Brooke 1980.

Methods	Randomised double‐blind controlled trial; 2‐arm design with individual randomisation.
Participants	126 Asian pregnant women 28 to 32 weeks of gestation attending the antenatal clinic at St George's Hospital, London, UK (latitude: 51°30'N, north of Tropic of Cancer). All pregnant women were first‐generation immigrants mostly from India, Pakistan, Bangladesh, Sri Lanka, Mauritius and east Africa. Exclusion and elimination criteria: preterm deliveries, congenital malformations and maternal illnesses likely to affect fetal growth (such as diabetes) although these data are not presented.
Interventions	Participants were randomly allocated to 1 of 2 groups: group 1 (n = 59) received daily 1000 IU vitamin D (ergocalciferol‐D2) daily until term (estimated total dose: 56,000 to 84,000 IU); and group 2 (n = 67) received a placebo until term. Start of supplementation: 28 to 32 weeks gestation. Length of the intervention/follow‐up: 8 to 12 weeks from supplementation to term. Health worker cadre: St George's Hospital Medical School, London, UK. Medical doctors that were part of the team conducted the measurements and provided the supplements.
Outcomes	Maternal: maternal weight gain, dietary vitamin D intake, 25‐hydroxyvitamin D (25‐OHD) concentrations in cord blood and at term. Plasma calcium (adjusted for albumin concentration), inorganic phosphate, bilirubin, albumin concentrations and total alkaline phosphatase activity, alanine transaminase and ʏ‐glutamyl transferase activities, vitamin D binding globulin concentration, compliance. Infant: weight, crown‐heel length, crown‐rump length, rump‐heel length, occipitofrontal head circumference, forearm length, lower leg length, triceps and subscapular skinfold thickness, fontanelle area, plasma cholecalciferol at day 3 and day 6. weight, length and head circumference at 3, 6, 9 and 12 months. Laboratory method used for assessment of vitamin D concentrations: Serum 25‐hydroxyvitamin D was measured by competitive protein binding assay after chromatographic purification of lipid extracts of serum.
Notes	Total dose of supplementary vitamin D during pregnancy: 5 more than 56,000 to 200,000 IU; start of supplementation: 20 weeks of pregnancy or more; pre‐gestational BMI (kg/m2): unknown/mixed; supplementation scheme/regimen: daily; 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: authors report that to avoid distortion of the results due to seasonal variation in sunlight hours the trial was carried out during autumn and winter 1977, the whole of 1978 and spring and summer 1979. Source of funding: the pathological research fund, St George's Hospital Medical School, and the South‐west Thames Regional Health Authority. This study was funded by a combination of a research grant and non governmental organisations. Dates of the study and location: autumn and winter 1977, the whole of 1978 and spring and summer 1979, London, UK. Declarations of interest among primary researchers (or state where this information is not reported by the trial authors): none declared.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Trial reported random allocation to the groups, although the method of sequence generation was not described.
Allocation concealment (selection bias)	Unclear risk	The trial reported that it was double‐blinded but the method of concealment was not described.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	The trial reported that it was double‐blinded.
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	High risk	Unclear number of randomised participants. Preterm deliveries, congenital malformations, and maternal illnesses likely to affect fetal growth (such as diabetes) were eliminated from the trial. There is not complete documentation of the exclusions.
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. There were no significant baseline differences between the groups in maternal age, parity, height, vegetarian: non‐vegetarian ratio or the distribution of the various countries of origin.