L‐Jaramillo 1990.

Methods	Randomised, double‐blind trial. Stated "Each patient was assigned independently in sequence", and "All women completed the study".
Participants	Women attending a hospital in Quito, Ecuador. Dates of recruitment not stated. Healthy nulliparous women with positive roll‐over test at 28‐30 weeks' gestational age ‐ judged at high risk for gestational hypertension.
Interventions	2000 mg elemental calcium daily, from 28‐32 weeks to delivery, vs placebo starch tablets.
Outcomes	Gestational hypertension (BP > 140/90 mmHg on 2 occasions 6 hours apart); proteinuria (300 mg/L); duration of pregnancy (calcium mean 39.2 (SD 1.2) vs placebo 37.4 (2.3) weeks); birthweight (2936 (396) vs 2685 (427) g).
Notes	Quito, Ecuador (altitude 2800 m). 22 in calcium group, 34 in placebo group. Source of funding: not stated. CoI: not stated.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Authors state that this was a RCT but no details of sequence generation are provided.
Allocation concealment (selection bias)	Unclear risk	No details given about how concealment was achieved or whether tablets looked identical
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Stated double‐blind but no further information
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Stated double‐blind but no further information
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not clear
Selective reporting (reporting bias)	Unclear risk	Not clear
Other bias	Unclear risk	Large discrepancy in size of groups not accounted for