Kalra 2012.

Methods	Randomised clinical trial
Participants	Pregnant women attending the antenatal clinic between 12 and 24 weeks of gestation Participants were excluded from the study if they were already on Ca or vitamin D supplementation, anticonvulsants, antitubercular treatment or had any medical condition that affected Ca and vitamin D metabolism (including renal and hepatic disease).
Interventions	Participants were randomly assigned to: ‐ Group 1: 2 oral doses of 3000 mcg (7500 mcg/300,000 IU) vitamin D3 in the 2nd and again in the 3rd trimester (600,000 IU in total) (n = 48); ‐ Group 2 (comparison): 1 dose of 1500 mcg (60,000 IU) vitamin D (n = 48). Health worker cadre: unclear who did what but it seems that the study team at the antenatal clinic in Queen Mary Hospital, Chhatrapati Sahuji Maharaj (formerly King George’s) Medical University, Lucknow, India (between tropics) took detailed history of and examined the participants at induction and subsequent visits. Detailed anthropometry of the newborn, including weight, length, head circumference and longest diameter of the anterior fontanelle, was measured at birth and subsequently at 3, 6 and 9 months of age. At each visit, history suggestive of lower respiratory tract infections was examined. Investigators who measured anthropometry of infants and followed them were blinded to the mothers’ treatment category.
Outcomes	Maternal AE 25(OH)D at delivery Infant 25(OH)D at birth (cord serum birth length birthweight Laboratory method used for assessment of vitamin D concentrations: 10 mL of maternal blood collected at induction into the study and again at delivery were immediately transported on ice. Serum or plasma was stored at ‐70oC for future analysis of serum 25(OH)D by RIA/immunoradiometric assay (Diasorin).
Notes	• Start of supplementation: second trimester • Pre‐gestational BMI (kg/m2): unknown/mixed • Supplementation scheme/regimen: 2 oral single doses, 2 oral doses in the 2nd and again in the 3rd trimester (600,000 IU in total) • Skin pigmentation based on Fitzpatrick skin tone chart (Fitzpatrick 1988): not available • Latitude: between Tropics • Season at the start of pregnancy: not specified Setting/country: Queen Mary Hospital, Chhatrapati Sahuji Maharaj Medical University, Lucknow, Utter Pradesh, India Source of funding: this study was partially funded by an Indian Council for Medical Research grant (3/2/2006/PG‐MPD‐7) to P. K Dates of the study: not specified Declarations of interest among primary researchers: none of the authors reported a conflict of interest
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was done using random number tables.
Allocation concealment (selection bias)	Unclear risk	Insufficient information to allow judgement.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Insufficient information whether the participants and study team were blinded during the time when the supplements were being given.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	For the outcome serum 25(OH)D levels, it is unclear if it was not blinded but the lack of blinding is unlikely to influence outcome. For the outcome anthropometry at birth, it states that investigators who measured this were blinded to the mothers’ treatment category.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Reasons for high attrition was explained however whether they were similar across the interventions is unclear.
Selective reporting (reporting bias)	Unclear risk	Insufficient information to allow judgment.
Other bias	Unclear risk	The authors reported study limitations, also with the control group (which is not part of this review) and unspecified logistical constraints. Quote "The control group was not a result of the randomisation process, but was a group of women attending the same hospital, whom we could not recruit early enough to give the second trimester medication. Although there was no statistical difference between the groups in a number of biological and biochemical variables, either at registration or at delivery, this is an important limitation to the interpretation of the present results,especially since there was an unexpected trend towards higher median maternal serum 25(OH)D concentration in the usual‐care group compared with group 1. Third, we were unable to test for maternal hypercalcaemia due to logistical constraints."