A couple’s ability to become pregnant depends on many different factors. IUI is used most often in couples who have:
- Mild male factor infertility. Your partner’s semen analysis, one of the first steps in the medical assessment of infertility, may show below-average sperm concentration, weak motility of sperm, or abnormalities in sperm size and shape (morphology). IUI can overcome these problems because preparing sperm for the procedure helps separate the highly mobile, normal sperm from those of lower quality.
- Cervical factor infertility. Your cervix provides the opening between your vagina and uterus. With intercourse, the sperm swim through the cervical opening into your uterus, then to the fallopian tubes to search for a waiting egg. The fluid produced by the cervix around the time of ovulation is supposed to provide an ideal environment for sperm to travel from your vagina to the fallopian tubes. However, if the cervical fluid is too thick it may impede the sperm’s journey. IUI bypasses the cervix, depositing sperm directly into your uterus and increasing the number of sperm available to meet the awaiting egg.
- Semen allergy. Rarely, women have an allergy to proteins in their partner’s semen, so ejaculation into the vagina causes redness, burning and swelling where the semen has contacted the skin. A condom can protect you from the symptoms, but it also prevents pregnancy. If your sensitivity is severe, IUI can be effective, since many of the semen proteins are removed before the sperm is inserted.
- Unexplained infertility. IUI is often performed as a first treatment for unexplained infertility, sometimes in conjunction with ovulation-inducing medications.