Kumar 2009.

Methods	Type of study: double‐blinded randomised trial with simple randomisation sequence developed manually. The blinding of study participants and investigators was done by assigning coded numbers to the package. Method of treatment allocation: the packages were distributed to the participants using the random number in sequence. Placebo: yes. Intention‐to‐treat analyses: no, only participants 524 who delivered in hospital. Losses to follow‐up: 28 from 552 = 5.1% (17 in treatment group and 11 in placebo group).
Participants	Location: At Lok Nayak Hospital, New Delhi, India. Time frame: January 2005 and December 2007. Eligible criteria: healthy normotensive primigravidas with non complicated singleton pregnancy, 12‐25 weeks' gestation Exclusion criteria: multiple pregnancy, polyhydramnios, fetal malformation, diabetes, chronic hypertension, renal disease, cardiovascular disease, urolithiasis or BP > 140/90 mmHg. Total recruited 552 pregnant women, treatment group, n = 290, placebo group, n = 262.
Interventions	Oral calcium carbonate 4 tablets daily (500 mg each) compared with placebo, 4 tablets daily, from GA 12‐25 week until delivery.
Outcomes	1. BP. 2. Maternal and neonatal outcomes including: pre‐eclampsia, preterm delivery, induction of labour, CS, fetal distress during labour, meconium during labour, GA at delivery, gestational duration at delivery (wk; < 32, 32 to 36, 37 to 40, > 40), birthweight g, birthweight (kg < 2, 2 to 2.5, 2.5 to 4), small‐for‐gestational age, stillbirth.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Double‐blinded randomised trial with simple randomisation sequence developed manually.
Allocation concealment (selection bias)	Low risk	Allocation concealed by assigning treatment packages with code, which was unbroken until the end of the study. The packages were distributed to the participants using the random number in sequence.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	The blinding of study participants and investigators was done by assigning coded numbers to the package.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	All women were followed up in prenatal clinic in a routine manner.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Losses to follow‐up: 28 from 552 = 5.1% (17 in treatment group and 11 in placebo group).
Selective reporting (reporting bias)	Low risk	The preplanned outcomes were reported.
Other bias	Low risk	None identified.