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. 2015 Feb 25;2015(2):CD007079. doi: 10.1002/14651858.CD007079.pub3

Belizan 1983.

Methods Type of study: simple randomisation into 3 groups.
 Method of treatment allocation: not stated.
 Placebo: yes, starch tablets.
 Sample size calculation: not stated.
 Intention‐to‐treat analyses: yes.
 Losses to follow‐up: 0%.
Participants Location: outpatient clinic of Guatemala Social Security Hospital.
 Time frame: not stated.
 Eligible criteria: age 20 to 35 years, single fetus, without evidence of previous pathology and certain date, not receiving any medical treatment during recruitment.
 Total recruited: 36 pregnant women.
Treatment group 1, n = 11, treatment group 2, n = 11, placebo group, n = 14.
Interventions

  • Treatment Group 1 : 1 g calcium/d.

  • Treatment Group 2 : 2 g calcium/d.

  • Compared with placebo tablets.


Started treatment at 15 weeks until delivery.
Outcomes

  1. BP.

  2. Parathyroid hormone.

  3. Calcium and magnesium level.

  4. Phosphorus level.

  5. Pregnancy outcomes; birthweight, birth length, head circumference.
Notes The authors did not mention how many tablets were provided in calcium 1 g, 2 g and placebo group.
Missing data = 0%.
For data in Analysis 2.4 and Analysis 2.9 the placebo n was halved to enable inclusion of data for treatment groups 1 and 2.
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Unclear risk Quote: "After the patients volunteers to participate the trial. Simple randomisation were used to devise patient into 3 groups, receive 1, 2 g calcium comparing with placebo."
 Comment: method of random sequence generation was not clearly described.
Allocation concealment (selection bias) Unclear risk Comment: allocation concealment was not described.
Blinding of participants and personnel (performance bias) 
 All outcomes Low risk Patients were unaware of group status. Study drug and placebo were the same size and weight and had the same organoleptic characteristics.
Blinding of outcome assessment (detection bias) 
 All outcomes Low risk Only 3 obstetrics and gynaecology residents were in charge of measuring BP, after standardisation with double auricular stethoscope.
Incomplete outcome data (attrition bias) 
 All outcomes Low risk Comment: all enrolled participants were analysed.
MIssing data = 0%.
Selective reporting (reporting bias) Low risk None identified.
Other bias Low risk None identified.