IUI (Intrauterine Insemination)

Introduction

IUI, or intrauterine insemination, is one of the most widely used fertility treatments. It is often the first medical step couples and individuals take when natural conception has not happened after several months of trying, or when there is a specific reason — such as ovulation difficulty, mild sperm issues, or the need to use donor sperm — that makes timed insemination a sensible option.

If you are reading this, you have probably already had some fertility tests, spoken to a gynaecologist or fertility specialist, and been told that IUI may be worth considering. This guide walks through what IUI is, who it tends to help, how a typical IUI cycle unfolds from day one of the period through to the pregnancy test, what success rates look like in general terms, and how IUI compares with other paths such as IVF. It also covers the practical and emotional sides of going through one or more cycles.

IUI is a relatively simple, low-intervention treatment compared with IVF. That simplicity is one of its strengths, but it also means that the chance of pregnancy in any single cycle is modest. Understanding what to expect — clinically and emotionally — helps you make informed decisions with your fertility team.

What Is IUI?

IUI stands for intrauterine insemination. In an IUI procedure, a sample of sperm is prepared in the laboratory and then placed directly inside the uterus through a thin, soft catheter passed through the cervix. The aim is to put a higher concentration of motile (actively swimming) sperm closer to the fallopian tubes at the time of ovulation, shortening the distance the sperm need to travel to meet the egg.

Diagram showing sperm deposited directly into the uterus via a thin catheter, close to the fallopian tubes.

AI-generated illustration

IUI does not bypass the fallopian tubes or the natural fertilisation process. Fertilisation still has to happen inside the body, in the tube, in the same way as during natural conception. This is an important difference from IVF (in vitro fertilisation), where fertilisation happens in the laboratory.

The sperm used can come from a partner or from a sperm donor, depending on the clinical situation. The eggs are the patient’s own, released either in a natural menstrual cycle or in a cycle where mild medication has been given to help the ovaries produce one or two mature eggs.

IUI is sometimes also called artificial insemination, though strictly speaking artificial insemination is a broader term that includes other placements (such as into the cervix). When people today talk about “artificial insemination” in a clinic setting, they almost always mean IUI.

Who Is IUI For?

Doctors commonly consider IUI in several situations. The decision depends on the cause of subfertility, the duration of trying to conceive, the age of the female partner, the results of basic fertility tests, and personal preferences.

Mild male-factor infertility

If a semen analysis shows a mildly reduced sperm count, reduced motility, or slightly abnormal morphology, IUI can help by concentrating the most active sperm and placing them closer to the egg. IUI is generally not effective when sperm parameters are severely reduced; in those situations, doctors typically move to IVF with ICSI (intracytoplasmic sperm injection).

Unexplained infertility

When standard tests — ovulation assessment, tubal patency, semen analysis — come back normal but pregnancy has not occurred after a year or more of trying (or six months if the female partner is over 35), the diagnosis is unexplained infertility. Major guidelines, including those from ESHRE, describe IUI with ovarian stimulation as a reasonable option in this group before progressing to IVF.

Ovulation disorders

For people who do not ovulate regularly — for example, in polycystic ovary syndrome (PCOS) — medication is often used to induce ovulation. IUI may be combined with ovulation induction to time insemination precisely with the release of the egg.

Cervical factor

If cervical mucus is thick, scarred from previous procedures, or otherwise hostile to sperm, IUI bypasses the cervix entirely by placing sperm directly in the uterus.

Use of donor sperm

IUI is commonly used by single women, same-sex female couples, and couples where the male partner has no sperm in the ejaculate (azoospermia) or carries a serious genetic condition. Donor sperm from a regulated sperm bank is used, with screening for infectious diseases and genetic conditions in line with national rules.

Sexual or ejaculation difficulties

For couples who cannot have penetrative intercourse due to physical, psychological, or medical reasons — including some men with spinal cord injury or retrograde ejaculation — IUI offers a way to use a partner’s sperm without intercourse.

Mild endometriosis

In some cases of mild (stage I or II) endometriosis where the tubes are open, IUI with stimulation is offered before IVF, although evidence in this group is mixed.

When IUI is generally not suitable

IUI relies on at least one open and functional fallopian tube and on sperm being able to fertilise the egg naturally. IUI is generally not appropriate when:

• Both fallopian tubes are blocked or significantly damaged
• Severe male-factor infertility is present
• The female partner has advanced endometriosis distorting the pelvic anatomy
• The female partner is older (typically late 30s and beyond) and ovarian reserve is significantly reduced — in which case IVF may be discussed earlier

Whether IUI is a reasonable next step in your situation is a clinical decision that depends on the full picture of your test results and history.

Alternatives to Consider First (or Alongside)

Before starting IUI, it is worth understanding the alternatives, because each has different strengths.

Timed intercourse with ovulation tracking

For couples without a clear medical reason for subfertility and where the female partner is under 35, a few more months of timed intercourse with ovulation prediction kits or follicular tracking by ultrasound may be advised. This is the least medical option and avoids any procedural intervention.

Ovulation induction without IUI

For people with ovulation disorders such as PCOS, medication alone (commonly letrozole or clomifene citrate) to induce ovulation, combined with timed intercourse, is often tried first. IUI is added if this does not result in pregnancy after several cycles.

IVF (in vitro fertilisation)

IVF involves stimulating the ovaries to produce multiple eggs, retrieving them surgically, fertilising them in the laboratory, and transferring an embryo back into the uterus. IVF has higher success rates per cycle than IUI but is more involved, more demanding physically, and more expensive. For couples with blocked tubes, severe male-factor infertility, advanced female age, or repeated IUI failure, doctors commonly recommend moving to IVF rather than persisting with IUI.

Surgical options

For specific issues such as fibroids distorting the uterine cavity, endometrial polyps, or correctable tubal disease, surgery may be considered before fertility treatment.

The choice between these paths is not always either-or. Many fertility teams suggest a small number of IUI cycles first when the clinical picture is favourable, with a clear plan to move to IVF if pregnancy has not occurred. ESHRE and ASRM guidance both support time-limited use of IUI rather than open-ended repetition.

The IUI Cycle: Step by Step

An IUI cycle follows a clear sequence over roughly four weeks, starting on the first day of the menstrual period. The exact details depend on whether the cycle is “natural” (no fertility medication) or “stimulated” (with medication to encourage one or more follicles to develop).

Step 1: Initial consultation and tests

Before the cycle starts, the fertility team confirms that IUI is appropriate. This typically includes:

• Pelvic ultrasound to check the uterus and ovaries
• Tubal patency test — usually a hysterosalpingogram (HSG) or hysterosalpingo-contrast-sonography (HyCoSy) — to confirm at least one tube is open
• Hormone blood tests, including ovarian reserve markers such as AMH
• Semen analysis (for partner sperm) or selection of donor sperm
• Screening for infectious diseases such as HIV, hepatitis B and C, and syphilis, as required by law

Lifestyle factors are usually discussed too — folic acid supplementation, body weight, smoking, and alcohol — because these affect outcomes and overall pregnancy health.

Step 2: Choosing a natural or stimulated cycle

In a natural cycle IUI, no fertility medication is used. The clinic monitors your own cycle and times the insemination with your natural ovulation. Natural cycles are simpler and avoid the risk of multiple pregnancy from extra follicles, but the chance of pregnancy per cycle is generally lower.

In a stimulated cycle IUI, medication is used to encourage the ovaries to develop one or two mature follicles. The medications most commonly used are:

• Letrozole — an oral tablet, increasingly used first-line, particularly in women with PCOS
• Clomifene citrate — another oral option used for decades
• Gonadotrophin injections (FSH) — injectable hormones used when oral medications have not worked or when more precise control is needed; require close monitoring because of higher risk of multiple follicles

Major guidelines, including those from ESHRE for unexplained infertility, generally favour IUI with mild ovarian stimulation over natural cycle IUI when fertility medication is not contraindicated, because pregnancy rates per cycle are higher. The trade-off is a higher chance of multiple pregnancy (twins or more), particularly with injectable gonadotrophins.

Step 3: Monitoring follicle growth

Starting around day 2 or 3 of the period, medication (if used) is begun. From around day 8 or 9, transvaginal ultrasound scans are used to track the growing follicles — the fluid-filled sacs in the ovary that each contain an egg. Blood tests for oestradiol and sometimes LH may be added.

Transvaginal ultrasound image showing a mature follicle developing within the ovary during an IUI cycle.

AI-generated illustration

The team is looking for a follicle that reaches about 17 to 20 mm in diameter, with an endometrial lining of around 7 mm or more. Most patients have two or three monitoring scans during a cycle.

If too many follicles develop — usually three or more mature follicles — the clinic may discuss either cancelling the cycle, converting to IVF (if facilities allow), or reducing the medication in future cycles to lower the risk of high-order multiple pregnancy.

Step 4: The trigger injection

Once a lead follicle is mature, a “trigger” injection of human chorionic gonadotrophin (hCG) is given to make the follicle release its egg about 36 hours later. Some natural cycle protocols rely on detecting the body’s own LH surge with urine tests or blood tests instead of using a trigger injection.

The timing of the trigger sets the timing of the IUI itself, which is usually scheduled for the following day or the day after.

Step 5: Sperm preparation

On the day of the IUI, the sperm sample is provided (or thawed if donor or frozen sperm). It then goes through a laboratory process called sperm washing or sperm preparation. This separates motile sperm from the seminal fluid, dead cells, and other debris. The seminal fluid is removed because it contains prostaglandins that could cause painful uterine cramping if placed directly inside the uterus.

Common preparation methods include density gradient centrifugation and swim-up. The final sample is a small volume of concentrated, motile sperm in a culture medium, ready for insemination.

Laboratory technician processing a sperm sample using density gradient centrifugation to isolate motile sperm.

AI-generated illustration

Step 6: The insemination procedure

The IUI procedure itself is quick — usually under ten minutes — and takes place in the clinic. You lie down as if having a routine pelvic exam. A speculum is inserted into the vagina to see the cervix, which is then cleaned. A thin, soft catheter loaded with the prepared sperm is passed through the cervix into the uterus, and the sperm is gently injected.

Patient resting comfortably on a clinical examination table during a routine IUI insemination appointment.

AI-generated illustration

Most people describe the experience as similar to a cervical smear — some pressure or mild cramping, but generally not painful. No anaesthetic is needed. After the procedure, many clinics ask you to lie down for 10 to 15 minutes, although the evidence that this changes outcomes is limited.

You can usually return to normal activities the same day. Light spotting after the procedure is common and not a cause for concern. Some clinics perform a single insemination per cycle; others do two over consecutive days. Current evidence does not clearly favour double over single insemination for most patients.

Step 7: The luteal phase and pregnancy test

After IUI, the two-week wait begins — the period between insemination and the pregnancy test. Some clinics prescribe progesterone supplementation (vaginal pessaries, gel, or oral tablets) during this phase to support the lining of the uterus, particularly after stimulated cycles. Others reserve progesterone for specific situations.

A blood pregnancy test (beta-hCG) is typically scheduled around 14 days after the IUI. Home urine pregnancy tests can give early but sometimes misleading results; the clinic blood test is more accurate. If the test is positive, an ultrasound scan a couple of weeks later confirms the pregnancy and checks the number of sacs.

If the test is negative, the period usually starts within a few days. The clinic will arrange a review to discuss whether to try another IUI cycle, adjust the protocol, or move to a different treatment.

Variations and Additions

Several variations are used depending on the situation.

Donor sperm IUI

When donor sperm is used — for single women, same-sex female couples, or couples with severe male-factor infertility — sperm is selected from a regulated sperm bank, with full screening for infectious diseases and genetic conditions. The IUI procedure itself is identical; the sperm has been frozen and is thawed on the day of insemination. Frozen donor sperm has slightly lower motility than fresh sperm but is widely and successfully used.

IUI with frozen partner sperm

If the male partner cannot be present on the day of IUI, or has previously banked sperm before a cancer treatment or other medical procedure, frozen sperm can be thawed and used in the same way as donor sperm.

Surgical sperm retrieval and IUI

For men with very low sperm counts or obstruction, sperm can sometimes be retrieved surgically. However, the very small numbers of sperm obtained in such procedures are usually too few for IUI, and these samples are more commonly used with IVF and ICSI.

Number of cycles

If pregnancy has not occurred after a defined number of properly conducted IUI cycles — commonly three to six, depending on the clinical situation and the female partner’s age — major fertility societies suggest reviewing the plan and considering IVF. Persisting with IUI beyond this point produces diminishing returns.

Success Rates

Illustration of rising cumulative pregnancy probability across three to four successive IUI treatment cycles.

AI-generated illustration

Success rates with IUI vary widely depending on the underlying cause of subfertility, the female partner’s age, the sperm parameters, whether stimulation is used, and the number of cycles undertaken. Rather than quote a single number, it is more accurate to describe the patterns clinicians see.

• Per-cycle pregnancy rate in a favourable case — younger woman, mild male-factor or unexplained infertility, stimulated cycle — is generally in the range of 10 to 15 percent.
• Cumulative pregnancy rate rises with each successive cycle. Most pregnancies from IUI occur within the first three to four cycles.
• Age is a major factor. Success rates decline noticeably from the mid-30s, more steeply through the late 30s, and are markedly lower after 40. For women over 40, many fertility teams discuss moving directly to IVF.
• Stimulated cycles tend to give higher per-cycle pregnancy rates than natural cycles, at the cost of a higher chance of multiple pregnancy.
• Severe male-factor infertility, advanced female age, very low ovarian reserve, and tubal disease all reduce IUI success.

Your fertility specialist can give you a more personalised estimate based on your specific test results and history. National registry data for IUI outcomes in India is limited, so individual clinic discussions are the most reliable source of guidance for your situation.

Risks and Complications

IUI is generally a safe procedure with a low complication rate. The main risks come from the fertility medications used in stimulated cycles, not the insemination itself.

Multiple pregnancy

The most clinically important risk of stimulated IUI is multiple pregnancy — twins, and less commonly triplets or higher. Multiple pregnancies carry significantly higher risks for both mother and babies, including preterm birth, low birth weight, pre-eclampsia, and gestational diabetes.

The risk depends on the medication used. With letrozole or clomifene, the twin rate is typically around 5 to 10 percent; with injectable gonadotrophins, it can be considerably higher unless dosing is conservative and monitoring is strict. Most clinics will cancel or convert a cycle to IVF if three or more mature follicles develop.

Ovarian hyperstimulation syndrome (OHSS)

OHSS is an exaggerated response to fertility medication in which the ovaries become enlarged and fluid accumulates in the abdomen. Severe OHSS is rare with IUI cycles because the doses used are much lower than in IVF, but mild forms can occur, particularly with injectable gonadotrophins. Symptoms include abdominal bloating, pain, and nausea. You should contact your clinic urgently if you develop significant abdominal pain, breathlessness, severe vomiting, or reduced urination.

Infection

Pelvic infection after IUI is uncommon — reported rates are well below 1 percent — because the sperm is washed and a sterile catheter is used. Persistent pelvic pain, fever, or unusual vaginal discharge after IUI should be reported promptly.

Cramping and spotting

Mild cramping during or after the procedure and light spotting are common and settle quickly. They are not a sign of failed treatment or harm.

Ectopic pregnancy

As with any pregnancy in someone with fertility issues, the risk of ectopic pregnancy — where the embryo implants outside the uterus, most often in a fallopian tube — is slightly higher than in the general population. Early ultrasound after a positive pregnancy test confirms the location of the pregnancy.

Emotional risk

The emotional impact of fertility treatment is not a minor side issue. A negative pregnancy test, particularly after several cycles, can be very difficult. Fertility societies increasingly recognise psychological support as a core part of fertility care rather than an optional add-on.

Emotional and Practical Considerations

Going through IUI is medically straightforward but emotionally demanding. A few things tend to help.

Plan a small number of cycles, then reassess

Going into treatment with an open-ended “we’ll just keep trying” mindset is often harder than agreeing in advance with your team how many cycles you will try before reviewing. Three to four cycles is a common framework for younger patients with favourable conditions; fewer for older patients or those with reduced ovarian reserve.

Decide together what comes next

Talking through — before starting — what you will do if IUI is unsuccessful (move to IVF, take a break, consider donor sperm or donor egg, stop treatment) reduces the pressure of having to make that decision in the disappointment of a negative result.

Manage the two-week wait

The wait between IUI and the pregnancy test is one of the harder parts of the cycle. Normal exercise, work, and daily life are safe and encouraged. Symptoms during this time — breast tenderness, mild cramping, mood changes — can come from progesterone (whether natural or supplemented) and do not reliably predict the result. Home pregnancy tests before the scheduled blood test often add stress without giving reliable answers.

Support and counselling

Many fertility clinics offer access to counsellors with specific training in fertility care. Peer support groups, both in-person and online, can help reduce the sense of isolation that fertility treatment often brings. Your partner, if you have one, is going through this with you in their own way; communication that allows both of you to express disappointment, hope, and fear tends to protect the relationship across treatment.

Lifestyle

Sensible lifestyle measures — not smoking, limiting alcohol, healthy body weight, taking folic acid — support outcomes and overall pregnancy health. Extreme dietary or exercise changes are not necessary and may add stress.

When to Move from IUI to IVF

One of the more important decisions in fertility care is when to stop persisting with IUI and move to IVF. There is no single right answer, but doctors commonly use the following pointers.

• Three to six properly conducted IUI cycles without pregnancy is generally the upper limit before reviewing the plan.
• If new information emerges — for example, a second semen analysis showing worse results, or evidence of tubal disease — the conversation about IVF may happen sooner.
• For women in their late 30s, the threshold to move to IVF is lower, because time matters more.
• If ovarian reserve testing suggests a limited window, fertility teams typically recommend not spending too many months on lower-yield treatments.

The decision belongs to you and your specialist together. It is reasonable to ask, at the start of treatment, what the clinic’s suggested plan is if IUI does not work.

Frequently Asked Questions

Is IUI painful?

Most people experience IUI as mildly uncomfortable rather than painful. The sensation is similar to a cervical smear: some pressure as the speculum is placed and a brief cramp as the catheter passes through the cervix. The procedure itself takes only a few minutes and does not require anaesthesia. If you have a history of difficult pelvic exams or known cervical narrowing, tell your clinic in advance so they can plan accordingly.

How long after IUI can I take a pregnancy test?

A blood pregnancy test (beta-hCG) is usually most accurate around 14 days after the IUI. Home urine tests done earlier than this often give false negatives, and false positives are possible if a trigger injection of hCG was used (the hCG from the injection can linger in the body for around 10 to 14 days). Following the timing your clinic recommends gives the most reliable result.

Can I exercise, work, or travel after IUI?

Yes. Normal activities — including work, light exercise, and travel — are generally fine after IUI. There is no evidence that lying flat for hours, avoiding stairs, or avoiding exercise improves the chances of pregnancy. Heavy lifting or extreme exertion is best avoided in the first day or two if you have any cramping, but otherwise life continues as normal.

How many IUI cycles should I try before considering IVF?

Most fertility societies suggest that the majority of IUI pregnancies happen within the first three to four cycles. After three to six unsuccessful cycles, doctors typically recommend reviewing the approach and discussing IVF. This number may be lower if the female partner is older or has reduced ovarian reserve.

Is there an age limit for IUI?

Biologically, the chance of pregnancy with IUI declines steeply through the late 30s and is markedly lower after 40. In India, the Assisted Reproductive Technology (Regulation) Act 2021 also sets legal age limits for assisted reproductive treatments — up to 50 years for the female partner and 55 years for the male partner. In practice, many fertility teams discuss moving directly to IVF rather than IUI for women in their early 40s, because IVF gives a better chance of success in a shorter time.

Will IUI increase my chance of having twins?

IUI itself does not increase the chance of twins — the medication used in stimulated cycles does. With oral medication such as letrozole or clomifene, the twin rate is typically around 5 to 10 percent. With injectable gonadotrophins, the risk is higher unless monitoring is careful. Triplets and higher-order multiples are rare with conservative protocols. Your clinic will discuss steps to limit multiple pregnancy risk before each cycle.

Does IUI work for severe male-factor infertility?

Generally, no. IUI relies on having enough motile sperm after washing to give a reasonable chance of fertilisation. When sperm count or motility is severely reduced, IVF with ICSI — where a single sperm is injected directly into each egg in the laboratory — gives much better results. Your fertility team will review your semen analysis before deciding whether IUI is worth trying.

Can IUI be done in a natural cycle without medication?

Yes. Natural cycle IUI is an option for people who cannot or prefer not to take fertility medication, for some same-sex couples and single women with no underlying fertility issue, or where the goal is simply to use donor sperm. Per-cycle success rates are lower than in stimulated cycles, but the approach avoids the risks of medication and multiple pregnancy.

What if I have only one fallopian tube?

IUI can still work with one open tube, provided the tube is functional and the ovary on that side (or sometimes the opposite side) releases an egg. Some clinics use ultrasound monitoring to confirm that follicle growth is happening on the side with the open tube, particularly in natural cycles.

Does IUI cause cancer or other long-term problems?

Large studies of fertility medications used in IUI — clomifene, letrozole, and gonadotrophins — have not shown a clear increase in long-term cancer risk. Short-term risks (OHSS, multiple pregnancy) are well-defined and minimised by appropriate monitoring. As with any treatment, your fertility specialist can discuss risks specific to your medical history.

Conclusion

IUI is a relatively simple, low-intervention step in fertility care. It tends to be most useful in well-defined situations — mild male-factor infertility, unexplained infertility, ovulation disorders, donor-sperm cycles, and certain cervical or sexual issues — and in patients where time and ovarian reserve allow for a few cycles before considering more intensive treatment.

Understanding the cycle in advance, agreeing on a clear plan with your fertility specialist for how many cycles to try and what comes next, and giving yourself permission to take breaks and seek emotional support all help to make the experience more manageable. Whether IUI is the right next step for your situation, and how it fits into a broader fertility plan, is a decision best made together with a specialist who knows your full clinical picture.