IUI vs IVF which is better: an OB-GYN decision guide

Couples often come to clinic with the same question: should we try IUI first, or jump straight to IVF? Asking IUI vs IVF which is better misses the better question, which is what fits your diagnosis, your age, and your budget.

This post lays out both treatments side by side and the evidence on when each one earns its place. If you're at the earlier "do we even need treatment" stage, start with when to consider IVF after TTC.

IUI vs IVF in one paragraph each

IUI (intrauterine insemination) places washed sperm directly into the uterus around the time of ovulation, sometimes paired with mild ovarian stimulation. It still relies on a sperm meeting an egg inside your body and travelling through at least one open fallopian tube.

IVF (in vitro fertilisation) involves ovarian stimulation, surgical egg retrieval, fertilisation in the lab, and an embryo transfer back to the uterus a few days later. The fundamental difference: IUI helps sperm find an egg, IVF makes the embryo in the lab and bypasses the tubes entirely. ^{[src] [src]}

IUI success rate, the honest numbers

The IUI success rate per cycle sits at roughly 10 to 20 percent for women under 35, dropping toward 5 percent or less from age 40. Cumulative success over 3 to 4 cycles runs 30 to 45 percent for younger patients with good-quality sperm and at least one open tube. ^[src]

The clearest candidates for IUI:

• Mild male factor (mildly reduced count or motility, normal morphology)
• Unexplained infertility in women under 35
• Couples using donor sperm
• Same-sex female couples and single women using donor sperm

IVF success rate and cost comparison

Per-cycle live birth from IVF runs roughly 40 to 50 percent under 35, around 32 percent at 35 to 37, and around 10 percent at 40 plus, based on HFEA and SART national data. ^[src] For an age-by-age breakdown, see IVF success rates by age.

The IVF cost comparison varies sharply by country:

• UK: NHS funded where eligible (up to 3 cycles under 40 per NICE, postcode dependent in practice). Private cycles run roughly £5,000 to £8,000 per cycle excluding medication. See IVF cost in the UK, NHS vs private
• US: $15,000 to $25,000 per cycle self-pay, with partial insurance coverage in mandate states and growing employer benefits. See IVF cost in the US, what insurance covers

IUI by contrast costs roughly $300 to $1,000 per cycle in the US, or £800 to £1,500 privately in the UK. Three or four IUI cycles can add up to half of one IVF cycle, which matters when you're weighing the decision.

Unexplained infertility IUI vs IVF

The classic question, unexplained infertility IUI vs IVF, has actual trial evidence behind it. The FASTT (Fast Track and Standard Treatment) trial found that skipping the second round of IUI and moving straight to IVF resulted in a faster time to pregnancy and fewer total cycles overall, without increasing cost per delivery. ^[src]

What this looks like in practice:

• Unexplained infertility, woman under 35: 2 to 3 cycles of medicated IUI is a reasonable starting point before moving to IVF
• Unexplained infertility, woman 38 plus: many specialists recommend going straight to IVF, because each month matters

So when does IUI fail and IVF make sense? When three medicated cycles haven't worked, when age starts working against you, or when the original diagnosis was always pointing toward IVF anyway.

A decision matrix by diagnosis

Diagnosis drives the answer more than anything else. A rough map:

• Mild male factor: start with IUI, move to IVF with ICSI if 3 cycles fail
• Unexplained infertility under 35: 2 to 3 medicated IUI cycles, then IVF
• PCOS with patent tubes: ovulation induction first, then IUI, then IVF if no response
• Blocked or absent fallopian tubes: IVF is the appropriate first step, IUI bypasses nothing useful
• Severe male factor (very low count or motility): IVF with ICSI from the start
• Age 38 plus with reduced ovarian reserve: IVF sooner rather than later, to make the most of remaining eggs

How many rounds of IUI before IVF

The standard ceiling is 3 to 4 medicated IUI cycles. After that, IVF gives a meaningfully better return per attempt. ^[src]

Some pathways switch to IVF after just 2 cycles in women 38 plus, because diminishing returns are real and time is the more expensive resource. Success per cycle drops sharply after attempt 4 in nearly every published series.

If you're asking how many rounds of IUI before IVF and you're already on cycle 3 with no pregnancy, that's the conversation to have at your next appointment, not after cycle 6.

NHS and US pathway differences

What this means for you

IUI vs IVF which is better depends on diagnosis, age, and how much time and money each cycle costs you. IUI is the right first step for mild male factor, unexplained infertility under 35, and PCOS with open tubes. IVF earns its place when tubes are blocked, sperm is severely affected, age is 38 plus, or three IUI cycles haven't worked.

If you want help mapping your specific situation to the right next step, that's the conversation we have in a consultation.

Is IUI worth trying at 39?+

Sometimes, but the window is tight. Per-cycle IUI success at 39 is in the single digits for most diagnoses, and each unsuccessful month uses egg-quality time you can't get back. Most specialists recommend at most one or two IUI cycles at this age before moving to IVF.

Can IUI work with PCOS?+

Yes, when ovulation is induced first (usually with letrozole) and tubes are confirmed open. Many PCOS patients conceive on letrozole alone before needing IUI. If three medicated IUI cycles fail, IVF is the next step.

Does IVF give a baby in one cycle?+

Often, but not always. Per-cycle live birth runs around 40 to 50 percent under 35 and falls with age. Most patients who succeed with IVF do so within two to three cycles, including any frozen embryo transfers.

Is IUI painful?+

Most patients describe it as similar to a smear test, with mild cramping that settles in minutes. No anaesthesia is used. If you find smears very uncomfortable, ask your clinic about positioning options.

Does the NHS fund IUI?+

Increasingly less often. NHS IUI funding has narrowed, and many ICBs now reserve IUI for specific groups (typically same-sex couples and single women using donor sperm). Your GP can confirm your local pathway.

What's the success rate of IUI on the second try?+

Roughly the same as the first cycle, around 10 to 20 percent for women under 35 with a good diagnosis. The cumulative rate across 3 to 4 cycles is what tends to make IUI worth doing as a series, not a one-off.