IUI Success Rates

This page reviews issues related to IUI success and how various infertility factors impact IUI statistics.

• IUI is short for “intrauterine insemination” – a fertility treatment
• It involves sperm processing (or “washing”) and placing the processed specimen into the uterine cavity with a catheter

IUI can be effective treatment for infertility of some causes including:

• Infertility due to ovulation problems
• Unexplained infertility
• Mild male factor infertility
• Infertility caused by mild endometriosis

IUI is not effective with:

• Blockage of both fallopian tubes
• Severe male factor infertility
• Severe endometriosis
• Severe pelvic scarring
• For these conditions IVF, in vitro fertilization is the treatment of choice

How is IUI done?

• A semen specimen from the male is processed (or “washed”) in the laboratory
• The processed sperm sample is drawn into a sterile catheter
• The catheter is inserted through the cervix and into the uterus
• The sperm is injected into the uterine cavity
• This is a simple procedure and should be similar to a Pap smear for the woman

Details about the IUI process

Drug assisted IUI success rates

Insemination treatment combined with ovarian stimulation with Clomid tablets (clomiphene citrate) vs. insemination after stimulation with injectable gonadotropins (Follistim, Gonal-F, Bravelle, Menopur). Many studies have shown that IUI plus ovarian stimulation gives a higher success rate than insemination in natural menstrual cycles (no stimulation). When we stimulate the ovaries with drugs and do insemination we are basically blasting away with sperm and eggs and maximizing timing. The insemination provides a greater fertility benefit and a smaller additional benefit comes from the extra eggs stimulated by the fertility drugs.

IUI success rates with Clomid or Femara

• Clomid and IUI success rates are about 10% per month for women under 35 if the tubes are open by a hysterosalpingogram (HSG) and semen analysis is normal.
• This statistic holds true for about 3 cycles – after that it is significantly lower.
• If there is any tubal damage, significant endometriosis, or male fertility issue the chance for success with IUI and Clomid is lower Success with Femara (letrozole) and IUI is about the same as with Clomid.

IUI success and injectable medications

The harder we stimulate the ovaries to get additional eggs the higher the expected success rate with insemination. Clomid is a very gentle stimulation, whereas injectables usually stimulate the ovaries harder – resulting in more eggs developing to maturity. Therefore, insemination with injectable gonadotropins gives higher pregnancy rates (and higher multiple pregnancy risks) compared to insemination with Clomid. With Clomid it is very rare to have more than twins but with injectables we often get development of more eggs which increases the risk for multiple eggs to fertilize and implant.

• In women under 35 with open tubes, no endometriosis, and a male with normal semen, the success rate with injectables and IUI is about 15% per month (up to 3 months)
• Multiple pregnancy risks with ovarian stimulation and IUI
• Details about success rates with Clomid alone vs. Clomid plus IUI vs. injectables

IUI with tubal problems

IUIs are sometimes done when there are tubal problems. For example, a woman may have one tube blocked and one tube open, or she may have a partially blocked tube. Insemination can sometimes be successful in these situations. However, the chances for success are significantly reduced with IUIs and tubal problems. The exact success rate depends on the degree of tubal damage. With both tubes completely blocked, there is no chance for success with IUI – IVF is needed. The expected success rate with IUI are very low with severe pelvic distortion from scarring, or significantly damaged fallopian tubes because sperm and eggs will probably not be able to get together properly with these mechanical problems.

IUI for sperm problems – low sperm counts and male factor infertility

• IUI success rates with male infertility are strongly associated with the number of motile sperm available for insemination
• IUI success with male infertility drops as sperm counts, motility percentage and morphology scores drop below normal ranges

Fertility centers often refer to the “total motile post wash” number. For example, if there are 5 million swimming sperm in the sample after laboratory processing, we say it has a “5 million total motile sperm count post wash”. This is what would be inseminated into the uterine cavity.

Pregnancy Success Rates After One Month of Fertility Treatment

Female age under 35, has been trying to get pregnant for 2 years, normal tubes and no significant endometriosis*

IUI for Unexplained Infertility

Unexplained infertility is a very common situation. We say that a couple has unexplained infertility if they have normal sperm, open fallopian tubes, no known endometriosis, and no ovulation problem. Success rates with IUI in couples with unexplained infertility have been investigated in many studies. In couples with a female partner under age 35, studies have shown:

• Clomid plus IUI has about an 8% per month chance for successful pregnancy

• Injectable FSH products (“injectables”) plus IUI give about 12% success per month

• These statistics hold for about 3 months and after that, success rates are much lower. Many couples choose to move on to IVF if IUIs have not been successful.

• Chances for success with IVF are very good for women under 35 regardless of whether IUIs have worked or not.

IUIs and Female Age

After the early 30s, advancing female age has a significant negative impact on fertility – regardless of the method used to get pregnant. One published study of over 4,000 Clomid plus IUI cycles showed IUI success rates as shown in the table below. (Reference: Serena Dovey, et al, Clomiphene citrate and intrauterine insemination: (analysis of more than 4100 cycles, Fertility and Sterility; December, 2008).

IUIs for Endometriosis

Intrauterine insemination statistics with endometriosis in the female are dependent on the severity of the endometriosis. Mild endometriosis has been shown in some studies to give slightly lower success rates with IUI as compared to unexplained infertility. As the severity of the endometriosis increases, the chances of success with insemination drop significantly. For severe endometriosis, IUI success rates are very low. Success rates with IUI for endometriosis have been variable in studies, showing:

• A pregnancy rate of 6.5% for women with endometriosis vs. 15.3% per cycle for unexplained infertility

• Reference: Nuojua-Huttunen et al., Intrauterine insemination treatment in subfertility: an analysis of factors affecting outcome. Human  Reproduction 1999.

• A pregnancy rate of 5.6% for women with advanced endometriosis vs. 22.7% per cycle for mild endometriosis vs. 25.7% for no endometriosis

• Reference: Prado-Perez et al., The impact of endometriosis on the rate of pregnancy of patients submitted to intrauterine insemination. Fertility and Sterility,2002.

• Pregnancy chances with insemination for natural cycle IUIs (no drugs) with endometriosis are about 2% per cycle vs. 11% with injectables plus IUI for endometriosis.

IUI Success Rates for Polycystic Ovary Syndrome (PCOS)

Women with PCOS have significant ovulation problems. The first-line treatment is usually inducing ovulation with medications. If the woman responds properly to the ovulation inducing drugs, success rates with timed intercourse are typically pretty high. However, IUIs are also used in these couples with an even higher success rate when coupled with Clomid or Femara. These success rates are estimated to be 15-20% success per month (for 3 months).

• Injectables plus IUI success rates are estimated to be 20-25% per month (for 3 months). However, there is a high level of multiple pregnancy risk with injectables for PCOS.

IUI Success Rates During Cycle 1

First time IUI success rates are somewhat higher than for additional attempts. If insemination is increasing the efficiency of the fertility process for a couple, we expect a pregnancy fairly soon. The average success rate per try drops with each attempt, until 3 tries are completed. IUI success after 3 cycles is much lower. Another way to say it – if insemination is going to work, it will be in the first 3 tries. Several studies have shown that 90% of IUI successes are during the first 3 cycles.

Why does IVF work after multiple failed IUI cycles?

After several failed IUIs, many couples believe that their fertility problem is so severe that they will never get pregnant. However, some couples are very inefficient reproducers with only sex and IUIs, but very efficient reproducers with IVF. IVF bypasses many problems that IUI cannot.