Unidentified factors are considered the explanation for infertility when semen in the man and ovulation and fallopian tubes in the woman are normal.

When no explanation for infertility is identified, the following approach is used:

• Women are given a fertility drug (clomiphene), which stimulates several eggs to mature and be released, and human chorionic gonadotropin (hCG), which triggers ovulation, for up to three menstrual cycles. This treatment may result in more than one fetus.
• Semen is placed directly in the uterus to bypass the mucus (intrauterine insemination) within 2 days after ovulation is triggered by treatment with fertility drugs.
• If pregnancy does not result, other assisted reproductive techniques, such as in vitro fertilization, are tried.

If clomiphene plus hCG is unsuccessful, women are sometimes given human gonadotropins (see Infertility: Human gonadotropins) before assisted reproductive techniques are tried. Women have the same chance of pregnancy (about 65%) whether in vitro fertilization is done immediately after unsuccessful treatment with clomiphene plus hCG or whether human gonadotropins are given next, before in vitro fertilization is tried. However, women become pregnant more quickly and are less likely to have a pregnancy with three or more fetuses when in vitro fertilization is done immediately after unsuccessful treatment with clomiphene plus hCG than when human gonadotropins are given next.

Last full review/revision February 2013 by Robert W. Rebar, MD