How IUI works, who it's best for, success rates, costs, and when it makes sense to try IUI versus moving directly to IVF.
Intrauterine insemination (IUI) is a fertility treatment where specially washed and concentrated sperm are placed directly into the uterus around the time of ovulation. By bypassing the cervix and depositing sperm closer to the fallopian tubes, IUI increases the number of sperm that reach the egg — improving the odds of fertilization.
IUI is sometimes called "artificial insemination" (AI), though that term is less precise. It's one of the least invasive and most affordable fertility treatments, making it a common first step before IVF for many patients.
IUI success rates are significantly lower than IVF (10–20% per cycle vs. 40–50%), but its much lower cost ($500–$3,000 vs. $15,000–$25,000) makes it a reasonable first-line treatment for many diagnoses. Most REs recommend 3–4 IUI cycles before considering IVF escalation.
IUI works best when sperm can reach and fertilize an egg but need a "boost" to get there. It's most effective for:
Starting on cycle day 2–3, your RE may prescribe ovulation-inducing medication (Clomid, letrozole, or injectable gonadotropins). Monitoring via ultrasound and blood work tracks follicle development. For natural cycle IUI, monitoring confirms ovulation timing without medication.
When the lead follicle reaches 18–22mm, a trigger shot (Ovidrel or Pregnyl) initiates ovulation within 36 hours. Some cycles use LH surge detection via OPK instead of a trigger shot.
The sperm sample is collected 1–2 hours before the procedure and "washed" — a process that separates motile sperm from seminal fluid, dead sperm, and debris. Washing concentrates the best sperm into a small volume (0.5mL) and is necessary to prevent uterine cramping from prostaglandins in semen.
Using a thin, flexible catheter, washed sperm are deposited directly into the uterus. The procedure is similar to a Pap smear — uncomfortable for some but not typically painful. You'll lie down for 10–15 minutes afterward, then go about your day normally.
You'll take a pregnancy test approximately 14 days after insemination. Progesterone supplements may be prescribed during this luteal phase to support implantation.
If your clinic uses OPK-based timing rather than a trigger shot, advanced digital OPKs that detect both estrogen and LH surges provide earlier warning of your fertile window — giving your clinic more scheduling flexibility.
| Protocol | Per-Cycle Success Rate | Best For |
|---|---|---|
| Natural cycle IUI | 5–10% | Regular ovulation, cervical factor |
| Clomid/Letrozole + IUI | 10–15% | Mild ovulatory dysfunction, unexplained |
| Gonadotropin + IUI | 15–20% | Strongest protocol; higher multiple risk |
| Donor sperm IUI | 10–20% | Single parents, same-sex couples |
While single-cycle rates seem modest, cumulative success across 3–4 medicated IUI cycles reaches 30–40% for patients under 35 with unexplained infertility or mild male factor. After 3–4 failed cycles, additional IUI has diminishing returns and most REs recommend transitioning to IVF.
| Component | Natural Cycle | Medicated (Oral) | Medicated (Injectable) |
|---|---|---|---|
| Monitoring (ultrasound/bloodwork) | $200–$500 | $300–$800 | $500–$1,500 |
| Medications | $0 | $50–$200 | $1,000–$3,000 |
| Sperm wash + insemination | $300–$800 | $300–$800 | $300–$800 |
| Trigger shot | $0–$100 | $50–$100 | $50–$200 |
| Total per cycle | $500–$1,400 | $700–$2,000 | $1,800–$5,500 |
If using donor sperm, add $500–$1,000 per vial plus shipping. Most patients purchase 2 vials per cycle as backup.
The IUI-to-IVF decision is one of the most common conversations in fertility treatment. Here's the clinical framework most REs use:
| Factor | Continue IUI | Move to IVF |
|---|---|---|
| Number of failed IUI cycles | 1–3 cycles | 3–4+ failed cycles |
| Age | Under 37 | Over 38 (time is a factor) |
| Male factor severity | Post-wash TMC >10M | Post-wash TMC <5M |
| Diagnosis | Unexplained, cervical, mild male | Tubal, severe endo, DOR |
| Genetic testing needed | No | Yes (requires IVF for PGT) |
| Financial consideration | Limited budget, good prognosis | Insurance covers IVF, or time matters more than money |
A 2020 study in Fertility and Sterility found that for couples with unexplained infertility, going directly to IVF was more cost-effective than 3 cycles of IUI first — when considering both financial cost and time. However, for patients paying out of pocket without IVF coverage, 2–3 IUI cycles remain a reasonable first step given the 20–30x cost difference per cycle.
Medication dramatically improves IUI success by ensuring ovulation occurs and sometimes producing multiple follicles (increasing target count). The three medication tiers:
Currently the most commonly prescribed first-line medication for IUI. Letrozole (2.5–7.5mg, days 3–7 of the cycle) stimulates ovulation with fewer side effects than Clomid and lower multiple pregnancy rates. It's now preferred over Clomid for most patients.
The historical standard for ovulation induction (50–150mg, days 3–7). Clomid is effective but has more side effects (hot flashes, mood changes, cervical mucus thinning) and higher twin rates (~8%) compared to letrozole (~4%). Still used when letrozole doesn't produce adequate follicle response.
The strongest stimulation protocol for IUI, producing the highest success rates (15–20%) but also the highest multiple pregnancy risk (15–20% twins, 3–5% higher-order multiples). Requires close monitoring to avoid hyperstimulation. Used when oral medications fail or for patients wanting to maximize per-cycle odds.
IUI is the most common first-line treatment for patients using donor sperm, including single parents by choice, same-sex female couples, and couples with azoospermia or severe male factor. Key considerations:
For patients using donor sperm who want to attempt insemination at home before committing to clinical IUI, at-home intracervical insemination (ICI) kits provide the necessary supplies. Success rates are lower than clinical IUI, but some patients prefer the privacy and lower cost for initial attempts.
Most REs recommend 3–4 medicated IUI cycles before transitioning to IVF. After 3 failed medicated cycles, per-cycle success rates for subsequent IUI drop significantly. For patients over 38, some REs recommend only 1–2 IUI attempts (or skipping IUI entirely) given time constraints.
Most patients describe mild discomfort similar to a Pap smear — a brief cramping sensation as the catheter passes through the cervix. The procedure takes about 5 minutes. Some patients experience mild cramping for a few hours afterward. Taking ibuprofen 30 minutes before can help.
Yes — most clinics encourage intercourse the evening of IUI or the following day, as it may provide additional sperm to support fertilization. There's no evidence that sex after IUI reduces success rates.
Most clinics want to see a minimum total motile count (TMC) of 5–10 million sperm after washing. Below 5 million post-wash, success rates drop significantly and IVF with ICSI is usually recommended. Some studies suggest optimal IUI outcomes at 10+ million post-wash TMC.
Yes, particularly with medicated cycles. Natural cycle IUI has the baseline twin rate (~1–2%). Clomid or letrozole IUI raises twin risk to 4–8%. Injectable gonadotropin IUI has a 15–20% twin rate and 3–5% higher-order multiple rate. This is why monitoring is essential — cycles with too many mature follicles should be converted to IVF or cancelled.
Cycle tracking, timing intercourse, and optimizing your fertile window — the complete beginner's guide.
Evidence-based supplement protocols for egg quality, sperm health, and overall reproductive wellness.
Find your most fertile days with our evidence-based ovulation prediction tool.