Two of the most common fertility treatments are intrauterine insemination (IUI) and in vitro fertilization (IVF). They both help a pregnancy happen when it’s not happening on its own, but they differ a lot in how they work, how involved they are, and what they cost. For many, IUI is their starting point, and IVF is the bigger step if more intervention is needed.
At a glance
IUI — helps the sperm and egg meet inside your body by placing the sperm directly into the uterus.
IVF — does the meeting and fertilizing outside your body, retrieving and combining the two in a lab, then placing the resulting embryo into the uterus.
How IUI works
IUI (intrauterine insemination) is the simpler, lower-tech option. A sperm sample from a partner or donor is “washed” in the lab to concentrate the healthy, moving sperm, then placed directly into the uterus with a thin catheter near ovulation. The insemination takes a few minutes, feels like a Pap smear, and has no real downtime.
IUI gives sperm a head start. Normally only a tiny fraction get past the cervix toward the fallopian tubes, where fertilization happens. IUI skips that swim up and drops a concentrated dose closer to the finish line. But the egg and sperm still have to meet and fertilize on their own. It’s often paired with ovulation-stimulating medication (like letrozole or clomiphene) to encourage one or more eggs to mature.
How IVF works
IVF (in vitro fertilization) is the bigger, more involved treatment, and it manually takes over a lot of the fertility steps. The ovaries are stimulated with medication for about two weeks to mature several eggs at once. The eggs are retrieved directly from the ovaries, sperm is collected and washed, and the two are placed together to fertilize in the lab. The resulting embryos grow for a few days, and one is transferred into the uterus. (We walk through each step in How Conception Works, and Where IVF Steps In)
The key thing is that IVF does the fertilization outside the body, so it sidesteps the fallopian tubes entirely. That’s why it can work when IUI can’t.
Who IUI is usually for
IUI tends to be the first option when the situation is straightforward and the tubes are open. Common reasons it’s a good fit:
- Unexplained infertility, its most common use.
- Mild male-factor issues, such as a slightly low count or motility.
- A cervical factor, where cervical mucus is getting in the way.
- Ovulation problems, paired with medication to trigger ovulation.
- Using donor sperm, a common route for single women and female couples.
- Ejaculatory or erectile difficulties, since IUI doesn’t rely on intercourse.
IUI is often tried first because it’s cheaper, far less invasive, and can work for the right candidate. It’s most effective for people under 35 with open tubes and no major sperm problem.
Who IVF is usually for
IVF is the answer when IUI either won’t work or has odds too low to be worth the time. Common reasons:
- Blocked or damaged fallopian tubes, where IUI simply can’t work, since there’s no clear path for egg and sperm to meet.
- Significant male-factor infertility, where a single sperm may need to be injected directly into an egg (a technique called ICSI).
- Older age or a low egg supply, where waiting through several IUI cycles risks losing time that matters.
- Failed IUI cycles, after a few rounds haven’t worked.
- A need to test embryos for a genetic condition before transfer.
IVF is also the route for some paths to parenthood that IUI can’t cover, like two men building a family with an egg donor and a carrier, or anyone who needs donor eggs.
Success-rates
Success rates are the numbers people lean on hardest, and the easiest ones to misread.
IUI works in roughly 10 to 15% of cycles for good candidates, less as age rises. That’s for a single cycle. Because IUI is usually repeated, often three times sometimes up to six, the cumulative odds climb to around 20 to 40% across those attempts.
IVF works more often per cycle, but the range is enormous and age is the strongest factor by far.
Live birth per intended egg retrieval, own eggs (SART, 2023)
| Age | Rate |
|---|---|
| Under 35 | 42.8% |
| 35–37 | 30.5% |
| 38–40 | 19.4% |
| 41–42 | 9.4% |
| Over 42 | 2.8% |
These count every cycle that starts, including the ones cancelled before retrieval and the ones that never produce a transferable embryo. You’ll often see higher numbers quoted elsewhere because they only count people who made it to a transfer. The difference is between “what are my odds” and “what are my odds if everything goes right.”
A higher IVF success rate doesn’t automatically make IVF the right choice. For someone in their 20s with open tubes and unexplained infertility, several rounds of cheaper, gentler IUI might work just as well without ever needing IVF. Which path makes sense is a decision for you and your doctor, based on your diagnosis, your age, and what you’ve already tried.
Costs
IUI is far cheaper than IVF, usually between $500 and $4,000 a cycle. The spread comes from three things: medication (an oral pill like letrozole is cheap, around $100, while injectable hormones can run into the low thousands), monitoring and bloodwork to track your response ($500 to $1,000), and the insemination itself ($150 to $400).
IVF is a different order of magnitude, well into five figures per cycle before medications. That gap is a big part of why IUI is often tried first: for the right candidate, a few rounds of IUI can cost less than a single round of IVF. We break the IVF numbers down on Understanding Costs.
So which one?
Neither is universally better. The right treatment depends on why a pregnancy isn’t happening and age. For many people with a straightforward picture and open tubes, IUI is a good low-cost first step. For blocked tubes, serious male-factor issues, older age, or after IUI hasn’t worked, IVF is the next step up. A fertility doctor sorts this out based on your specific diagnosis, age, and test results.
Sources
- American College of Obstetricians and Gynecologists (ACOG), Treating Infertility
- ASRM / ReproductiveFacts.org, Intrauterine Insemination (IUI)
- Cleveland Clinic, IUI (Intrauterine Insemination)
- CDC, ART Success Rates
- PMC, Levine et al., “Predicting success of intrauterine insemination using a clinically based scoring system”