IUI explained: who intrauterine insemination is for, and what NICE's 2026 fertility guideline changed

What IUI is

Intrauterine insemination (IUI), sometimes called artificial insemination, is a treatment in which sperm are prepared in the laboratory and placed directly into the womb through a thin tube passed through the cervix. The Human Fertilisation and Embryology Authority (HFEA) explains that the better-quality sperm are first separated from those that are sluggish, not moving or abnormally shaped (HFEA, Intrauterine insemination (IUI)). The sperm may come from a partner or from a donor; in the second case the treatment is called donor insemination.

The key difference from IVF is where fertilisation happens. In IUI, sperm are left to meet the egg inside the body, in the fallopian tube, as they would after intercourse. In IVF, eggs are collected and fertilised in the laboratory and an embryo is transferred to the womb. IUI therefore needs at least one open, healthy fallopian tube and eggs that are released normally or with the help of medication.

What happens in a cycle

The HFEA describes a typical IUI cycle in a few steps:

1. Checking the tubes. Because fertilisation takes place in the tube, the clinic first checks that the fallopian tubes are open, using an ultrasound test, an X-ray or keyhole surgery.
2. With or without drugs. IUI can be done in a natural cycle ("unstimulated") or with fertility drugs that encourage the ovaries to release an egg, or more than one ("stimulated").
3. Monitoring. With fertility drugs, ultrasound scans count the developing follicles. If too many develop, the cycle should be cancelled because of the risk of a multiple pregnancy.
4. Timing. Insemination is timed to ovulation, either with a hormone injection that triggers it or with tests that detect when it is about to happen.
5. Insemination. The washed sperm are injected into the womb. The procedure takes a few minutes and is usually described as relatively painless.
6. Pregnancy test. The clinic gives a date for a pregnancy test; testing earlier can give a misleading result.

How it compares with IVF

The HFEA summarises the trade-off plainly. IUI is less invasive and uses fewer drugs, and one cycle typically costs about a quarter of the price of an IVF cycle. But it is also less successful: the HFEA says success rates for IUI are generally around a third of those for IVF, and many people need several cycles. It also warns that IUI "is not a cheaper/less invasive alternative to IVF" for people with a significant fertility problem: it is unlikely to work with blocked tubes, severe endometriosis, a low ovarian reserve or male factor infertility, and women in their late thirties or over 40 may be advised to go straight to IVF.

The main safety concern is multiple pregnancy. With stimulation, more than one egg may be released, and twins or triplets carry higher risks of premature birth and low birth weight. This is why monitoring scans matter, and why the HFEA tracks multiple births so closely, as described in IVF success rates explained.

What the 2013 guideline said

For more than a decade, NHS fertility care in England and Wales followed NICE clinical guideline CG156, published in February 2013. It advised against routinely offering IUI, with or without ovarian stimulation, to people with unexplained infertility, mild endometriosis or mild male factor infertility who were having regular unprotected intercourse. Instead, it recommended trying to conceive for a total of two years and then moving to IVF. As the HFEA still notes, IUI with a partner's sperm for unexplained infertility was therefore generally not funded by the NHS, and people who preferred it to IVF usually paid privately.

IUI kept a role for specific groups: people who cannot have vaginal intercourse because of a physical disability or a psychosexual problem, people with conditions that require specific help to conceive safely, and people using donor sperm, including single women and same-sex couples.

What NG257 changes

NICE published a new guideline, Fertility problems: assessment and treatment (NG257), on 31 March 2026. It updates and replaces CG156 (NICE, NG257). The changes that concern IUI are these.

• Unexplained infertility: IUI is back as an option. NICE still advises trying to conceive through regular unprotected intercourse for a total of two years before treatment. After that, recommendation 1.38.3 asks clinicians to discuss the options and either consider up to 4 cycles of IUI with ovarian stimulation using gonadotrophins before IVF, or offer IVF.
• Fertility drugs alone are ruled out. Recommendation 1.38.2 says ovarian stimulation should not be offered as a stand-alone treatment for unexplained fertility problems.
• Unstimulated IUI for specific groups. Twelve cycles of unstimulated IUI are offered before considering IVF to people who cannot have vaginal intercourse because of a clinically diagnosed physical disability or psychosexual problem, and to couples using donor sperm because of azoospermia (no sperm in the ejaculate) when surgical sperm retrieval is not suitable or has failed.
• Donor insemination. Women, trans men and non-binary people with female reproductive organs who use donor insemination and have not conceived after 6 cycles should be offered further assessment, then 6 cycles of unstimulated donor IUI, if there is no known cause of infertility, before IVF is considered. NICE keeps its long-standing advice that donor sperm should be placed in the womb (IUI) rather than at the cervix, because it improves pregnancy rates.
• Miscarriage does not restart the clock. A new recommendation (1.16.7) says that a miscarriage or an ectopic pregnancy during the qualifying period, including during the 12 cycles of artificial insemination, should not restart that period.

Why NICE changed its view

NICE explains its reasoning in the guideline's rationale section (NICE, NG257 rationale and impact). The committee examined a network meta-analysis comparing no treatment, several ovarian stimulation regimens, IUI with or without stimulation, and IVF, measured on live births, clinical pregnancies and multiple pregnancies, together with an economic model built on it. It concluded that IVF remains the most cost-effective first-line treatment for unexplained infertility and that ovarian stimulation alone is neither effective nor cost-effective. There was, however, enough evidence that IUI with gonadotrophin stimulation could be cost-effective for it to be considered as an alternative first step, and the committee acknowledged that some people prefer a less invasive treatment.

The committee expected that more people might choose IUI first, with some rise in costs limited by the small share of people concerned and by the IVF cycles it would avoid for some of them.

IVF access after IUI

NG257 also rewrites the criteria for NHS-funded IVF, and IUI counts towards them. IVF is offered to those who have not reached their 42nd birthday if there is a diagnosed cause of infertility that other treatments cannot address, if they have unexplained infertility and have not conceived after two years, with or without IUI, or if they have not conceived after 12 cycles of artificial insemination, of which at least 6 were IUI. Under 40, an initial 3 full cycles are offered, and up to 3 further cycles may be considered. At 40 or 41, one full cycle is offered to people who have not had IVF before. The 2013 guideline had allowed one cycle up to the age of 42 under certain conditions; NICE found that the cost-effectiveness evidence did not support IVF at 42.

As before, NICE guidance tells the NHS what it should provide, but local integrated care boards decide how services are commissioned, and access has long varied from one area to another. Funded cycles and waiting times may therefore differ from the guideline for some time.

Questions to ask a clinic

• Is IUI appropriate in my situation, given my age, my tubal test results and the semen analysis?
• Will the cycle be unstimulated or stimulated, and if stimulated, how will follicles be monitored and when would a cycle be cancelled?
• How many cycles do you suggest before reconsidering, and how do they count towards NHS IVF criteria where I live?
• What are the clinic's own results for IUI in people of my age? The HFEA's clinic search lists licensed clinics that offer it.

Before any treatment, both partners are normally assessed. NICE offers that assessment after a year of trying without success, or sooner from the age of 36 or when a cause is suspected; what that one-year threshold means is explained in how common is infertility?.

This article summarises HFEA information and NICE guidance as published on the dates shown. It is not personal medical advice: the right treatment depends on individual tests and circumstances, which a GP or fertility specialist can assess.