Fertility Success Rates Using Intrauterine Insemination (IUI)
By and large, birth rates per cycle of IUI performed for the correct indications are reported to be about
- 15% for women under the age of 30,
- 12% for women ages 30 to 35,
- 7% to 8% for women ages 35 to 39, and
- less than 2% for women over the age of 40.
The following summarizes the results with IUI in various circumstances.
- The best results with IUI are obtained when gonadotropins (e.g., Gonal f and Folistim) are used to induce ovulation. The two exceptions are artificial insemination using donor sperm and cases of cervical mucus hostility (unrelated to antisperm antibodies) where insemination during natural cycles in normally ovulating women produces equally good results in both situations. The pregnancy rate in these categories is around 20% per cycle of treatment.
- When clomiphene citrate is used for ovarian stimulation, the success rate is about one-half that achieved through the use of gonadotropins.
- The best results with IUI are obtained in cases of unexplained infertility, abnormal ovulation, cervical mucus hostility unrelated to sperm antibodies, and when donor sperm is used.
- The poorest results with IUI are seen in cases of moderate or severe male infertility (success rates are less than 7% per cycle) and where IUI is performed in natural (unstimulated) cycles where either partner has sperm antibodies.
- Normally ovulating women who have mild pelvic endometriosis (with no pelvic adhesions) also have reduced pregnancy rates (about 6% per cycle following COH). This underscores the fact that even in the absence of pelvic adhesions or damage to the fallopian tubes and ovaries, endometriosis creates an unfavorable pelvic environment that compromises fertilization of the woman’s eggs.
- Pregnancy rates following IUI performed in women over the age of 40 are less than 3% per cycle of treatment. This is probably largely due to the adverse effect of age on egg and embryo quality. This is apparent even when the woman produces a number of large follicles on ultrasound
- Women over 40 rarely achieve viable pregnancy following clomiphene therapy. They do ovulate, but they usually have poor uterine linings and hostile cervical mucus. Therefore women over 40 should probably receive gonadotropins, not clomiphene, because of the urgency brought about by age. Simply put, women over 40 should seriously consider the age factor in choosing between IUI and IVF.