IUI Success Rates - Success with Intrauterine Insemination
Because successful insemination depends on sperm and egg being able to get together in the woman's body and then complete the fertilization process, IUI success depends on the situation in the couple.
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:
IUI is not effective with:
IVF clinic success rates differ greatly
Our success rates vs. national average
Data from 2011 SART Report
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
What are success rates with inseminations?
Chanced for success with intrauterine insemination will be very different in different subgroups of couples depending on the age of the female and the underlying cause of the infertility problem. For example:
- In a 30-year-old woman with infertility due to PCOS, polycystic ovarian syndrome (an ovulation disorder), the IUI success rate is about 20% per month depending on the medications being used.
- However, in a 43 year old doing intrauterine insemination for unexplained infertility, the expected success rate is very low - about 1% per month.
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.
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.
Sperm count and pregnancy with IUI
- Sperm counts are not perfect predictors of fertilizing potential and pregnancy
- Rare pregnancies occur with very low total motile counts of less than 1 million
- The converse is also true. Sometimes "normal sperm" (good numbers) don't fertilize eggs
- A biochemical defect in sperm is not always reflected in what we see with the microscope
|Approximate chance of getting pregnant with 1 month of treatment
Female age under 35, have been trying to get pregnant for 2 years
Female has normal tubes and no significant endometriosis
|Type of Treatment
||Total Motile Sperm Count (in millions)
|Intercourse - Try on your own
|Intrauterine Insemination - IUI
|Stimulation with Clomid plus IUI
| Stimulation with injectables plus IUI
Vitro Fertilization - IVF with ICSI
IVF success is dependent on the clinic
Intrauterine insemination is effective for some cases with sperm quality problems. However, if the total motile count at the time of insemination (after processing) is less than 5 million, chances for pregnancy with IUI are much lower.
If the total motile sperm count is below 1 to 5 million, success is unlikely. Therefore, in vitro fertilization with ICSI (injecting sperm into eggs) is usually done for couples with sperm numbers this low.
Five million is a big number, and sometimes patients say; "why won't it work if there's 5 million – that’s a lot, and doesn't it just take one to do the job?”
- The problem is that with low counts, motility and morphology scores there are often issues with the biochemical and molecular ability to be able to fertilize an egg
- In the end, it is not the numbers that are important, it is the ability of the sperm to function properly in a biochemical process
- Low semen analysis numbers suggest the sperm may not be biochemically competent
Using in vitro fertilization we can force fertilization by using the ICSI procedure. With IVF and ICSI the sperm numbers are not very relevant.
- Biochemical and molecular sperm defects can almost always be overcome by injecting individual sperm into the eggs
- In this sense, men are just DNA donors. If we pick up sperm and inject into eggs and get fertilization - their reproductive job is done
- If the sperm are not biochemically capable of fertilizing eggs, putting them higher in the uterus with IUI will not solve the fertility problem. Therefore, with severe sperm problems chances for IUI success are very low.
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 has been investigated in many studies. In couples with a young 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
- Usually by that point couples move on to IVF if IUIs have not been successful
- Chances for success with IVF are very good in young women regardless of whether IUIs have worked or not
IUIs and female age
After the early 30's, advancing female age has a significant negative impact on fertility - regardless of the method used to get pregnant.
One published study of over 4000 Clomid plus IUI cycles showed IUI success rates as shown in the table. (Reference: Serena Dovey, et al, Clomiphene citrate and intrauterine insemination:
analysis of more than 4100 cycles, Fertility and Sterility; December, 2008).
|Age and Success Rates from Clomid-IUI
Per Cycle Completed
IUI success rates over age 40
- It is well known that chances for success with IUI in women over age 40 are much lower. The results of several studies have been consistent in showing this.
- Many couples with a female partner over 40 will move fairly quickly to IVF treatment
- Two issues pushing for this are the low success rates with IUIs over 40 and the understanding that there is an ever-shortening fertility window
- The table above shows results from one large study of IUIs using Clomid
- Most studies have shown a success rate (delivery of a baby) at age 41 of about:
IUI and 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 success chances 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
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
First time IUI success rate
- 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 done
- 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 in the first 3 cycles
Why would we have 6 failed IUIs and then IVF success?
- After several failed IUIs, many couples believe that their fertility problem is so severe that they will never get pregnant
- However, their problem was not circumvented with insemination but was with IVF
- Some couples are very inefficient “reproducers” with sex and with IUIs, but very efficient reproducers with IVF
- IVF bypasses many problems that IUI cannot
IUIs vs. IVF – when to move on?
- The short answer is to move on to IVF after 3 failed IUIs
- If the fertility problem is due to a lack of ovulation, maybe try a few more
- If the female is under 30 and ovarian reserve is good, maybe try a few more
- Costs of fertility treatments are a big factor in deciding when to move beyond IUI
- If the female is 40 or older, or ovarian reserve low, consider moving to IVF sooner
- In vitro fertilization is the next step after IUIs - with a much higher success rate
The have been and continue to be many advances with in vitro fertilization technology that resulted in higher odds for success. However in the case of IUI there have not been significant advances in the last 30 years.
Methods to properly process the semen were figured out long ago. The rest of the equation with IUI is interaction between sperm and the female genital tract - and between sperm and egg if female anatomy and sperm quality allow them to get together.
- Since so much is left to nature with IUI, there is not much that we can improve on
- The sperm must swim to the end of the fallopian tube where the egg should be
- The egg has to be able to ovulate from the ovarian follicle and be picked up by the tube
- The sperm must find and fertilize the egg
- These steps are forced with IVF but are left to nature with IUI. Hence the much lower success rates for IUI compared to IVF
- More details about IVF changes and improvements in success over the years
Success rates of regular intercourse vs. IUI
What is the difference in pregnancy rates for couples with fertility problems between trying with regular intercourse versus IUIs?
We are not sure why IUIs increase chances for pregnancy that much. Certainly the sperm is boosted higher in the woman's body (closer to the eggs) and timing is maximized.
- A couple that has been trying for a year and a half and does not have tubal problems, sperm problems or endometriosis has about a 2% chance per month (over the next year) of getting pregnant from regular intercourse
- If a similar couple does Clomid with IUIs, the expected success rate is 10% per month for up to 3 months
IUI success rates and PCOS, polycystic ovarian syndrome
- Women with polycystic ovarian syndrome, 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 pretty good
- However, IUIs are also used in these couples with an even higher success rate
- Clomid or Femara plus IUI with PCOS – 15-20% success per month (for 3 months)
- Injectables plus IUI with PCOS – 20-25% success per month (for 3 months)
- However, multiple pregnancy risks are high with injectables for PCOS
Should one or two inseminations be done per cycle?
- Several studies have addressed this question
- Some studies show no improvement in success with 2 inseminations done on sequential days compared to 1 well-timed IUI
- Others show higher success if 2 inseminations are done on back to back days
- One explanation for the different findings is that if single inseminations are not ideally timed for ovulation, success rates could improve with a double insemination protocol. Then, at least one of the insems might be properly timed.
- Most fertility specialists believe that 1 well-timed IUI is sufficient
IUI success using donor sperm is discussed on the donor insemination page