Which Factors Determine IUI Success Rate?


There are different types of fertility treatments that are used to help couples struggling to get pregnant naturally. One of the simplest, most affordable, and low-tech options is intrauterine insemination (IUI)

It involves placing healthy sperm directly inside the uterus around the time the woman is expected to ovulate. This brings the sperm closer to the released egg(s), increasing the likelihood that fertilization and implantation of the resulting embryo will occur. 

It is meant to reduce the time and distance it takes for the sperm to get to the egg, making it easier for fertilization to happen. The woman will likely have been prescribed fertility medications to stimulate ovulation. 

Why IUI is done

IUI can be recommended under several situations involving a couple struggling to get pregnant. Some of the reasons for IUI may include:

  • Unexplained infertility – this is whereby there are currently no established reasons why the couple should not be able to conceive. If both are in good reproductive health but are taking too long to conceive, IUI will be the first treatment option used alongside the use of ovulation-inducing medications to increase the chances of conception. 
  • Use of frozen sperm – if the male partner has had to freeze sperm, perhaps due to undergoing a vasectomy, cancer treatment, or other issues, IUI may be used to allow the female partner to get pregnant with their biological child. 
  • Donor sperm – if the male partner is unable to produce healthy sperm due to azoospermia or other condition, the couple may decide to utilize donor sperm. It can also happen if the woman has no male partner. Donor sperm can be used to help the woman conceive. 
  • Endometriosis-related or ovulatory factor infertility – if the woman is suffering infertility related to problems with ovulation, medication can be used to induce the production of good eggs and coupled with IUI to achieve pregnancy. 
  • Erectile dysfunction – if the male has difficulty achieving or maintaining an erection, it may cause problems when trying to conceive. In this case, sperm can be retrieved from a semen sample and directly placed in the woman’s uterus. 
  • Semen allergy – there are rare cases of women being allergic to the proteins in semen and suffering reactions like swelling, redness, and burning sensation in the vagina. This often results in such couples opting to have intercourse using condoms. IUI allows for sperm to be separated from seminal fluid and directly placed in the uterus, thus allowing the woman to get pregnant without reaction. 

How IUI works 

A semen sample is taken from the male partner, donor, or a frozen sample. It is taken through the process of sperm washing that allows for the collection of a concentrated amount of healthy sperm. This process removes the non-sperm elements of the sample and low-quality sperm. 

The woman is monitored to pinpoint when ovulation is likely to occur. This can be done through an ultrasound or using a urine ovulation predictor kit that monitors the levels of luteinizing hormone (LH). The woman may also be prescribed or administered medication that will help stimulate ovulation. This medication should be taken before the procedure. 

Once ovulation is detected, the doctor will schedule the IUI procedure. During the procedure, a vial with the healthy sperm is connected to a catheter. The catheter is inserted into the woman’s vagina, cervix, and uterus. The healthy sperm is then pushed through the tube and into the uterus. The catheter is then removed. 

The woman will need to wait for at least two weeks before taking a home pregnancy test to ascertain if the procedure was a success. A blood test can be performed two weeks after this to confirm that the woman is pregnant. 

What influences IUI’s success?

Three factors primarily affect the chances of successful IUI. These are the cause of infertility, timing, and age. 

Cause of infertility

The reasons behind a couple’s inability to conceive can impact how well IUI will go. In cases of unexplained infertility, the couple will likely have good reproductive health but simply seem unable to conceive. There is a success rate of 7%-10% per cycle with IUI. This increases to about 15%-25% if fertility drugs are used. 

If the problem lies with male factor infertility, the IUI success rate is about 16.9%. If the woman has a blocked fallopian tube, the IUI success rate will vary between 11.7%-38.1%, depending on the location of the blockage. The closer the blockage is to the uterus, the better the chances of success. 


Timing is crucial when it comes to IUI. The doctor needs to ensure that they track ovulation correctly and perform the procedure when there are the best chances of the sperm and egg quickly meeting each other. When it comes to timing, the success rate of IUI can decline if:

  • The woman suffers from endometriosis
  • The woman suffers from fallopian tube disease
  • The woman has a blocked or removed fallopian tube(s)
  • The woman suffers from pelvic infections
  • The man produces no sperm

Where the man has no sperm, IUI can still be done using donor sperm or a frozen sperm sample. If the doctor feels the chances of success are too low in the above situations, they may recommend alternative treatment options like IVF. 

Also, somewhat related to timing, research has shown that women who remain lying down for 15 minutes after undergoing IUI can have 10% better chances of conceiving compared to those that immediately get up after the procedure. 


Chances of conception tend to decline the older you are. More so for women who have a finite supply of eggs and suffer a gradual decrease in egg quality. These are the likely odds depending on how old the woman is. 

  • For women under the age of 35 years of age, the IUI success rate is 13%
  • For women 35 to 37 years old, the IUI success rate is 10%
  • For women 38 to 40 years old, the IUI success rate is 9%
  • For women over the age of 40 years, the IUI success rate is 3%-9%

If you are looking for some advice on IUI or fertility in general, reach out to one of the teams at First Fertility today.