IUI (Intrauterine Insemination): Process, Success Rates, and What to Expect

Updated April 2026 · By the FertilityCalcs Team

Intrauterine insemination (IUI) is often the first fertility treatment recommended because it is less invasive, less expensive, and less time-consuming than IVF. During an IUI, washed and concentrated sperm are placed directly into the uterus around the time of ovulation. While IUI success rates are lower per cycle than IVF, the lower cost allows couples to try multiple cycles for a fraction of the IVF price. This guide covers the IUI process in detail, realistic success rates, and how to know when it is time to consider other options.

How the IUI Process Works

An IUI cycle begins with monitoring your natural cycle or stimulating ovulation with medications. In a natural cycle IUI, your doctor tracks follicle development with ultrasound and triggers ovulation with an hCG injection when the follicle is mature. In a medicated cycle, oral medications like clomiphene or letrozole stimulate the ovaries to produce one to three follicles, increasing the chance that at least one egg is released.

On the day of insemination, the male partner provides a semen sample or a frozen donor sample is thawed. The sample is washed in the lab to concentrate the healthiest, most motile sperm and remove seminal fluid. This process takes 30 to 60 minutes. The concentrated sperm are then loaded into a thin catheter and inserted through the cervix directly into the uterus. The procedure itself takes less than 5 minutes and is usually painless.

Success Rates by Age and Diagnosis

IUI success rates vary significantly by age and underlying diagnosis. For women under 35 with unexplained infertility, the per-cycle success rate with medicated IUI is approximately 10 to 20 percent. For women 35 to 37, it drops to 10 to 15 percent. At 38 to 40, expect 5 to 10 percent per cycle, and over 40, success rates fall below 5 percent per cycle.

Cumulative success rates are more encouraging. After 3 to 4 medicated IUI cycles, the cumulative pregnancy rate for women under 35 reaches 30 to 40 percent. The diagnosis also matters: mild male factor and ovulatory disorders respond better to IUI than unexplained infertility or endometriosis. After 3 to 4 unsuccessful cycles, the incremental benefit of additional IUI drops significantly.

• Under 35: 10-20% per cycle, 30-40% cumulative over 3-4 cycles
• Age 35-37: 10-15% per cycle
• Age 38-40: 5-10% per cycle
• Over 40: below 5% per cycle
• Best for: ovulatory dysfunction, mild male factor, cervical factor
• Less effective for: severe male factor, endometriosis, tubal disease

IUI Cost Breakdown

A natural cycle IUI costs $300 to $1,000 including monitoring and the insemination procedure. Adding oral medications like letrozole or clomiphene adds $50 to $200. Injectable medications (gonadotropins) significantly increase cost to $1,500 to $4,000 per cycle due to drug expense and the additional monitoring required to avoid ovarian hyperstimulation.

Sperm washing typically costs $200 to $500 and is included in many clinic fees. If using donor sperm, add $500 to $1,000 per vial plus shipping. Total per-cycle cost ranges from $500 for a natural IUI to $4,000 for a gonadotropin-stimulated cycle with donor sperm. Three to four cycles typically cost $1,500 to $12,000 total.

• Natural cycle IUI: $300-$1,000
• Oral medication cycle (letrozole/clomiphene): $500-$1,500
• Injectable medication cycle: $1,500-$4,000
• Sperm wash: $200-$500 (often included)
• Donor sperm: $500-$1,000 per vial

Medications Used in IUI Cycles

Letrozole (Femara) has become the preferred first-line medication for ovulation induction in IUI cycles. It produces fewer multiple pregnancies than clomiphene while achieving similar or better pregnancy rates. Typical dosing is 2.5 to 7.5 mg on cycle days 3 to 7. Clomiphene (Clomid) at 50 to 150 mg on cycle days 3 to 7 is the traditional alternative.

For women who do not respond to oral medications, injectable gonadotropins (Gonal-F, Follistim) are used at low doses to stimulate follicle development. This requires careful monitoring with ultrasound to prevent excessive follicle development. If more than 3 mature follicles develop, the cycle may be cancelled to reduce the risk of high-order multiple pregnancy.

When to Move From IUI to IVF

Most reproductive endocrinologists recommend moving to IVF after 3 to 4 unsuccessful IUI cycles. Beyond this point, the per-cycle success rate for IUI drops while IVF offers 40 to 60 percent success rates for women under 38. The cost-per-pregnancy often favors IVF after 3 to 4 failed IUIs.

Certain diagnoses should skip IUI entirely and proceed directly to IVF: severe male factor (total motile count below 5 million), bilateral tubal disease, advanced maternal age (over 40), and diminished ovarian reserve. For these patients, IUI cycles delay effective treatment and reduce the window for IVF success.