Niromanesh 2001.

Methods	Type of study: double‐blind, placebo‐controlled clinical trial. Randomly assigned to 1 of 2 treatments. Method of treatment allocation: the manufacturing company coded the tablets. The hospital pharmacy dispensed the tablet among the participants. Stratification: not stated. Placebo: yes, starch tablet. Sample size calculation: not stated. Intention‐to‐treat analyses: yes. Losses to follow‐up: 0%.
Participants	Location: Mirza‐Kochak‐Khan Gynecology Hospital, Tehran, Iran. Time frame: not stated. Eligible criteria: high risk for pre‐eclampsia, positive roll‐over test, GA 28 to 32 weeks, BP < 140/90 mmHg. Exclusion criteria: negative for roll‐over test and had any chronic condition such as diabetes, renal diseases, cardiovascular disease, hypertension, and severe anaemia. Total recruited: 30 women at high risk of pre‐eclampsia (15 in the calcium group, 15 in the control group).
Interventions	2 g of calcium (4 tablets of 500 mg orally every 6 hours). Compared with placebo. Started treatment at 28 to 32 weeks.
Outcomes	Incidence of PIH. Maternal weight gain. Pregnancy outcomes; duration of pregnancy, birthweight.
Notes	No details about the type of calcium.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Thirty women at high risk of preeclampsia were randomly assigned to 2 g of calcium daily intake and placebo regimen." Comment: the method of sequence generation was not described.
Allocation concealment (selection bias)	Low risk	Quote: "The  manufactory company coded the tablets. The hospital pharmacy dispensed the tablet among the subjects."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote:" Randomization and blinding of subjects and investigator were managed by providing coded tablets of the same packaging and physical characteristics for both calcium and placebo tablets."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote:" Randomization and blinding of subjects and investigator were managed by providing coded tablets of the same packaging and physical characteristics for both calcium and placebo tablets." Blood pressure and proteinuria were evaluated in each visit.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "There was no loss to follow up in the course of study." Missing data = 0%.
Selective reporting (reporting bias)	Low risk	None identified.
Other bias	Low risk	None identified.