If you’re wondering how age affects fertility, you’re not alone. It’s one of the most common questions people ask when they start thinking about trying for a baby, delaying pregnancy, or looking into fertility treatment.
The simple answer is that age does affect fertility. But it isn’t the only factor, and it doesn’t tell you everything about your chances of getting pregnant. Understanding how age can affect egg quantity, egg quality, sperm quality, and fertility treatment success can help you make more informed decisions about what to do next.
According to Dr Joana Guimarães, Medical Director at Procriar, fertility is usually highest in the twenties and early thirties.
For many women, it starts to decline gradually in the early thirties and more noticeably from the mid thirties onwards.
Here’s why:
Ovarian reserve decreases over time
Women are born with all the eggs they will ever have, which means the ovaries do not make new eggs later in life. Over time, the number of eggs left in the ovaries naturally decreases.
This happens because, in each menstrual cycle, a group of eggs begins to mature, but usually only one egg is released during ovulation. The rest are lost as part of the body’s natural process. Over the years, this causes egg numbers to fall. The number of eggs you have left is known as your ovarian reserve.
Egg quality also declines with age
Egg quality is a key part of fertility. It refers to how likely an egg is to have the correct number of chromosomes and develop normally after fertilisation. As eggs get older, they are more likely to have chromosomal abnormalities.
One of the reasons why egg quality declines with age is that older eggs may not have the same energy supply as younger ones. Eggs rely on structures called mitochondria to provide the energy needed for important processes, including chromosome division after fertilisation. As eggs get older, this process can become less efficient, which may increase the chance of errors.
As you get older, both egg quantity and egg quality naturally decline. This can affect your chances of getting pregnant, your chances of creating healthy embryos, and your risk of miscarriage.
Dr Guimarães says:
This does not mean pregnancy is impossible after 35 or 40. Many women do conceive naturally later in life, although it can take longer and may be less predictable.
Caption:
This image shows a mitochondrion, the part of the cell that produces energy. In eggs, mitochondria help power key processes needed for normal development, which is why they are closely linked to egg quality.
Male fertility and age
Male fertility can change with age too, but not in the same way as female fertility.
Unlike women, men continue to produce sperm throughout life. However, sperm quality can still decline over time. This may affect sperm movement, shape, and DNA quality. In some cases, it can affect fertilisation, embryo development, or miscarriage risk.
For men, these changes usually happen more gradually. Female fertility is more closely linked to age because women are born with all the eggs they will ever have, and both egg quantity and egg quality decline over time. Men do not experience that same pattern, but age can still play a part in the overall fertility picture.
How does age affect IVF success rates?
Age is one of the most important factors in IVF success rates, especially when treatment uses your own eggs.
This is because egg quality has a strong effect on fertilisation, embryo development, implantation, and miscarriage risk. As age increases, the chance of having chromosomally normal embryos usually falls.
That does not mean IVF cannot work in your late thirties or forties. Many patients do have successful IVF treatment at these ages. But it may take longer, require more than one cycle, or involve a different treatment plan.
If you are worried about age and IVF success rates, the most useful thing you can do is speak to a fertility specialist about your personal results rather than relying only on averages.
Can you get pregnant naturally as you get older?
Yes, natural pregnancy is still possible as you get older. Many women get pregnant naturally in their late thirties and early forties.
But age does reduce fertility over time, and it can take longer to conceive. Miscarriage risk also tends to rise with age because older eggs are more likely to have chromosomal abnormalities.
If you have been trying for a baby without success, it may help to seek advice sooner rather than later, especially if you are over 35.
What age should you see a fertility specialist?
If you are under 35 and have been trying to get pregnant for 12 months without success, it is usually a good idea to book a fertility assessment.
If you are over 35, we recommend seeking advice after 6 months of trying.
You may also want to speak to a fertility specialist earlier if you have irregular periods, known fertility concerns, a history of miscarriage, endometriosis, PCOS, low ovarian reserve, or if you want to understand your fertility before trying.
How fertility testing can help
Fertility tests can give you more information about how age may be affecting your fertility.
For women, fertility testing may include:
An AMH blood test, which measures the level of anti Müllerian hormone in your blood. This can help show your ovarian reserve, meaning your egg quantity.
An antral follicle count scan, which is an ultrasound that counts the small follicles in your ovaries that contain immature eggs. This can give doctors more information about how many eggs you may have left and how your ovaries may respond to fertility treatment.
Hormonal tests, such as FSH and estradiol, that can provide an indication of your ovaries’ functional status.
Together, these fertility tests can give doctors a clearer picture of your ovarian reserve and overall fertility. They can’t show egg quality directly or predict whether you will definitely get pregnant, but they can provide a useful starting point for understanding your fertility.
For men, fertility testing usually includes a semen analysis. This looks, among other parameters, at:
Sperm count, which shows how many sperm are present in the sample.
Sperm movement, also called motility, which shows how well the sperm swim.
Sperm shape, also called morphology, which shows whether the sperm have a normal structure, which can affect their ability to reach and fertilise an egg.
The main benefit is that your eggs are frozen at the age they are collected. This means that if you freeze eggs at a younger age, you may preserve the benefit of younger egg quality for later use.
Egg freezing is not a guarantee, and success depends on factors such as your age at the time of freezing and how many mature eggs are collected. But for some people, it can be an important way to protect future fertility options.
Thinking about egg freezing?
Get clear, expert advice on your fertility, your timing, and whether egg freezing may be the right option for you.
This is because the age of the egg has a major effect on treatment success. When the eggs come from a younger woman, egg quality is usually higher, which can improve the chance of creating healthy embryos and achieving pregnancy.
Even in donor egg IVF, the person carrying the pregnancy still plays an important role. The embryo’s DNA comes from the egg donor and sperm source, but the uterine environment helps support implantation, placental development, and the growth of the baby. Research also suggests it may influence how some genes are expressed during pregnancy.
Donor egg treatment is not the right path for everyone, but it is an important option to know about when age related fertility decline is affecting treatment outcomes.
careful screening for genetic and infectious diseases, as well as psychological evaluation
detailed donor profiles, with information on physical characteristics, personality, emotional intelligence, education, hobbies, and dreams
support from our Donation Team, who can help you explore your options, understand what matters most to you, and find a suitable match
exclusive donor reservation, so when we send you a proposed donor profile, that donor is held for you for 3 working days while you decide
genetic compatibility testing, to help identify most shared gene mutations between the patient and donor and reduce the risk of certain genetic disorders, screening up to more than 2000 recessive diseases
Our donor programme is open ID. This means donor conceived children can access information about the donor’s civil identity once they turn 18, as per the Portuguese Law. Donors cannot contact the child themselves and have no legal rights or claims over them.
It is important to say this clearly: this is not about blame.
People delay having children for many different reasons, including relationships, work, finances, health, or simply not being ready yet. These are real life circumstances, not mistakes.
Good fertility care should give you clear information, help you understand your options, and support you without judgement.
What you can do now
If you are concerned about age and fertility, there are practical steps you can take.
Get the right information
A fertility assessment can help you understand your ovarian reserve, your likely treatment options, and whether there are any signs that age is affecting your fertility.
Do not ignore concerns
If something does not feel right, or if you have been trying for a while without success, getting checked sooner can give you more clarity and more options.
Think about your timeline
If you know you want children in the future, it may help to have an honest conversation about timing, fertility testing, or egg freezing.
Support your general health
Lifestyle factors can’t stop age related fertility decline, but they can still support reproductive health. Not smoking, limiting alcohol, eating well, sleeping well, and maintaining a healthy weight can all help.
A final word on age and fertility
Age matters when it comes to fertility, but it is only one part of the picture. It can affect egg quantity, egg quality, miscarriage risk, and IVF success rates, but it does not define your future on its own.
The most useful next step is to get clear information about your own fertility and talk through your options with a specialist.
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