Villar 1987.

Methods	Double‐blind, RCT
Participants	Recruitment 1983‐1985. 34 black women from Johns Hopkins Hospital, Baltimore, USA, 18 white women from Rosario, Argentina Inclusion criteria: nulliparous or primiparous; known menstrual dates; age 18‐30 years; singleton pregnancy; negative roll‐over test. Exclusion criteria: underlying medical disorders. Mean calcium intake at 26 weeks was: calcium group: 1129 (SD 736) and placebo group 914 (478).
Interventions	Calcium carbonate 1.5 g (500 mg tablets) from 26 weeks' gestation vs placebo tablets. Women at Johns Hopkins Hospital also received vitamin preparations containing 200 mg calcium and 100 mg magnesium per day.
Outcomes	Weight gain in last trimester of pregnancy; BP increase; gestational hypertension
Notes	Source of funding: grants from the National Dairy Board and the National Dairy Council. CoI: not stated.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	'Randomly assigned' ‐ no other details
Allocation concealment (selection bias)	Low risk	Random numbers in closed envelopes
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Tablets were the same weight, size and colour, prepared by The Johns Hopkins pharmacy and distributed to the 2 hospitals.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Tablets were the same weight, size and colour, prepared by The Johns Hopkins pharmacy and distributed to the 2 hospitals.
Incomplete outcome data (attrition bias) All outcomes	Low risk	< 10% attrition
Selective reporting (reporting bias)	Low risk	Expected outcomes reported
Other bias	Unclear risk	Women at Johns Hopkins Hospital only also received vitamin preparations containing 200 mg calcium/day.