 refused DXA; G2: 100 pregnant women; 52 delivered in the institution, 5 unable to contact, 34 refused scan,.
Selective reporting (reporting bias)	Unclear risk	Relevant outcomes results may be available, but are not reported.
Other bias	Low risk	No other bias detected.