How Intrauterine Insemination Works: Success Rates, Costs and What to Expect in the UK

Intrauterine insemination is a fertility treatment in which washed, concentrated sperm is placed directly into the uterus through a thin catheter during ovulation. It is one of the least invasive and most affordable assisted conception procedures available in the UK. The HFEA reports that IUI success rates are generally around a third of IVF, but the procedure is significantly cheaper, quicker and less physically demanding. For single women, lesbian couples and heterosexual partners dealing with mild male factor infertility, IUI is often the recommended first-line treatment before considering IVF.

What Is Intrauterine Insemination and How Does It Work?

IUI works by shortening the journey sperm must travel to reach the egg. In natural conception, sperm travels from the vagina through the cervix, into the uterus and along the fallopian tubes — a journey that only about 5% of sperm survive. During IUI, a fertility specialist uses a thin catheter to place a concentrated sample of the healthiest, most motile sperm directly into the uterus, bypassing the cervix entirely. This brings the sperm much closer to the fallopian tubes where fertilisation occurs.

The procedure itself takes only a few minutes and is usually painless, similar to a cervical smear test. You may be asked to lie still for 10 to 15 minutes afterwards. The entire appointment, including preparation, typically lasts under an hour. Intrauterine insemination is timed to coincide with ovulation — either your natural cycle or a cycle stimulated with fertility medication — to maximise the chance of sperm meeting the egg at the right moment.

Who Should Consider Intrauterine Insemination?

Your doctor may recommend intrauterine insemination if you are dealing with one or more of the following situations: unexplained infertility after 12 months of trying, mild male factor infertility (low sperm count or reduced motility), hostile cervical mucus that prevents sperm from reaching the uterus, ejaculation dysfunction, a semen allergy, or if you are using donor sperm from a bank or a known donor.

Intrauterine insemination is particularly popular among single women and same-sex female couples who need donor sperm to conceive. It is also used by heterosexual couples where the male partner has borderline sperm quality that is unlikely to succeed through natural conception alone. On CoParents.co.uk, a co-parenting and sperm donation platform with over 150,000 users since 2008, many users connect with known donors and then proceed to IUI at a licensed clinic to ensure both medical safety and legal clarity.

What Is the Difference Between Intrauterine Insemination and IVF?

The key difference is where fertilisation takes place. During IUI, sperm is placed in the uterus and fertilisation happens naturally inside the fallopian tube. During IVF, eggs are collected from the ovaries, fertilised with sperm in a laboratory and the resulting embryo is transferred back into the uterus. IVF involves more steps, more medication and significantly higher costs, but it also offers higher success rates per cycle.

A single IUI cycle privately costs between £800 and £1,500 in the UK, while IVF ranges from £4,000 to £8,000. IUI requires less monitoring, fewer clinic visits and no egg retrieval procedure. For many patients, doctors recommend trying 3 to 6 cycles of intrauterine insemination before moving to IVF if conception has not occurred. This stepped approach balances cost, invasiveness and effectiveness.

How Should You Prepare for Intrauterine Insemination?

Preparation begins with a full assessment of your reproductive health. This typically includes blood tests to check hormone levels, an ultrasound scan to assess the uterus and ovaries, and a semen analysis to evaluate sperm count, motility and morphology. If you are using donor sperm, the clinic will confirm the sample meets quality standards.

Your doctor may prescribe fertility medication — such as Clomid (clomiphene) or injectable gonadotropins — to stimulate your ovaries to produce one or more eggs. Ultrasound scans monitor follicle development, and ovulation may be triggered with an injection of human chorionic gonadotropin when a follicle reaches the right size. Timing is critical for the procedure: the procedure is performed within 24 to 36 hours of the trigger injection or your natural LH surge.

On the day, your partner or donor provides a fresh semen sample, or a frozen sample is thawed. The lab washes the sperm to separate the fastest, healthiest swimmers from the rest. This concentrated sample is then drawn into a syringe attached to a thin catheter and gently inserted through the cervix into the uterus. The NHS recommends taking 400 micrograms of folic acid daily throughout the process, and maintaining a healthy lifestyle with balanced nutrition, limited alcohol and no smoking to optimise your chances.

What Are the Success Rates for Intrauterine Insemination?

Success rates for intrauterine insemination depend on age, the underlying cause of infertility, whether fertility medication is used and the quality of the sperm. The HFEA reports that IUI success rates are generally around a third of IVF rates. For women under 35 using donor sperm, the national average is approximately 15 to 20% per cycle. Success rates decline with age: women aged 35 to 39 have lower per-cycle rates, and the procedure is less commonly recommended for women over 42.

Cumulative success improves with repeated attempts. A 2015 study of over 1,800 women found that after six cycles of ICI (intracervical insemination, the home equivalent), the cumulative pregnancy rate was around 38%. IUI typically outperforms ICI because the sperm is placed directly inside the uterus. If you have not conceived after 3 to 6 cycles of intrauterine insemination, your fertility specialist will usually recommend moving to IVF, which offers success rates of around 31% per fresh embryo transfer nationally.

What Are the Risks of Intrauterine Insemination?

Intrauterine insemination is a low-risk procedure. The most common side effects are mild cramping or spotting after the catheter is inserted, which usually resolves within a day. In rare cases, a minor infection can occur, but this is easily treated with antibiotics. If you use fertility medication to stimulate ovulation, there is a small risk of ovarian hyperstimulation syndrome and a higher chance of multiple pregnancy (twins or triplets). Your clinic will monitor follicle development carefully and may cancel the cycle if too many eggs are developing, to reduce this risk.

Frequently Asked Questions

How many cycles of intrauterine insemination should I try before moving to IVF?

Most fertility specialists recommend 3 to 6 cycles. If you have not conceived after this number of well-timed attempts, the likelihood of success with further IUI cycles diminishes. Your doctor will review your results and may suggest IVF as a more effective next step, particularly if you are over 35 or have additional fertility factors.

Can I have intrauterine insemination on the NHS?

NHS funding for IUI varies by region. NICE guidelines recommend unstimulated IUI for single women and same-sex couples using donor sperm, and some Integrated Care Boards fund up to 6 cycles. Eligibility criteria differ across the country — your GP can advise on what is available in your area. If NHS funding is not available, private IUI treatment is widely accessible.

Is intrauterine insemination painful?

Most women describe the procedure as mildly uncomfortable rather than painful — similar to a cervical smear. The catheter insertion takes only a few minutes. Some women experience light cramping afterwards, but this typically passes quickly. No anaesthesia is required and you can return to normal activities the same day.

Can I use a known donor for intrauterine insemination at a clinic?

Yes. If you bring a known donor — found through personal networks or a platform like CoParents.co.uk — to an HFEA-licensed clinic, the donor undergoes the same screening and quarantine process as anonymous bank donors. Using a clinic for intrauterine insemination ensures the donor has no legal parental rights, which provides the strongest legal protection for you and your child.