Couples with unexplained subfertility and unfavorable prognosis: a randomized pilot trial comparing the effectiveness of in vitro fertilization with elective single embryo transfer versus intrauterine insemination with controlled ovarian stimulation

In patients with unexplained or mild male subfertility and a poor prognosis for natural conception, one cycle of IVF-eSET might be as effective as three cycles of IUI-COS as primary treatment. Elective single embryo transfer does not seem an effective strategy in preventing multiple pregnancies in this particular population. In the future a strict SET policy (i.e., compulsory SET) might be an option. Our trial provides evidence for the feasibility and highlights the importance of a large definitive trial to determine the effectiveness and side effects of both strategies.