South Africa 1991a.

Methods	Allocation concealment: cards labelled R and Q picked blindly from a box, these identified drug container. Two arms
Participants	32 women at 12 to 30 weeks' gestation with a singleton pregnancy and BP >/= 140/90 mmHg x 2 at least 6 hrs apart, no proteinuria, no antihypertensive therapy and no other drug treatment.
Interventions	Exp: oral prazosin 1 mg to 5 mg x 3/day. (12 women) Control: oral identical placebo. (20 women)
Outcomes	Women: severe HT, proteinuria, duration of treatment, placental abruption, caesarean section. Babies: perinatal death, gestation at delivery (mean), birthweight, SGA (< 10th centile) preterm delivery (< 37 weeks).
Notes	Method for measuring BP not mentioned. The trial stopped early. Funding: no information about funding source. Declaration of interests not described.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described.
Allocation concealment (selection bias)	Unclear risk	Not described. Quote: "...in a randomised way, participants either received...". No further details.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Although identical placebo tablets were used, there is no information about whether it was a double‐blind or a single‐blind trial.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not described.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No.
Selective reporting (reporting bias)	Unclear risk	Assessment from published study report.
Other bias	Unclear risk	No information about funding source. Declaration of interests not described.