
Fertility and causes of infertility

In this section
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How age affects fertility
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How to improve male fertility
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Fertility treatment options
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What is IVF? The process, risks, success rates and more
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How does endometriosis affect fertility?
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PCOS and fertility: everything you need to know
Overview
What is fertility?
Fertility is the ability to get pregnant. The time it takes to get pregnant varies for everyone. Most women and birthing people get pregnant within a year of trying (age can make a difference here). Around 1 in 7 couples have difficulties getting pregnant.
Are you ready to conceive? Use our tool to find out.
Trying to get pregnant
More than 8 out of 10 couples where the woman is aged under 40 will get pregnant within one year if they have regular unprotected sex. More than 9 out of 10 couples will get pregnant within 2 years.
Regular, unprotected sex means having sex every 2 to 3 days without using contraception.
If you’re trying for a baby, you don't need to time having sex only around ovulation. Having vaginal sexual intercourse every 2 to 3 days will give you the best chance of getting pregnant.
Remember it’s important for you and your partner to try and keep sex enjoyable by concentrating on each other and your relationship, rather than worrying about conceiving. This will help you limit stress.
Find out more about how long it can take to get pregnant.
Contraception and getting pregnant
Most women and birthing people use contraception as a safe way to avoid getting pregnant when they are not ready for children. When you stop contraception, it is often because you would like to try for a baby.
If you have been taking contraception that uses hormones (such as the Pill, the patch, or injections) for a long time, you may not know your cycle very well (for example how long it is). This is because the bleed that can happen when you move to a new packet of the Pill is not a true period. A true period happens when you ovulate (release an egg from your ovaries) and the Pill prevents ovulation.
Read more about how pregnancy works.
If you’ve stopped taking hormonal contraceptives your periods may be irregular (come at different times of the month) for the first few months while your body gets used to the change in hormone levels.
Read more about stopping contraception.
The Pill does not cause infertility, but it may cover up conditions that are linked to infertility because not having periods can be a sign of ovulation problems, endometriosis or PCOS. If you do not have periods naturally, these problems may be missed until you come off contraception.
Causes for infertility or reduced fertility
- Ovulation problems
- Endometriosis
- Poor egg quality
- Polycystic ovarian syndrome (PCOS)
- Fallopian tube problems
- Unexplained infertility
- Poor sperm quality
- Age
- Premature menopause (premature ovarian insufficiency).
Asherman’s Syndrome
More research is needed into whether scar tissue in your womb could cause fertility problems. It’s possible that your fertility could be affected if you have a large amount of severe scar tissue from a lot of surgeries on your womb. Asherman's syndrome is a condition where scar tissue causes parts of the wall of your uterus to stick together. Symptoms include having period symptoms but no actual bleed 2-3 months after surgery. Contact your GP if you notice these symptoms.
What can affect fertility?
Sometimes there is no known reason for infertility. However, research shows there are several factors that can affect it.
These include:
- age – fertility declines with age
- weight – being overweight or obese (having a BMI of 30 or over) reduces fertility. In women, being overweight or severely underweight can affect ovulation
- having sexually transmitted infections (STIs) including chlamydia
- smoking (including passive smoking) affects your chance of conceiving and can reduce semen quality; read more about quitting smoking
- alcohol – the safest approach is not to drink alcohol at all to keep risks to your baby to a minimum if you do get pregnant. Drinking too much alcohol can also affect the quality of sperm (the chief medical officers for the UK recommend adults should drink no more than 14 units of alcohol a week, which should be spread evenly over 3 days or more)
- environmental factors – exposure to certain pesticides, solvents and metals has been shown to affect fertility, particularly in men
- stress can affect your relationship with your partner and cause a loss of sex drive. In severe cases, stress may also affect ovulation and sperm production.
When to get help with fertility
Infertility is only usually found out when you haven’t become pregnant within a year of regular unprotected sex. Make an appointment with your GP if you haven’t conceived after a year.
You should see your GP sooner if:
- you are over 36 (fertility deceases with age)
- you have a known fertility issue, such as endometriosis or polycystic ovary syndrome (PCOS)
- your partner (if you have one) has a known fertility issue, such as low sperm count
- you are concerned you or your partner may have a medical issue that may be affecting your ability to get pregnant
- you have irregular or no periods.
Your GP will ask you about your lifestyle, general health and medical history. They may ask you questions about:
- any previous pregnancies or children you may have
- how long you have been trying to conceive
- how often you have sex
- how long it has been since you stopped using contraception
- if you take any medication
- your lifestyle and habits.
They may also advise you about the things you can do to improve your chances of getting pregnant and how your partner (if you have one) can improve their fertility.
What is unexplained infertility?
Unexplained fertility is when no reason has been found for a person’s fertility problems. In this case you should not be offered any fertility drugs taken by mouth as this does not improve the chances of conceiving naturally.
If you have been trying to conceive naturally for more than two years (including the year before your fertility tests) you may be offered IVF or artificial insemination where sperm is placed the cervix (the neck of the womb) or the womb though this will depend on your NHS trust’s eligibility criteria.
Fertility tests
If you are having difficulty getting pregnant, you and your partner (if you have one) will both be offered fertility tests.
Tests for men and partners
Men should be offered a semen test to measure the quantity and quality of their sperm.
Tests for women and birthing people
Fertility tests for women and birthing people may include:
- blood tests to check your hormone levels
- tests (including blood tests and ultrasound scans) to see how well your ovaries may respond to fertility drugs
- an examination to see whether your fallopian tubes are blocked.
Fertility treatment
This will depend on what’s causing the fertility issues and what’s available in your local area.
There are three main types of fertility treatment:
- drugs to improve ovulation
- surgery if there are blockages or growths in the reproductive system
- assisted conception – including intrauterine insemination (IUI) and in vitro fertilisation (IVF).
Secondary infertility
Secondary infertility is when you have had 1 or more pregnancies in the past and are having difficulty conceiving again.
Many NHS trusts will not offer IVF if you (or your partner, if you have one) already have children but you should still speak to your GP. They can check for common causes of fertility problems and suggest treatments that could help.
Read more about treatment for infertility.
Support
We understand that having fertility issues can be hard to cope with both mentally and emotionally. Getting the right support can make all the difference. It’s a good idea to speak to your GP, friends and family to help support you through this time. The Fertility Network UK also has support and forums for those affected by infertility.
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Review dates
Last reviewed: 25 April 2025
Next review: 25 April 2028

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