During Intrauterine Insemination (IUI), a man’s sperm is introduced into the uterine cavity through a catheter. IUI increases the likelihood of pregnancy because sperm bypass the cervix and a higher number have a chance to get closer to the egg. IUI is typically performed when the sperm and cervical mucus are incompatible, when a man is impotent or suffers from premature ejaculation, or when there is a low sperm count or motility. Sperm may be from a partner or from a donor.