Age And Fertility: What You Need To Know

Most people are aware that age impacts fertility; however, many don’t understand the extent of this or how it occurs. Is fertility a linear decline as you age, or could other factors contribute to it? Is this a manageable issue, with effective ways to overcome age-associated infertility? This article will clarify the connection between age and fertility over time. 

Age can determine the fertility of those assigned female at birth (AFAB), due to egg quantity and quality declining with advancing age. Unlike people assigned male at birth (AMAB) who continuously produce new sperm cells over their lifetime, those AFAB are born with a finite number of eggs that cannot be regenerated or replaced. However, both sexes experience a decline in fertility as they grow older.

Every person is unique and it’s empowering to know how age and other factors can influence your reproductive health. Whether you are navigating your career, family planning, or simply want to know more, this article will provide you with the guidance you need. 

Background: why age impacts fertility

Infertility is a pressing issue and is recognised as a global health problem by the World Health Organisation (WHO).¹ 

With social trends shifting significantly over the last few decades, many people are deciding to have children later in life. This trend is influenced by many societal and personal reasons, including financial influences, pursuit of further education, finding suitable housing, and meeting a partner later in life.² 

For many people, career demands, increased job opportunities, and a fast-paced work culture promote professional growth and personal development as a priority over family planning.¹ This has led to a significant increase in people attending fertility clinics in search of help, as the natural decline in fertility becomes more of a pressing issue.¹

When does fertility start to decline? 

The number of eggs in people assigned female at birth (AFAB) is shown to decrease over time as you age.² 

Fertility tends to decrease noticeably around the age of 32, but a staggering decrease especially around 37 years of age.^1,2 The probability of getting pregnant naturally at 40 years old is around 44%, compared to those under 30 having approximately 85% chance of conceiving.² 

Fertility tends to decrease after the age of 30 for those assigned female at birth.²

Egg quantity and quality

Determining fertility in those assigned female at birth (AFAB) involves the quality of your eggs and the number of fertile eggs released, both of which reduce over time as you age.^1,2 

A common misconception is that people who are assigned female at birth produce new eggs each month. However, they are born with a fixed number of immature eggs, typically between one and two million. This finite number decreases as you grow older.³ 

During each menstrual cycle, the eggs mature and are released during ovulation, while others often get reabsorbed by the body. This cycle repeats from puberty through to menopause.³ 

As the number of eggs declines over time, so does the probability of having a natural conception. The rate of egg loss increases as you age.^2,3 

Egg quantity can involve individual factors too, such as lifestyle and genetic factors, however, these are not primary determinants.³

The decline in egg quality as you age is just as important. There are increased chances of carrying abnormal chromosomes in the remaining ageing eggs, leading to potential future complications. 

While this circumstance can be rarer, this risk increases with age, leading to life-threatening syndromes such as Down syndrome, Patau syndrome, Edwards syndrome, and other potential birth defects.⁴ 

Prenatal screening and genetic tests are crucial to assess potential risks during pregnancy.

It is not just women: men and fertility

People assigned male at birth (AMAB) also experience a decrease in their fertility as they age, particularly from around 40-45 years.⁵ 

People AMAB are not born with a set amount of gametes, and instead, continue to produce new sperm daily throughout their lives. 

The production and quality of sperm decreases with age, particularly around the 40-45 year age mark.⁵ Sperm DNA damage has been correlated with genetic disorders in offspring too, including a higher risk of Down syndrome.^1,5 

Hence, people of all genders can struggle with fertility challenges as they age, although those assigned male at birth tend to have longer fertility periods compared to those assigned female at birth. 

Other factors that contribute to infertility

While age is a huge factor, those in their ‘prime age’ for fertilisation, can also experience fertility issues. Some of these reasons are known, while others can be less obvious.

Lifestyle factors such as smoking, excessive alcohol, drug usage, having a high BMI, and excess caffeine intake can greatly impact your fertility rate.⁶ 

Having or having experienced a sexually transmitted infection (STI) can also affect your reproductive organs. Medical conditions such as Ppolycystic ovary syndrome (PCOS), can also interfere with conception.

There is an increased likelihood of developing endometriosis, uterine fibroids, and other health conditions as you age, which can affect fertility. 

In those assigned males at birth, there are a variety of conditions that can reduce fertility. For example, factors such as having erectile dysfunction, having lower levels of sex hormones, or having less interest in sex can contribute to lower chances of success in conceiving.⁷ 

Can age affect my pregnancy?

In addition to impacting fertility, age can also increase risks during pregnancy stages, such as miscarriage. 

Statistics show more than half of pregnancies can lead to miscarriages after the age of 45.⁸ 

Once surpassing the age of 35, the chances of ectopic pregnancies and pre-eclampsia also increase.⁸ They tend to experience increased blood pressure, commonly causing pre-eclampsia and other conditions that can affect both maternal and foetal health. 

Hence, it is recommended that you discuss if you are planning to have children at a later age with your GP.

Are there ways to overcome age-related infertility?

Thanks to advances in reproductive medicine, there are several great alternatives. 

Having fertility tests performed in clinics or purchased in pharmacies is a great first step.

Egg freezing is another option, where freezing your eggs before age 35 can lead to higher success rates. 

Discussing your concerns with your GP can help you navigate other methods that may be of interest, including assisted conception.

Fertility treatments and In Vitro Fertilisation (IVF) options are great options to consider. For those in the UK, some IVF programmes may be fully covered by the NHS if you meet the NICE criteria. However, success rates of IVF can also decline with age.

Intake of prenatal vitamins and folic acid early in advance can assist with preventing neural tube defects and other risks.

Summary 

Age is a common determinant of infertility; however, it is not impossible to have children if you are over a certain age. 

Infertility typically increases after 35 years old for people assigned female at birth and after 40-45 years old for those assigned male at birth. 

Both the quality and quantity of eggs and sperm decrease over time. Despite this, family planning, lifestyle modifications, and alternative methods of conceiving could be better choices for both the well-being of yourself and your family.