L‐Jaramillo 1989.

Methods	Assigned independently in sequence using a table of random numbers. All 106 women enrolled completed the study (calcium 55, placebo 51), 14 women who delivered at 36‐38 weeks excluded (calcium 6, placebo 8), none developed gestational hypertension. These women are included in this review.
Participants	Women recruited at a hospital antenatal clinic in Quito, Ecuador. Dates of recruitment 1984‐1986. Inclusion criteria: nulliparity; age 25 years or less; certain menstrual dates; clinic attendance before 24 weeks' gestation; residence in Quito; normotensive; no medical disorders; not taking medication or vitamin/mineral preparations.
Interventions	Calcium supplementation with 4 calcium gluconate tablets daily, each containing 500 mg elemental calcium, from after 23 weeks' gestation till delivery, vs identical placebo tablets.
Outcomes	Gestational hypertension (BP 140/90 mmHg or more, or rise of 30 mmHg systolic or 15 mmHg diastolic, on 2 occasions 6 hours apart); weekly weight gain, mean (SEM) (calcium 412 (26) vs placebo 452 (28) g); birthweight (3097 (40) vs 2832 (50) g); length of gestation (39.3 (0.08) vs 38.7 (0.07) weeks).
Notes	Quito, Ecuador (altitude 2800 m). 1984 to 1986. An earlier report of apparently the same study gave an incidence of gestational hypertension of calcium 3/46 vs placebo 13/46 (Lopez‐Jaramillo 1987). Source of funding: the study was supported by the Consejo Nacional de Ciencia y Technologia and Consejo Nacional de Universidades y Escuclas Polieenicas, Ecuador. CoI: not stated.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Assigned using a random number table
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double‐blind. Identical containers and tablets prepared by the Faculty of Chemistry and Pharmacy, Central University of Ecuador.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Double‐blind. Identical containers and tablets prepared by the Faculty of Chemistry and Pharmacy, Central University of Ecuador.
Incomplete outcome data (attrition bias) All outcomes	High risk	14 women excluded from the report because they delivered before 38 weeks leaving 43/49 women in the calcium and placebo groups respectively. Data from the 14 excluded women are included in this review.
Selective reporting (reporting bias)	Unclear risk	Not clear
Other bias	Unclear risk	Not clear