Benson 2009.

Methods	Randomised controlled trial.
Participants	78 pregnant women between 14 to 18 weeks' gestation at risk, defined as: dark skinned, veiled; with vitamin D deficiency that has not commenced treatment prior to recruitment. Exclusion criteria: women taking barbiturates or anticonvulsants (decreased vitamin D absorption) and severe renal failure.
Interventions	Participants were individually randomised to 1 of 2 groups: group 1 (n = 38): 2000 IU of cholecalciferol orally daily commencing between 14 and 18 weeks' gestation (if still deficient at 28 weeks the dose was doubled to 4000 IU orally daily until birth); group 2 (n = 40): no treatment during pregnancy. The mother received 300,000 IU cholecalciferol orally immediately and the baby 150,000 IU cholecalciferol orally immediately after birth. Health worker cadre: in order to facilitate compliance, encouragement was given from midwifery/medical staff at each 2–4 weekly antenatal visit with additional intervening telephone calls to women with poor compliance. Pill counts were not performed.
Outcomes	Maternal: vitamin D level. Infant: vitamin D level. Laboratory method used for assessment of vitamin D concentrations: serum 25‐OH vit D concentrations were determined by direct competitive chemiluminescence immunoassay for quantitative determination of total serum 25‐OH vit D (LIAISON®) Diasorin 25‐OH vitamin D assay (Stillwater, MN,USA).
Notes	Total dose of supplementary vitamin D during pregnancy: more than 20000 IU vitamin D; start of supplementation: 14 to 18 weeks of pregnancy or more; pre‐gestational BMI (kg/m2): mixed/unknown; supplementation scheme/regimen: daily; skin pigmentation based on Fitzpatrick skin tone chart (Fitzpatrick 1988): mixed/unknown; latitude: south of Tropic of Capricorn; season at the start of pregnancy: all year round. Source of funding: J.E. Benson was a recipient of the Luke Proposch Perinatal Research Scholarship from the Australian and New Zealand College of Obstetrics and Gynaecology Research Foundation enabling her to undertake this research. Study was funded by research grant. Dates of the study and location: between 2008 and 2009, Melbourne, Australia. Declarations of interest among primary researchers (or state where this information is not reported by the trial authors): the authors have no conflict of interest to disclose.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomly allocated (envelopes in a tamper proof box, ratio 1:1).
Allocation concealment (selection bias)	Low risk	Envelopes in a tamper‐proof box, ratio 1:1.
Blinding of participants and personnel (performance bias) All outcomes	High risk	The trial reported that it was single‐blinded. It is assumed that it was not blinded to participants as one of the groups did not receive any supplementation.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Single‐blinded study but authors did not specify if staff performing assessments were blinded.
Incomplete outcome data (attrition bias) All outcomes	High risk	57.9% intervention and 57.5% control data reported.
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.