IUI before IVF: when it is the right step, when it is a delay

Intrauterine insemination is simpler, cheaper, and less invasive than IVF. It is also significantly less effective. Whether IUI is the right next step depends on your diagnosis, age, and the arithmetic of cycles versus time.

What an IUI actually is

On the day of ovulation, a prepared sperm sample (washed, concentrated, and motile sperm only) is placed directly into the uterus through a thin catheter. The procedure takes a few minutes, no sedation needed. It bypasses the cervix and shortens the journey for sperm; it does not bypass the fallopian tubes.

IUI can be done in an unstimulated cycle (natural cycle IUI) or with mild ovarian stimulation using oral medications like letrozole or clomiphene, or low-dose injectables.

Where IUI works

Unexplained infertility, mild male factor (where motile sperm count exceeds about 5 million after wash), cervical factor, ejaculatory dysfunction, and same-sex couples or single parents using donor sperm. Per-cycle success rates range from about 8 to 15 percent for couples under 35, declining steeply with age.

Where IUI does not work

Bilateral tubal blockage. Severe male factor (post-wash motile count under 5 million). Diminished ovarian reserve where time matters more than gentleness. Endometriosis, in many cases. Unexplained infertility in women over 38 – where multiple IUI cycles often consume the time that should have gone to IVF.

The arithmetic that often gets skipped

Three IUI cycles take three months. Three IUI cycles for a 38-year-old with normal workup yields a cumulative success rate of about 25 to 30 percent. The same patient going straight to IVF reaches a cumulative live-birth rate of 50 to 60 percent over the same three to four months. Time is rarely a free variable in fertility care.

The general guidance from major fertility societies: under 35 and unexplained, three IUI cycles before IVF is reasonable. 35 to 38: at most two or three. Over 38: many specialists recommend skipping IUI entirely.

Questions worth asking your doctor

• Given our diagnosis and my age, what is the per-cycle success rate of IUI versus IVF for us?
• How many IUI cycles are we planning before reassessing? What would change our plan?
• What does waiting three months for IUI cost us, in terms of cumulative live-birth probability?
• Will we be doing natural-cycle IUI or stimulated IUI – and what is the difference in success rate and cost?

This essay is educational. Every patient’s situation is different – the right plan is shaped in conversation with a fertility specialist who knows the full picture.