All of the following are known causes of recurrent aboion, except:

SLE is associated with antiphospholipid syndrome (anti cardiolipin antibodies) and is known to cause recurrent aboions. RH incompatibility is a known cause for spontaneous aboion and may lead to recurrent aboions if it remains unrecognized. Syphilis has also lead to recurrent aboion. TORCH is thus the single best answer of exclusion. Ref: Gynaecology for Postgraduates and Practitioners By Sengupta, Pages 187-92; Textbook of High Risk Pregnancy By Hemant Deshpande, Hemant, Pages 248-49