Medical Conditions > Unexplained infertility
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Unexplained infertility

All you need to know

What is unexplained infertility?

It can be really frustrating if you’re struggling to conceive, but doctors don’t know why. This is called unexplained infertility, and it accounts for about one in four cases of infertility in the UK, according to the NHS. 

Infertility is when you’ve been trying to get pregnant for at least one year if the woman carrying the baby is younger than 35 or six months if she is 35 or older. Typically, fertility testing will tell you why you’re having trouble getting pregnant — but with unexplained infertility, those medical checks and tests come back normal.

Getting diagnosed with unexplained infertility can be very disappointing and might leave you with more questions than answers. However, iIt’s important to know thatknow, however, that it doesn’t mean you can never have a child. Many people individuals and couples with unexplained infertility successfully start a family. Some figures show that 21-50% of couples diagnosed with unexplained infertility successfully conceive.

Keep reading to learn what an unexplained infertility diagnosis means and what fertility treatments are available. 

What are the causes of unexplained infertility?

Unexplained infertility means there’s no identifiable cause why a person or couple can’t get pregnant. There is a reason why they’re struggling to conceive, but doctors just don’t know what it is. 

Infertility can be caused by many things affecting both men and women. It can be due to problems with ovulation, sperm quality, or issues with the reproductive organs (such as endometriosis or a blocked fallopian tube). With unexplained infertility, however, all the tests show you’re perfectly healthy, and everything works as it should. 

The frustrating reality is that doctors aren’t always able to pinpoint why someone is having difficulty getting pregnant. There could be an underlying undiagnosed condition or a factor unknown to doctors. Researchers are constantly learning more about how different conditions can affect fertility, but there's still a lot that medical professionals don't know at this time.

How is unexplained infertility diagnosed?

Unexplained infertility is a diagnosis of exclusion, which means your doctor will first check that you don’t have any conditions known to affect fertility. 

You should see your GP if you’ve been trying to get pregnant for a year (or six months if you’re over 35) with no success. They will ask about your medical and sexual history and depending on the guidelines for your practice, they’ll run some fertility tests

GP’s tend to offer the following fertility tests for women:

  • Blood tests to look at hormone levels including FSH, LH and progesterone

  • Blood tests to check your thyroid levels 

  • Testing for sexually transmitted infections (STIs) such as chlamydia or rubella 

Depending on these results, you may be referred for additional tests including:

  • A physical exam and ultrasound to check the ovaries, womb, and fallopian tubes

  • AMH blood test to check your ovarian reserve (how many eggs you have)

Fertility tests for men include: 

  • A physical exam to check the testicles and penis 

  • Semen analysis to check for any problems with sperm count or quality

  • Testing for sexually transmitted infections (STIs) such as chlamydia.

Your GP will run these tests depending on whether or not you meet the criteria, such as your age and how long you’ve been trying to conceive. Whether or not you’re eligible can also depend on where you live in the UK. Depending on the results, you may be referred to a fertility specialist. 

You’ll be diagnosed with unexplained infertility if all these tests come back normal and your doctor can’t find a cause. It’s understandable to feel helpless or frustrated at this point, but the good news is that fertility treatments are available. It's important to have a healthcare provider who understands what you're going through and is there to support you

What are the treatments for unexplained infertility?

The most common treatments for unexplained infertility fall under assisted reproductive technologies (ART). This type of fertility treatment is where part of the fertilisation process happens in a lab or is facilitated by a clinician. ART treatments include:

Intrauterine Insemination (IUI)

Intrauterine insemination (IUI) is a fertility treatment where sperm is directly injected into the uterus. It can be done during a natural ovulation cycle or with the help of hormone therapy. It's a great option for those who want a less invasive alternative to IVF and can be done using donor sperm. That said, the National Institute for Health and Care Excellence (NICE) — which provides evidence-based guidance for clinical care in the UK — doesn’t recommend IUI in the case of unexplained fertility, as it hasn’t been shown to help.

In vitro fertilisation (IVF)

In vitro fertilisation (IVF) is a medical procedure that involves combining eggs and sperm in a lab dish to create fertilised embryos. The fertilised embryos can then be placed in the woman's uterus to grow and develop, and any extra embryos can be preserved for future use. The NICE recommends IVF for anyone with unexplained infertility who has been trying to conceive naturally (through unprotected sex) for two years — including one year of trying before fertility tests.

Intracytoplasmic sperm injection (ICSI)

Intracytoplasmic sperm injection (ICSI) involves injecting sperm directly into the egg. ICSI is an add-on treatment to IVF (not a stand-alone one), and it can increase your chances of getting pregnant in cases where you have already tried IVF but didn't experience fertilisation.

Donor eggs or sperm

If you’re struggling with unexplained infertility, you can use donor eggs, sperm (also known as donor insemination), or embryos. Using a donor can be especially helpful for single people or female same-sex couples struggling to conceive for no identifiable reason.

What about medications?

While medications that stimulate ovulation — such as clomifene (Clomid), letrozole, and gonadotropins — can be helpful when there is a problem with ovulation, they’re not recommended for unexplained infertility. This is because, with unexplained infertility, there is no identified issue with ovulation, so they won’t increase your chances of getting pregnant.

Is it possible to prevent unexplained infertility?

You can’t prevent unexplained infertility because, without an identifiable cause, prevention is pretty much impossible. There are, however, some factors within your control that can help your chances of conceiving. Some lifestyle factors linked to poor fertility include: 

  • Drinking too much caffeine 

  • Taking recreational drugs

  • Smoking

  • Untreated STIs

  • Excessive alcohol consumption 

  • Being overweight or underweight.

We know it can feel like a shot in the dark, and while there’s no evidence that making lifestyle changes can increase your chances of conception, looking after your overall health, nutrition, and lifestyle certainly can't hurt!

​​Dealing with unexplained infertility can leave you feeling disheartened and lost.

Despite the lack of a clear diagnosis, options are still available to you. Remember, not knowing the cause of your infertility doesn't mean you won't be able to have a baby — nor does it mean your diagnosis should be dismissed just because “there’s nothing wrong with you”.

FAQs about unexplained infertility

Is it possible to get pregnant with unexplained infertility?

Yes, getting pregnant is possible even if you're diagnosed with unexplained infertility. It’s hard to know what your chances are of getting pregnant, but in one study of 4,999 couples with a diagnosis of unexplained infertility, 21% conceived naturally. Other research found that 50% of couples with unexplained infertility will conceive within a year, and another 12% in the year after. A diagnosis of unexplained infertility doesn't mean you have to give up your dreams of a baby. 

How many couples have unexplained infertility?

Figures vary, but according to the NHS, unexplained infertility accounts for one in four infertility cases in the UK. Other research shows that it affects 30% of couples worldwide.

How long should I try to get pregnant before contacting my GP?

You should speak to your GP if you’re under 35 and have been trying to conceive (having unprotected sex while ovulating) for over a year or six months if you’re 35 or older. 

Can I get treatment on the NHS for unexplained infertility?

Yes, but it can be difficult to know where to begin when it comes to fertility treatment eligibility criteria in the UK. It depends a lot on where you live, which is why fertility treatment is often referred to as a "postcode lottery". To get started, it's best to talk to your GP or reach out to your local integrated care board (ICB). They can give you all the information you need about NHS-funded treatment in your area and offer guidance on eligibility.

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