Khoranrodi 2011.

Study characteristics
Methods	2‐arm randomised controlled trial.
Participants	Setting: health centre ‐ Ali Ebn Abi Taleb Inciusion criteria: third trimester of pregnancy, single pregnancy, no consumption of any drug excepts for iron and multivitamins Exclusion criteria: irregular use of medication, PLP, unwilling to complete forms
Interventions	Intervention group: 500 mg calcium, daily for 4 weeks Control group: 1 placebo capsule (lactose Merk) daily for 4 weeks
Outcomes	Frequency and severity of leg cramp
Notes	Clinical Trials.gov ID IRCT201009274824N1 Dates of study: 2011‐02‐05 Funding sources: Research Managment Affairs, Bushehr University Of Medical Sciences Declarations of interest: there are no conflicts of interest.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Study states that it was “randomised”, but there is no description of the method.
Allocation concealment (selection bias)	Unclear risk	Not specifically described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Both healthcare providers and women were masked to treatment assignment.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Women self‐reported outcomes. The treatment assignment was not revealed until data collection was completed.
Incomplete outcome data (attrition bias) All outcomes	Low risk	4 women were excluded. Reasons are given
Selective reporting (reporting bias)	Low risk	Assessed from study protocol and published report, all prespecified outcomes reported.
Other bias	Unclear risk	Insufficient information available to assess whether another important risk of bias exists.