IUI
What is IUI?
Intrauterine insemination (IUI) is a fertility treatment that involves placing prepared sperm directly into the uterus around the time of ovulation.
By placing sperm closer to the fallopian tubes, IUI reduces the distance sperm need to travel to reach the egg. Fertilisation still occurs naturally within the body.
IUI is a relatively simple and minimally invasive fertility treatment and is often recommended before progressing to more complex treatments such as in vitro fertilisation (IVF).
Who might benefit from IUI?
IUI may be recommended for couples or individuals where pregnancy has not occurred naturally despite appropriate investigations.
It may be considered in situations including:
- unexplained infertility
- mild male factor infertility
- ovulation disorders when combined with ovulation induction
- the use of donor sperm
- difficulties with sexual intercourse or ejaculation.
Before recommending IUI, your fertility specialist will assess both partners to determine whether this treatment is likely to provide a reasonable chance of pregnancy.
How does an IUI cycle work?
While every treatment plan is personalised, most IUI cycles follow the same general steps.
Step 1: Monitoring your cycle
The first goal is to identify when you are about to ovulate.
This may happen in one of two ways:
- Natural cycle IUI, where your body’s natural ovulation is monitored.
- Stimulated cycle IUI, where fertility medications encourage one or two eggs to mature.
Ultrasounds and blood tests are used to monitor follicle growth and determine the ideal timing.
Step 2: Triggering ovulation
Once a mature follicle is ready, your fertility specialist may recommend a trigger injection.
This helps predict exactly when ovulation will occur so the insemination can be timed as accurately as possible.
Timing is one of the most important factors in IUI success.
Step 3: Preparing the sperm
On the day of the procedure, a sperm sample is collected.
In the laboratory, the sample undergoes a process called sperm washing.
This separates healthy, highly motile sperm from seminal fluid and other cells, leaving a concentrated sample of the strongest swimmers.
Step 4: The insemination
The prepared sperm are placed into the uterus using a thin, flexible catheter.
The procedure usually takes only a few minutes.
Most women describe it as similar to a cervical screening test. It generally does not require sedation, and many people return to work or normal activities afterwards.
Some women notice mild cramping afterwards, but significant discomfort is uncommon.
What happens after IUI?
After insemination, the sperm continue their journey naturally through the reproductive tract towards the fallopian tubes, where fertilisation may occur if an egg is present.
You may be prescribed progesterone after treatment to support the uterine lining, depending on your individual treatment plan.
A pregnancy test is usually performed approximately two weeks after the procedure.
What are the chances of success?
The likelihood of pregnancy depends on many factors, including:
- your age
- the cause of infertility
- sperm quality
- whether fertility medication has been used
- the number of treatment cycles completed.
Pregnancy rates are generally highest in younger women and when infertility is related to ovulation disorders or mild male factor infertility.
Your fertility specialist will discuss your individual chance of success and the number of treatment cycles that may be appropriate before considering alternative treatments.
Is IUI painful?
This is one of the most common questions.
For most people, the answer is no.
The procedure may cause mild cramping or slight discomfort while the catheter passes through the cervix, but this usually lasts only a minute or two.
If you’ve previously had cervical screening, the experience is often very similar.
What are the risks?
IUI is considered a very safe procedure.
Potential risks include:
Multiple pregnancy
If ovulation induction medications are used, there is an increased chance of twins or higher-order multiple pregnancies.
Careful monitoring helps minimise this risk.
Ovarian hyperstimulation syndrome (OHSS)
OHSS is uncommon during IUI treatment but may occur when injectable fertility medications are used.
Regular monitoring significantly reduces this risk.
Infection
Infection following IUI is very uncommon because the sperm preparation process and insemination are performed using sterile techniques.
Medication side effects
If fertility medications are prescribed, temporary side effects may include:
- bloating
- headaches
- breast tenderness
- mood changes
- mild pelvic discomfort.
These symptoms usually resolve once treatment has finished.
Looking after yourself during treatment
Although IUI is less invasive than IVF, fertility treatment can still be emotionally demanding.
During treatment it is helpful to:
- attend all scheduled monitoring appointments
- take medications exactly as prescribed
- maintain a healthy lifestyle
- ask your fertility team about any concerns that arise during your treatment cycle.
Many people require more than one treatment cycle before achieving pregnancy.
When might IVF be recommended instead?
If pregnancy has not occurred after an appropriate number of IUI cycles, your fertility specialist may recommend progressing to IVF.
This recommendation is based on your individual circumstances, including your age, fertility diagnosis and response to treatment.
Moving to IVF does not mean IUI has failed. It simply reflects the treatment most likely to provide the best chance of pregnancy moving forward.
What to remember
IUI is a simple, minimally invasive fertility treatment that allows fertilisation to occur naturally within the body.
For appropriately selected patients, it can be an effective treatment before considering IVF. Your fertility specialist will recommend the treatment pathway that offers the greatest chance of success based on your individual circumstances.
Further Information
If you would like to learn more about fertility treatments, refer to the accompanying CHARLI information sheets on Ovulation Induction and In Vitro Fertilisation (IVF).
This article is intended for educational purposes only and should not replace personalised medical advice, diagnosis or treatment. Every article is written by a qualified specialist clinician and independently reviewed by a second specialist clinician to help ensure clinical accuracy and reflect current evidence-based practice.
