Understanding fertility & infertility

Hormones are chemicals in your body that control many different processes, including reproduction. If there’s an imbalance in hormones, it can make getting pregnant harder.

Conditions like Polycystic Ovary Syndrome (PCOS) or thyroid problems can cause hormone levels to be unbalanced in women, which may lead to issues with fertility among other problems.

Low levels of testosterone or other hormone imbalances can affect sperm production.

Infertility can be related to problems with ovulation – the process where the ovaries release an egg each month as part of the female reproductive cycle. If there is no ovulation, pregnancy can’t occur during that cycle.

Some people may not ovulate at all, while others may ovulate irregularly. Conditions like PCOS (Polycystic Ovary Syndrome), thyroid issues or premature ovarian failure, among other conditions, can prevent regular ovulation.

Genetic conditions are due to changes affecting the genes or the amount of genetic material (like the number of chromosomes). Sometimes, genetic issues can affect fertility. Some people might be born with genetic conditions that affect their reproductive organs or how their bodies produce eggs or sperm.

For example, conditions like Klinefelter syndrome or Turner syndrome can lead to infertility. Klinefelter Syndrome (KS) is a condition that affects men. Chromosomes are packages of genes found in every cell in the body. There are two types of sex chromosomes that determine the genetic sex of a baby – these are named X or Y.

A male baby usually has one X and one Y chromosome (XY) and female babies have two chromosomes (XX). If you have Klinefelter syndrome, you’ll be born with an extra X chromosome (XXY).

KS is the most common type of chromosomal difference. It can affect how the body makes testosterone and this can lead to challenges with producing sperm.

Turner syndrome is a female-only genetic condition. Normally, girls have two X chromosomes, but girls with Turner syndrome have only one normal X chromosome and are missing part or all of the other X chromosome.

Most girls with Turner syndrome may have underdeveloped ovaries, which means they usually don't have periods and might not be able to have children.

What you eat and how active you are can impact your fertility. Being underweight or overweight can affect hormone levels, making it harder to conceive. Regular exercise is good, but too much intense exercise can also have a negative effect.

Smoking, alcohol and recreational drug use can all negatively affect fertility. For instance, smoking can damage eggs and sperm, making it more difficult to conceive.

High levels of stress can affect hormone levels and make it harder to get pregnant or maintain a healthy pregnancy.

Conditions like diabetes, autoimmune diseases and certain cancer treatments can affect fertility. Some illnesses might directly impact reproductive organs, while others might make it harder to get pregnant or cause complications during pregnancy.

Additionally, some medications needed to manage chronic conditions might have side effects that impact fertility. For example, some cancer treatments can affect both egg and sperm production.

If you think that any prescribed medication that you may be taking may be affecting your fertility, it is important to continue taking the medication as prescribed and speak to your prescriber about any concerns you may have.

Furthermore, using illegal drugs can also reduce sperm quality.

As people age, their fertility naturally declines. This is true for both those with ovaries and those with sperm. For women, the number and quality of eggs decrease with age, especially after the age of 35. Men also experience a decline in sperm quality as they get older.

Sexually transmitted infections (STIs) like chlamydia and gonorrhoea can cause damage to the reproductive organs if not treated, possibly leading to infertility.

If left untreated, inflammation caused by these infections can cause structural damage in the reproductive organs such as blocking fallopian tubes (structures that connect the ovaries to the womb) or damaging sperm ducts.

Certain infections that are not sexually transmitted can also affect fertility. For example, mumps (if caught after puberty) can cause inflammation of the testicles, potentially leading to infertility.

Sometimes, the shape or structure of reproductive organs can cause infertility. For example, blocked fallopian tubes, fibroids (non-cancerous growths in the womb), or issues with the shape of the womb.

Sperm are made and stored in the testicles, so any damage to the testicles can affect sperm quality. This damage could come from things like testicular cancer or surgery, infections, or injuries. There might be blockages in the tubes that carry sperm or issues like a varicocele (enlarged veins in the scrotum) can affect sperm quality.

Surgeries on reproductive organs, whether for treating health conditions or other reasons, can sometimes leave scar tissue. This scar tissue can block eggs from travelling through the fallopian tubes or affect sperm movement.

Sometimes, despite all tests and evaluations, the cause of infertility can’t be found. If this happens, your doctor can discuss the next steps with you.

For women, there are ovulation tests that can help you figure out when you’re most likely to get pregnant. These tests work by checking for a rise in luteinising hormone in your wee (this is a hormone that increases just before you ovulate). Knowing when you ovulate can help you understand your fertile days, however, these tests don’t tell you everything about your overall fertility. We’ve put together a guide on what you need to know about ovulation tests.

Another way to track your fertility is by monitoring your body temperature. We’ve covered this in the ‘When are you most fertile?’ section of the page.

For men, there are at-home sperm tests, like the one that can give you an idea of how many sperm there are in your semen. While these tests can be a starting point, they might not show other important factors like how well the sperm are moving or if they have the right shape.

IVF is a process where you take medicine to encourage your ovaries to produce more eggs than usual. These eggs are then collected and fertilised with sperm in a lab.

Usually, the eggs and sperm are mixed together to allow the sperm cells to fertilise the eggs, but if there are issues like a low sperm count or poor sperm quality, a single sperm can be directly injected into an egg. This is called intracytoplasmic sperm injection (ICSI), and it can improve the chances of conception since the sperm doesn’t need to penetrate the egg on its own.

After fertilisation, the eggs are placed in the womb with the hope that they will grow and develop into a pregnancy.

You can find more information about IVF and learn what to expect in our guide.

Intrauterine insemination (IUI) involves separating higher-quality sperm from sperm that isn’t moving well. The higher-quality sperm is then placed directly into the womb, where it can meet the egg.

While this might seem like a treatment for low sperm count or lower-quality sperm, some research shows it doesn’t necessarily increase the chances of pregnancy for these issues. Because of this, it’s not usually offered on the NHS for low sperm count or sperm quality alone.

You might be offered IUI on the NHS for free if:

• You’re unable to have vaginal sex due to a physical disability or a psychosexual issue
• You have a condition that requires help to conceive, such as if one partner has HIV and it’s not safe to have unprotected sex
• You’re in a same-sex relationship and haven’t become pregnant after up to six cycles of IUI using donor sperm from a licensed fertility clinic

The waiting list for IUI treatment can be long in some areas, and the criteria for eligibility can vary, so it’s a good idea to check with your GP or local Integrated Care Systems (ICG) to find out the rules where you live.

If there’s an issue with your eggs or sperm, you might be able to use a donor to help you conceive. Treatment with donor eggs usually involves IVF.

If someone registered to donate eggs or sperm after April 1, 2005, they must provide information about their identity. This is because any child born as a result of donated eggs or sperm has the legal right to learn the identity of the donor when they turn 18.

Semen quality means the health and characteristics of sperm cells in the semen, including their count, shape and ability to move. One of the most common reasons men have trouble with fertility is due to lower-quality sperm and semen. This can happen for a few different reasons. Some men might have a low number of sperm in the semen or none at all.

Others may have sperm that don't move well, or that are shaped differently than usual. Even if sperm cells look normal, they might have damaged genetic material, which can make it harder to conceive.

Increased temperature in the testicles can affect sperm quality. If the scrotum (the skin that holds the testicles) gets too warm, sperm quality might decrease. Things like cycling, taking hot baths, working in hot environments or using a laptop on your lap can all make the scrotum warmer.

Wearing loose underwear can help keep things cooler. Varicocele (enlarged veins in the scrotum) can also increase the temperature in the testicles and affect sperm production. Problems present at birth, like undescended testicles (when the testicles stay in the abdomen instead of going down to the scrotum before or around birth) may also affect sperm quality due to higher temperatures in the abdomen.

Some men experience problems with ejaculation that can make it difficult to release semen during sex. This could be due to various reasons, including medical conditions, previous surgeries or psychological factors. Ejaculation disorders can significantly affect fertility because they can prevent sperm from reaching the egg.

Ovulation is the release of egg cell(s) from the ovaries. Women are born with all the eggs they will ever have. After puberty, one egg is usually released during each menstrual cycle. Pregnancy can occur if sperm meets and fertilises this egg. Sperm can survive in the fallopian tubes for up to seven days after sex.

Sometimes, more than one egg is released during ovulation, and if both eggs are fertilised, it can result in twins or other multiple births. If ovulation doesn’t occur, pregnancy cannot happen. Some hormonal contraceptives, like the combined pill, patch or injection, work by preventing ovulation.

The time when you’re most likely to get pregnant is around ovulation. Although it’s hard to pinpoint the exact day ovulation happens, it usually occurs about 10 to 16 days before the start of the next period.

If you have a 28 day cycle, ovulation likely happens around day 14. However, this can vary if your cycle is shorter or longer. It’s also possible, though less likely, to get pregnant soon after your period ends, especially if you ovulate early or have a shorter cycle.

One way to track your ovulation is by monitoring your basal (resting) body temperature. There’s a small rise in your body’s basal temperature just after you release an egg (ovulation) and it can help you understand your cycle better.

To do this, you’ll need either a digital thermometer or one designed specifically for natural family planning (you can find these at pharmacies).

It’s important to know that ear or forehead thermometers won’t give you accurate readings for this purpose. To check your basal temperature:

• Take it first thing in the morning before getting out of bed
• Do it before you eat, drink or smoke (if you smoke)
• Try to take it at the same time every morning

You’ll know you’ve ovulated when your basal temperature is higher for 3 days in a row than it was during the previous 6 days. The increase is small, usually around 0.2°C and it likely means you’re no longer in your fertile window.

As this increase in basal body temperature happens just after the ovulation, recording it daily for a few cycles can give you a better understanding of when you are likely to be most fertile.

We’ve put together our guide of advice for if you’re trying to conceive and vitamins that could help support your journey.

Women are born with a certain number of eggs in their ovaries, and this number decreases as they grow older. At birth, a baby has about 2 million eggs. By the time they become a teenager, this drops to around 400,000. By age 37, about 25,000 eggs remain. Each month, 1 egg matures and is released during ovulation, while the others are reabsorbed by the body.

As women age, both the number and quality of their eggs can decrease, which can affect their ability to get pregnant.

For men, sperm is produced daily rather than being present from birth. However, around age 40 to 45, the quality and number of sperm can start to decline, which might impact fertility.

If you’re concerned about how age affects fertility, there are tests available at pharmacies, online and at fertility clinics. It's also helpful to talk to a doctor if you have any questions or worries about fertility.

You can check your fertility in a few different ways, and it’s a good idea to start by talking to your doctor if you have concerns.

For women, doctors might suggest blood tests to check hormone levels, an ultrasound to look at the ovaries and uterus, or tracking your ovulation at home. There are also home ovulation tests that can help you know when you’re most likely to get pregnant.

For men, a semen analysis is often done to check the number and quality of sperm. Some home tests can give you an idea about sperm count, but seeing a doctor will give you a more complete picture.

If you’re worried about your fertility, your doctor can guide you through the best steps and answer any questions you have.

There are several lifestyle changes you can make to help improve your fertility:

• Eat a balanced diet
• Exercise regularly – regular physical activity helps maintain a healthy weight, which is important for fertility. Just be careful not to overdo it, as too much intense exercise can sometimes have the opposite effect
• Quit smoking
• Limit alcohol and avoid recreational drugs
• Manage everyday stress
• Get enough sleep

Making these changes can help you feel healthier and improve your chances of getting pregnant. If you’re unsure where to start, your doctor can give you personalised advice.

If you've been trying to get pregnant for a year without success, or for 6 months if you're over 36, it's a good idea to talk to your GP or a specialist. You should also speak to a doctor if you’re worried about your fertility, for example, if you’ve had cancer treatment or you might have had a sexually transmitted infection (STI).

They can help figure out if there's anything affecting your fertility and guide you on what steps to take next.

You are most likely to get pregnant around the time of ovulation, which usually happens about 10 to 16 days before your next period. If your cycle is regular, you can track this time to know when you're most fertile.

Another way to help track ovulation is by checking your basal (resting) body temperature. After ovulation, your basal body temperature rises slightly, about 0.2°C. By taking your temperature each morning before getting out of bed, you can spot the small increase and better understand your fertile window.

Infertility can be caused by various factors, such as problems with ovulation (the ovaries releasing egg(s), blocked fallopian tubes (tubes connecting the ovaries with the womb), low sperm count or health conditions like polycystic ovary syndrome (PCOS). Sometimes, the cause is unknown. If you're concerned about infertility, a doctor can help identify the reason and suggest possible treatments.

We’ve explored this more in the ‘Causes of infertility’ section of the page.