Fertility Timeline: When Is a Woman Most Fertile?

With the UK average age for having a baby currently 30.7 , there is a steady trend towards having children later in life. But this can lead to potential issues in conceiving, the older a woman gets. So, is there really an optimum time to start a family? 

We countdown the fertility timeline to ask – when is a woman most fertile?

The starting point

Women are actually born with all the eggs they will ever have, which is an estimated one to two million. However, by the time a woman reaches puberty and starts her period, this number will have been reduced to around 400,000, which will then need to last for the duration of their reproductive life. 

With each period, several hundred eggs will be lost, and it is only the healthiest egg follicles that go on to be mature eggs. And, as the body ages, the number of egg follicles inevitably reduce. 

With this finite supply of eggs, it is important for women to be aware of their own fertility timeline, so they know when the best time is to try for a baby. 


From a physical and biological point of view, your late teens and 20s are the best age to have a baby as your body will be at the prime of its fertility health. During this period, your body is still accessing the strongest ovarian follicles from its supply, and these will mature into eggs that are more likely to be a higher quality. However, many young women are not yet ready to start a family, with their focus on careers and a single life, or finding the right life partner. 

The risks are also generally at their lowest when it comes to potential birth defects, chromosomal problems, and pregnancy-related illnesses. The chances of fertility issues are also reduced, with the odds of a 25-year-old conceiving after three months around 20%, compared to 12% for a 35-year-old. 


By your early 30s, your fertility levels and therefore your chances of conceiving should still be relatively high, and your egg supply will still be high quality.  For many women, their careers have also been established by their third decade, they are more likely to be in a stable financial position to start a family.

However, your 30s are also when your fertility levels start to naturally decline, beginning at around the age of 32 and by the age of 35 your chances of conceiving have dropped to around 12% (after three months of trying). 

Statistics show more women are now getting pregnant in their early 30s than they are in their 20s. However, around one in three couples in their 30s will also experience some form of infertility. But that doesn’t mean they cannot have children, as 30-somethings seeking advice and support from their local health care provider or private fertility clinic still have a 35% chance of conceiving through IVF. 


Fertility levels decline at a greater speed after the age of 35 and, by the age of 37, it is estimated that women have around 25,000 eggs left. But it is still possible to naturally conceive a child during this time, with estimates indicating that around 60% of 35-40-year-olds falling pregnant within a year of trying. 

However, the potential health problems associated with pregnancy do increase, including chromosomal issues, and raised risks of miscarriage. 


Your early 40s see the greatest reduction in fertility levels, effectively halving the chance of a natural pregnancy, compared to a woman in her early 20s. By your mid-40s, your body is preparing for or already has entered the menopause phase and is most likely reaching the end of its egg follicle supply. This raises the risk of pregnancy abnormalities and miscarriage even higher as well as the potential health risks to the mother-to-be. 

But while can be tougher for women or couples who wait to get pregnant in their 40s, it is still possible to conceive, with IVF and associated treatments that can help to extend that all-important fertility window. 

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One thought on “Fertility Timeline: When Is a Woman Most Fertile?

  1. Polly says:

    In this case, these are general statistics, but there may be different cases, there may be health problems, in connection with which you will not be able to get pregnant naturally. Here, IVF comes to the rescue, air transfers of frozen materials services like this one https://arkcryo.com/shipping-services/ are really at a high level. This gives you a chance to become a parent again.

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