Who is a candidate for IUI? Candidates for IUI (Intrauterine Insemination) are individuals or couples facing certain fertility challenges. Here’s a breakdown of who may be a candidate for IUI: Couples with Unexplained Infertility: When fertility tests cannot pinpoint a specific cause for infertility, IUI may be the first treatment recommended. It offers hope to couples by increasing the chances of conception, and bypassing unidentified barriers in natural conception