What is the Success Rate of IUI?

Female age

Age is not the sole determinant of fertility success, but it does affect your chances of pregnancy. That includes intrauterine insemination. That’s because egg quality and the chances of IUI working decrease with a woman’s age. Additionally, the risk of miscarriage is also four times higher for women over 42, and it keeps increasing as you age. Let’s take a look at some numbers:

Age	IUI success rate (%)
30-34	14.5
35-39	12.6
49-44	10.0
>45	8.9

Ideally, the earlier you start IUI treatment, the better. However, don’t let that deter you. Regardless of your age during the IUI process, there are other factors at work. Let’s take a look at them.

Male age

Most of the fertility talk around age is focused on women. But men’s age can impact IUI success rates as well. Studies found that as men’s age increased, miscarriage rates increased too. Why? Because as a man ages, there is increased sperm DNA fragmentation, as well as an increase in the number of immotile or dead sperm present in the semen. This reduces the overall quality of the sperm, making it harder to get pregnant or sustain a pregnancy. One study found that the miscarriage rate went from 13.7% for men under 30 to 32.4% for men over 45.

Underlying cause of infertility

The success of the IUI procedure is also reliant upon whether underlying causes are involved. There may be unexpected reasons why your IUI success rates aren’t ideal, such as anovulation. One study looked at infertile women with anovulation or other unexplained factors. It found these women had higher IUI success rates than those with endometriosis, blocked fallopian tubes, or uterine abnormalities. In the case of anovulation or issues with egg development, ovarian stimulation paired with IUI treatment can help boost your chances of success. Consider adding the Inito Fertility Monitor to your toolbox as well to rule out anovulation. It measures all 4 fertility hormones – LH (luteinizing hormone), estrogen, PdG (urine metabolite of progesterone), and FSH on a single test strip. LH, estrogen, and FSH are key to tracking your fertile window. And PdG helps confirm ovulation, which is key to getting pregnant. Unfortunately, the story is more complex when it comes to physical fertility struggles (i.e. infertility related to fallopian tubes or congenital uterine anomalies) or conditions such as endometriosis. IUI alone typically can’t serve as a solution. We understand how frustrating this can be. Please talk with your doctor to explore other options that can help you achieve a healthy pregnancy. Know more: Your Guide to Getting Pregnant With Endometriosis

Sperm parameters

Sperm plays a large (and often overlooked) role in fertility, especially when it comes to intrauterine insemination. The quality of a man’s sperm can affect the IUI procedure success rates. One study further exemplifies this. It found that a total progressive motile sperm count (TPMSC) of over 15 million had a very high IUI success rate (a whopping 76.1%!). This refers to the number of swimming sperm that are moving forward progressively. The numbers dropped drastically for a TPMSC of 5-15 million. And even more for less than 5 million.

TPMSC (millions)	Pregnancy rate (%)
<5	8.2
5-15	15.7
≥15	76.1

Another study confirmed these findings. It also uncovered that pregnancy rates were the best with a total motile sperm count (TMSC) greater than nine. TMSC means the number of sperm that are actually swimming. The lower the TMSC count went from there, the lower the IUI success a.k.a. pregnancy rate.

Total motile sperm count (millions)	Pregnancy rate (%)
<0.25	4.18%
0.25–0.49	4.11%
0.50–0.99	3.67%
1.00–1.99	7.45%
2.00–3.99	10.13%
4.00–4.99	11.63%
5.00–5.99	12.87%
6.00–6.99	13.93%
7.00–8.99	14.33%
≥9	16.70%

Note: The sperm count used in these studies is different from what you’d see in a normal semen analysis. That’s because the sperm are washed for the IUI process, and that reduces the sperm count. To accurately track, you need the original sperm count and the post-wash count on the day of IUI.

Ovarian stimulation protocol

The type of ovarian stimulation medication you choose can affect the success rate of IUI. A study on women with PCOS looked into this. It found that live birth rates averaged about the same with the use of clomiphene citrate, letrozole, and gonadotropins. But let’s look at more details. Having multiple eggs released at once increases your chances of twins or triplets. But that does not boost your chances of having a healthy baby. So, it’s best to err on the safe side and only have one egg released at a time. Studies show that letrozole is the best for this, so it’s the top choice for women TTC with IUI.

Type of fallopian tube blockage

Did you know that it only takes one fallopian tube to get pregnant? That means if one of yours is blocked, you can still conceive. But the location of the blockage is important for intrauterine insemination results. The pregnancy rate for women with a blockage that’s close to the uterus (proximal)? It’s about the same as women with unexplained fertility (44.7%). But for those whose blockage is closer to the ovary (distal)? The chances of successful IUI were lower than women with unexplained fertility (11.7% vs. 44.7%).

Number of IUI cycles

There is a sweet spot when it comes to the number of cycles that result in the greatest chances of success. And that sweet spot is between 4 and 5 cycles.

Number of IUI cycles	1	2	3	4	5	6	7
Pregnancy rate	11.16	10.74	7.82	10.0	10.0	10.26	7.69

But the rates also vary depending on your age. One study looked at this in more detail and found the following results. The study found a drop in pregnancy rates with increasing age. But, for the first three cycles, the pregnancy rates for women between 40-41 years did not differ from those aged 35-39. Overall pregnancy rates were constant in women up to the age of 40, even after multiple cycles. Here’s a look at age, the number of cycles, and the resulting success rate. Everyone’s fertility journey is unique. Your fertility specialist is the best person to guide you, and they may suggest other options such as in vitro fertilization (IVF) or other fertility drugs. Now, let’s explore how IUI compares to IVF in terms of success rates.