Being told you have unexplained infertility can leave you with more questions than answers.

It’s incredibly frustrating and upsetting when you’ve had all the tests and nothing has been found but you’re still struggling to fall pregnant.

If you've been diagnosed with unexplained infertility, IUI or IVF could help improve your chances of conceiving.

Here, BCRM's medical director, Dr Amanda Jefferys, explains how the two treatments work and what could help you decide which is right for you.

IUI or IVF for unexplained infertility at a glance

• What is unexplained infertility? It's when fertility tests haven't found a clear reason why pregnancy hasn't happened, even though you're still struggling to conceive.
• How does IUI help with unexplained infertility? Prepared sperm is placed directly into the womb prior to ovulation. It's less invasive than IVF and could be a good first step for some people.
• What's the difference between natural IUI and stimulated IUI? Natural IUI follows your own ovulation, while stimulated IUI uses medication to encourage the development of eggs.
• How is IVF different? Eggs are collected and fertilised in the laboratory, allowing the embryology team to observe fertilisation and early embryo development.
• Is IVF more successful than IUI? IVF generally has a higher chance of pregnancy per cycle, although the best option depends on your circumstances.
• Do you have to try IUI before IVF? No. Current NICE guidance supports discussing either IVF or stimulated IUI for eligible people with unexplained infertility.
• What should you think about when choosing between IUI and IVF? Your treatment history, the chances of success and how you feel about each treatment can all influence your decision.

What is unexplained infertility?

Unexplained infertility is when fertility tests haven’t found a clear reason why pregnancy hasn’t happened.

You might be ovulating regularly, your fallopian tubes could be open and a semen analysis might not show anything significant, but you’re still having difficulty conceiving.

That uncertainty can be difficult to sit with, especially when you’re hoping for answers about why pregnancy hasn’t happened.

The good news is that there are still treatment options available. IUI and IVF can both help improve your chances of conceiving, but they work in different ways.

How does IUI help with unexplained infertility?

IUI, or intrauterine insemination, helps the best of the sperm get closer to the egg.

A sperm sample is prepared in the laboratory to concentrate the most active sperm. It’s then placed directly into the womb around the time of ovulation using a thin catheter.

Fertilisation still happens inside your body, so the sperm needs to reach the egg naturally after insemination.

At least one fallopian tube needs to be open for IUI to work, so we might recommend a tubal test before treatment to check whether it's a suitable option for you.

One of the main reasons people consider IUI is that it’s a gentler treatment than IVF.

There’s no egg collection and fertilisation doesn’t take place in the laboratory. The insemination itself is a quick procedure and most people can go home shortly afterwards.

If you have unexplained infertility, IUI could help sperm reach the egg without having to move straight to IVF.

What’s the difference between natural IUI and stimulated IUI?

At BCRM, IUI can be done in two ways.

A natural IUI cycle follows your own ovulation. Ultrasound scans are used to track your cycle so insemination can be timed at the right point.

A stimulated IUI cycle uses fertility medication to encourage the development of one or two eggs. Your response is monitored with scans and treatment is timed around ovulation.

How is IVF different?

IVF takes fertilisation out of the body and into the laboratory.

You’ll take fertility medication to encourage several eggs to develop. These are monitored with ultrasound scans before being collected from the ovaries.

The eggs and sperm are then brought together in BCRM’s laboratory. If fertilisation takes place, the embryos are given time to develop before an embryo is transferred to the uterus.

One of the differences with IVF is that it can sometimes give us more information about why you’re having difficulty conceiving.

Because fertilisation happens in the laboratory, the embryology team can see how many eggs have been collected, whether they fertilise and how any embryos develop over the following days.

IVF won’t always uncover a reason for unexplained infertility. But it can help us understand more about what happens after the egg and sperm meet.

Is IVF more successful than IUI?

IVF generally offers a higher chance of pregnancy per treatment cycle than IUI, but success rates aren’t the only thing to think about.

IUI is less invasive because there’s no egg collection, while IVF involves ovarian stimulation, egg collection, laboratory fertilisation and embryo transfer. That difference can matter when you’re deciding what feels manageable.

Your age has a big influence on fertility treatment success, so general success rates won’t tell you exactly what your own chances will be. It’s also worth checking whether success rates refer to pregnancies or live births, as these figures can be different.

IVF could be worth considering sooner if you’ve already tried IUI without success or if there are other factors that make IUI less suitable.

For example, if both fallopian tubes are blocked, IVF can bypass them because fertilisation takes place in the laboratory.

Do you have to try IUI before IVF?

No, you don’t have to try IUI before IVF.

For people with unexplained infertility who’ve been trying to conceive through regular unprotected intercourse for two years, current NICE guidance recommends discussing either IVF or up to four cycles of stimulated IUI using gonadotrophin medication before moving on to IVF.

This means you don’t necessarily have to spend time trying IUI before considering IVF. We can talk through the benefits of each approach and help you understand what treatment could involve.

What should you think about when choosing between IUI and IVF?

If both treatments could be suitable, there are a few things worth thinking about:

• How long you’ve already been trying to conceive
• Your age and fertility test results
• Whether you’d prefer to start with a less invasive treatment
• How you feel about IVF medication and egg collection
• How many IUI cycles you’d feel comfortable trying before moving on
• Whether treatment is NHS-funded or you’re paying privately

You might feel more comfortable starting with IUI, or you might prefer to move straight to IVF because it generally offers a higher chance of pregnancy per cycle.

At BCRM, we’ll talk you through the options and give you the information you need to make a decision you feel comfortable with.

So, is IUI or IVF better for unexplained infertility?

There isn’t one treatment that’s better for everybody with unexplained infertility.

IUI could be a good first step if your fallopian tubes are open, there aren’t any more complex fertility problems and you’d prefer to start with a simpler treatment.

IVF could make more sense if you’ve already tried IUI or if there are reasons why moving straight to IVF could offer a better chance of success.

At BCRM, our doctors, specialist nurses and fertility scientists work together to help you understand your options and support you throughout treatment.

If you’ve been diagnosed with unexplained infertility and you’re not sure whether IUI or IVF could be the right next step, get in touch with us to talk through your options or meet our team at our next free open evening.