Asemi 2012.

Methods	Randomised single‐blinded controlled trial with 2 arms: vitamin D plus calcium and placebo.
Participants	54 pregnant women at risk for pre‐eclampsia, primigravida, aged 18 to 35 years old carrying singleton pregnancy at their third trimester attending maternity clinics affiliated to Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran (latitude: 33.9889° N, 51.4772° E). Exclusion criteria: maternal severe pre‐eclampsia, IUFD, placenta abortion, preterm delivery and GDM.
Interventions	Participants were randomly allocated to 1 of 2 groups: group 1 (n = 27): women received 500 mg of carbonate calcium plus 200 IU of vitamin D (cholecalciferol‐D3) daily for 9 weeks; group 2 (n = 27): women received placebo. The intervention lasted 9 weeks overall, starting at 25 weeks of pregnancy until week 34. Participants were asked not to alter their routine PA or usual diets and not to consume any supplement other than the one provided to them by the investigators. Health worker cadre: the trial was carried out in maternity clinics affiliated to Kashan University of Medical Sciences, Kashan, Islamic Republic of Iran and the investigators provided the supplements to the participants.
Outcomes	Maternal: body weight and height, BMI, fasting plasma glucose levels, serum total cholesterol, triglycerol concentrations, serum HDL‐cholesterol, serum LDL‐cholesterol levels, dietary intakes, total HDL: cholesterol ratio, gestational diabetes, severe pre‐eclampsia, preterm delivery. Laboratory method used for assessment of vitamin D concentrations: serum 25‐hydroxyvitamin D concentrations were measured using a commercial ELISA kit (Immuno Diagnostic Systems). The inter‐ and intra‐assay coefficient of variation for serum 25(OH)D assays ranged from 5% to 7.5%.
Notes	Total dose of supplementary vitamin D during pregnancy: 56,000 IU vitamin D or less; start of supplementation: 20 weeks of pregnancy or more; pre‐gestational BMI (kg/m2): overweight; 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: mixed/unknown. Source of funding: study was funded by research grant from the Vice‐Chancellor for research, KUMS, and Iran. Dates of the study and location: April 2011 to February 2012, Iran. 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)	Low risk	Trial reported randomisation performed by the use of computer‐generated random numbers.
Allocation concealment (selection bias)	Low risk	Trial reported that the appearance of the placebo capsules, such as colour, shape, size, and packaging, was identical to the vitamin D3 capsules.
Blinding of participants and personnel (performance bias) All outcomes	High risk	The trial reported that it was single‐blinded. Participants were blinded to the interventions so it is assumed that the research staff were not blinded.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Trial is reported as single‐blinded and the methods for concealment of the intervention were described for participants. Therefore, it is assumed that it was not blinded to research staff.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Lost to follow‐up of 3 women in the vitamin D group due to preterm delivery (n = 1), IUFD (n = 1), and placental abruption (n = 1). 3 women in the placebo group were also excluded for the following reasons: gestational diabetes (n = 1), preterm delivery (n = 1), and severe pre‐eclampsia (n = 1).
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.