Quenby 1994.

Methods	Country carried out: UK. Date conducted: 1989‐1992. Type of trial design: RCT. Method of randomisation: randomised on formal diagnosis of pregnancy on USS prior to 6 weeks' gestation. Number of centres: 1. Source of funding: none given.
Participants	Total number randomised: 81. Total number for analysis: 81. Inclusions: 2 or more consecutive 1st trimester miscarriages; no cause found for recurrent miscarriage after investigations; with or without oligomenorrhoea (variation of > 7 days in menstrual cycle length); any age. Exclusions: BMI > 25.
Interventions	Treatment arm: IM hCG 10,000 units loading dose, 5000 units twice weekly to week 14. Control arm: placebo (normal saline). Additional interventions: all patients received supportive care. Duration: from USS detection of a pregnancy of under 8 weeks' gestation until 16 weeks.
Outcomes	Early pregnancy loss. Late pregnancy loss.
Notes	This study compared hCG versus placebo in patients with regular menstrual cycles and those with oligomenorrhoea. In this study the patients with oligomenorrhoea are able to conceive unaided, rather than patients with polycystic ovaries syndrome, rendering it suitable for inclusion in the analysis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of randomisation not stated.
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not stated.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All patients randomised completed the study.
Selective reporting (reporting bias)	Unclear risk	No reporting bias apparent in the study.
Other bias	Low risk	No other bias apparent in the study.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double blind study.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double bind study.