What Is the Success Rate of IUI Treatment?
Quick Answer
IUI success rates range from 5% to 20% per cycle depending on age, diagnosis, sperm quality, and whether fertility medications are used. Women under 35 typically see 15 to 20% per cycle with medication, and cumulative rates of 30 to 40% after three to four cycles. Most IUI pregnancies occur within the first three to four attempts.
Markham Fertility Centre offers unlimited funded IUI cycles through the Ontario Fertility Program across five locations in Ontario.
IUI Success Rates by Age
Age is the single strongest predictor of IUI success. Per-cycle and cumulative rates based on published clinical data:
| Age group | Per-cycle pregnancy rate | Cumulative rate after 3 cycles | Cumulative rate after 6 cycles |
| Under 30 | 15 to 20% | 40 to 50% | 50%+ |
| 30 to 34 | 10 to 15% | 30 to 40% | 40 to 50% |
| 35 to 37 | 8 to 12% | 25 to 30% | 30 to 40% |
| 38 to 40 | 5 to 8% | 15 to 20% | 20 to 25% |
| 41 to 42 | 3 to 5% | 10 to 12% | Less than 15% |
| Over 43 | Below 2% | Limited cumulative benefit | Most specialists recommend IVF |
The key takeaway: IUI is most effective for patients under 35, where cumulative success over three to four cycles can approach the per-cycle success rate of a single IVF cycle, at a fraction of the cost.
Factors That Influence IUI Success
Success is not determined by age alone. Several other variables play a significant role:
Diagnosis:
| Diagnosis | Impact on IUI success |
| Unexplained infertility | Strongest IUI candidate; 15 to 20% per cycle with medication |
| Ovulatory disorders (PCOS) | High success with medication; ovulation induction normalizes cycle |
| Mild male factor | Moderate success; sperm washing concentrates best sperm |
| Cervical factor | Good success; IUI bypasses the cervix entirely |
| Mild endometriosis | Slightly lower rates; moderate endometriosis may reduce effectiveness |
| Severe male factor | Poor IUI candidate; IVF with ICSI recommended |
| Tubal factor (blocked tubes) | IUI not possible; IVF required |
Medication protocol:
| Protocol | Per-cycle success rate (under 35) |
| Natural cycle (no medication) | 5 to 10% |
| Letrozole or Clomid | 10 to 15% |
| Gonadotropin injections | 15 to 20% |
Medicated cycles consistently outperform natural cycle IUI. Letrozole is now the most commonly prescribed first-line oral medication for IUI cycles.
Sperm quality after washing:
- Total motile sperm count (TMSC) above 10 million: Best IUI outcomes
- TMSC 5 to 10 million: Moderate success; IUI still reasonable
- TMSC below 5 million: Poor IUI prognosis; IVF with ICSI typically recommended
Number of mature follicles:
- 1 follicle: Baseline success rate
- 2 to 3 follicles: Improved odds (some studies show double the per-cycle rate)
- 4+ follicles: Cycle may be cancelled to reduce risk of high-order multiple pregnancy
How Many IUI Cycles Should You Try?
Research consistently shows that most IUI pregnancies occur within the first three to four cycles. After that, per-cycle success drops and the cumulative benefit of additional cycles diminishes:
| Cycle number | Cumulative pregnancy rate (under 35, medicated) |
| After 1 cycle | 10 to 20% |
| After 2 cycles | 20 to 35% |
| After 3 cycles | 30 to 45% |
| After 4 cycles | 35 to 50% |
| After 5 to 6 cycles | Minimal additional gain |
Most fertility specialists recommend 3 to 5 IUI cycles before reassessing. If pregnancy has not occurred after this point, IVF typically offers a better return on time and investment.
In Ontario, there is no lifetime limit on funded IUI cycles through the Ontario Fertility Program, so the financial barrier to additional attempts is lower than in many other jurisdictions.
IUI vs. IVF: When to Switch
The decision to transition from IUI to IVF depends on several factors:
- Age over 38: Per-cycle IUI success drops significantly. IVF offers 20 to 30% live birth rates per cycle at this age.
- 3 to 5 failed IUI cycles: The probability of success with additional IUI attempts declines. IVF provides higher per-cycle odds.
- Diagnosis change: If new findings emerge (blocked tubes, severe male factor, endometriosis progression), IVF may become the better option.
- Time pressure: IVF achieves pregnancy faster due to higher per-cycle rates, which matters when age is a factor.
- Desire for genetic testing: PGT-A is only available with IVF, not IUI.
At Markham Fertility Centre, the transition from IUI to IVF is a collaborative conversation with your physician. MFC offers both treatments on-site, so patients stay with the same care team throughout.
How to Maximize Your IUI Success
- Use fertility medications: Medicated cycles have significantly higher success rates than natural cycles
- Optimize timing: Precise alignment of insemination with ovulation (via trigger shot and monitoring) is critical
- Ensure adequate sperm quality: A TMSC above 10 million post-wash gives the best results
- Maintain a healthy lifestyle: BMI within normal range, no smoking, limited alcohol, and adequate sleep support overall fertility
- Don’t wait too long to reassess: If 3 to 4 cycles have not worked, discuss IVF with your physician rather than continuing indefinitely
Why Patients Choose Markham Fertility Centre for IUI
- Unlimited funded IUI cycles through the Ontario Fertility Program
- Physician-performed IUI: Every insemination by a reproductive endocrinologist
- On-site andrology lab for sperm washing and preparation without transport delays
- On-site dispensary for fertility medications
- Five locations (Markham, Barrie-Innisfil, Oshawa, Orillia, Sudbury) reducing travel burden for frequent monitoring visits
- Seamless transition to IVF if needed, with pain-free egg retrieval and on-site genetics
Start your IUI journey at Markham Fertility Centre →
FAQ
What is the average IUI success rate per cycle?
The average is 10 to 20% per cycle when fertility medications are used. Without medication (natural cycle), rates drop to 5 to 10%. Age, diagnosis, and sperm quality are the primary variables.
Is IUI more successful with medication?
Yes. Medicated IUI (letrozole, Clomid, or gonadotropins) consistently outperforms natural cycle IUI. Gonadotropin-stimulated cycles achieve the highest per-cycle rates (15 to 20%) but also carry a higher risk of multiple pregnancy.
How does IUI success compare to IVF?
On a per-cycle basis, IVF is significantly more effective (40 to 50% for patients under 35 vs. 15 to 20% for IUI). However, 3 to 4 cumulative IUI cycles can approach the success rate of a single IVF cycle at a much lower cost.
Does IUI work after age 40?
Success rates drop below 5% per cycle after age 40. Most fertility specialists recommend IVF at this stage because it offers higher per-cycle success and allows for genetic testing of embryos.
Does IUI success rate improve with donor sperm?
Donor sperm IUI cycles tend to achieve slightly higher per-cycle rates (15 to 20%) because donor sperm has been pre-screened for count, motility, and morphology. This removes male factor variables from the equation, making age and ovulatory function the primary determinants of success.
Is the IUI success rate higher with two inseminations per cycle?
Some clinics perform double insemination (two IUI procedures 24 hours apart in the same cycle). Studies show a small potential benefit in certain cases, but most evidence suggests a single well-timed insemination is equally effective when ovulation is properly monitored. Your physician will recommend the best approach based on your specific cycle.