Sablok 2015.

Methods	Randomised controlled trial with 2 arms, with randomisation at the individual level from years 2010 to 2012.
Participants	180 primigravidae women with singleton pregnancy at 14 to 20 weeks in the Department of Obstetrics and Gynaecology in Safdarjung Hospital, New Delhi, India (28°38′08″ N, 77°13′28″ E north of Tropic of Cancer). Pregnant women with pre‐existing osteomalacia, known hyperparathyroidism, renal, liver dysfunction, tuberculosis, sarcoidosis and women not willing to comply to the study protocol were excluded.
Interventions	Participants were randomly assigned to 1 of 2 groups: group 1 (n = 60) did not receive any supplementation of vitamin D; group 2 (n = 120) received vitamin D (cholecalciferol‐D3) supplementation in dosages depending upon the level of serum 25(OH)‐D levels estimated at entry into the study. Participants from this second group with sufficient levels of vitamin D (serum 25(OH)‐D levels > 50 nmol/L), received only 1 dose of 60,000 IU vitamin D (cholecalciferol‐D3) at 20 weeks; participants with insufficient levels of vitamin D (serum 25(OH)‐D levels 25–50 nmol/L) received 2 doses of 120,000 IU vitamin D (cholecalciferol‐D3) at 20 weeks and 24 weeks; and participants with deficient levels of vitamin D status (serum 25(OH)‐D levels < 25 nmol/L) received 4 doses of 120,000 IU vitamin D cholecalciferol‐D3) at 20, 24, 28 and 32 weeks. Independently of the dose, all participants in group 2 were grouped and compared to group 1 for this analysis. Health worker cadre: unclear what the roles of the researchers and other workers in the health worker cadre.
Outcomes	Maternal: preterm labour, pre‐eclampsia, gestational diabetes, serum 25(OH)‐D concentration, serum calcium, phosphorus and serum ALP levels. Infants: Apgar score, birthweight, LBW, 25(OH)‐D concentration in cord blood, small‐for‐gestational age; appropriate for gestational age. Laboratory method used for assessment of vitamin D concentrations: serum 25‐hydroxyvitamin D was quantified by sandwich ELISA.
Notes	By total dose of supplementary vitamin D during pregnancy: more than 56,000 to 200,000 IU to more than 200,000 IU of vitamin D; by start of supplementation: 20 weeks of pregnancy, or more; by pre‐gestational BMI (kg/m2): healthy weight; by supplementation scheme/regimen: single given at different weeks of gestation in the supplemented group; by skin pigmentation based on Fitzpatrick skin tone chart (Fitzpatrick 1988): mixed/unknown; by latitude: north of the Tropic of Cancer; by season at the start of pregnancy: all year round. Authors report that sufficient levels of vitamin D were seen in 93.3% women who had more than 4 hours of sun exposure every day as compared to 18.5% in those with less than 1 hour of daily sun exposure. Source of funding: self‐funded. Dates of the study and location: 2010 to 2012, India. Declarations of interest among primary researchers (or state where this information is not reported by the trial authors): all the authors have nothing to disclose
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was performed using computer‐generated random number tables.
Allocation concealment (selection bias)	High risk	As participants were assigned to either no intervention or intervention and the intervention dosage depended on the vitamin D status, there was a selection bias based on status of vitamin D at baseline.
Blinding of participants and personnel (performance bias) All outcomes	High risk	The trial did not report if the study was blinded. It is assumed that it was not blinded to participants as one of the groups did not receive any supplementation and the other groups received different doses of vitamin D at different times.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	At the time of delivery, both the groups underwent clinical evaluations and complete anthropometric assessment of the neonate, but it was not reported if staff was blinded to the intervention groups.
Incomplete outcome data (attrition bias) All outcomes	High risk	The level of attrition was different in groups 1 and 2: 3/60 (5%) participants in group 1 and 12/120 (10%) participants in group 2 were lost to follow‐up.
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 evident sources of bias.