Svigos 1982.

Methods	Country carried out: Australia. Date conducted: Type of trial design: RCT. Method of randomisation: randomised on formal diagnosis of pregnancy on USS at 6‐7 weeks. Number of centres: 1. Source of funding: none given.
Participants	Total number randomised: 32. Total number for analysis: 16. Inclusions: 2 or more consecutive miscarriages. Exclusions: none given.
Interventions	Treatment arm: IM hCG 9000 units 3 times per week until week 12. Control arm: no treatment. Additional interventions: Duration: from USS confirmation of pregnancy at 6‐7 weeks until week 12.
Outcomes	Early pregnancy loss. Pregnancy complications. Labour complications. Congenital defects.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The method of randomisation was not presented in the paper. However, the author responded that randomisation to either arm of the trial was achieved by generating a random allocation sequence. However, the method of sequence generation is unknown.
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 forms of bias apparent in the study.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Method of blinding not stated in the study.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Method of blinding not stated in the study.

BMI: body mass index 
 hCG: human chorionic gonadotrophin 
 IM: intramuscular 
 IU: international units 
 RCT: randomised controlled trial 
 USS: ultrasound