The fascinating story of your reproductive biology.
If you’re thinking about starting a family, then you may have spent a little more time than usual thinking about your biology. Is your body healthy and ready to have a child? Is your reproductive system working like it should? If you’re a woman you may even be focused on your eggs and the role they will play in creating a new life. How many do you have and what sort of shape are they in? These are all important questions that you may need to answer before you have a child. In fact, learning about your natural reproductive biology can help gain a better understanding of how your body works and focus your efforts to conceive.
We have explored the story of the human egg, from how many women have to how modern fertility treatment can help you measure and store yours. Learn more, below.
How many eggs will I produce in my lifetime?
The number of eggs you have in your body is determined before birth. Unlike most parts of your body like skin and bone, they do not naturally renew. Even as a foetus you have egg follicles present, although that number steadily decreases as you mature into a baby. A 20-week-old foetus has a staggering 7 million egg while a newborn female baby has about 2 million. During the years before puberty, this number drops still further to around 300,000 to 500,000. This reduction in egg numbers is completely natural and the number of eggs you have at puberty is normally more than enough to see you through the fertile period of your life.
Your body will never create new eggs and this supply will gradually dwindle until you reach the menopause, when your egg stores are spent and you are no longer able to have a baby naturally. The number of eggs your body has drops off most steeply after 35 when many women experience a natural decline in fertility.
How many eggs do I release every month?
Although only one egg is released by the ovaries each month, that doesn’t mean that more eggs aren’t lost. Egg follicles exist in a ‘sleeping’ state before they mature, and one is eventually released. During your cycle, a large number of follicles begin to develop into mature eggs but only one is deemed viable and sent on its way. The other ‘understudy’ follicles that have begun to mature are reabsorbed by the body and effectively lost. A woman may lose 1000 or more eggs each month due to eggs that didn’t quite make the grade and natural cell death. As she ages, this number increases, signalling a decline in fertility as she approaches menopause. Over the course of her life, a woman will release around 500 viable eggs.
Can fertility drugs help me produce more eggs?
No drug, supplement or treatment can increase your egg stores. You are born with a finite number of eggs and it is impossible to increase this number. However, it is possible for fertility drugs to increase the number of mature eggs produced in one cycle, allowing them to be harvested and frozen, perhaps for use in fertility treatments like IVF. This, in effect, increases the quantity of viable eggs your body produces, if not the overall number. This process of making the most of the eggs you have left can be very helpful for women with fertility challenges or older women who want to extend their remaining fertility.
How are eggs linked to my biological clock?
A woman’s egg production is directly linked to her fertility. And when her egg supplies have run down and finally out, this spells the end of the naturally fertile period of her life. When people talk about your ‘biological clock’ they are really talking about how many eggs your body has available. Frustratingly, fertility does not run down smoothly in a gentle curve from puberty to menopause. Egg production gently tapers down between puberty and around 35 but then drops off steeply into the 40s and early 50s.
Can I find out how many eggs I have left?
Normally, you don’t need to know how many eggs you have left. Your body will regulate the egg release process completely naturally. But if you do come across fertility problems this may be an option your doctor suggests. It will help you understand how many eggs you have left and pinpoint any problems with egg production or release. There are two main ways to get a handle on your egg count through an AMH (anti-Müllerian hormone) test or an Antral Follicle Count. Find out more about both, below:
AMH (anti-Müllerian hormone)
AMH is a special protein released by your egg follicles. By measuring the level of AMH in your blood, a fertility doctor can provide an estimate of the number of eggs in your ovaries. This is a useful test as it can be performed at any point in your menstrual cycle.
Antral Follicle Count
This test is an ultrasound scan that looks closely at the number of egg follicles in a woman’s ovaries. This test can provide meaningful data on both the total number of eggs remaining and the number that might be successfully harvested through fertility treatments. This test should be performed at the beginning of the menstrual cycle.
Are all of my eggs the same quality?
Fertility is not only linked to the number of eggs you produce but also to egg quality. Our eggs are with us from the very beginning and this means over time they can be damaged or degraded. Damage to an egg means damage to the DNA it contains, and this can impact on both fertility and the chance of a chromosomal abnormality in a developing foetus.
Egg quality, like egg production, declines steeply as we get older. A woman in her mid-twenties will produce embryos that are genetically normal 75% of the time, for a woman in her early forties this drops to around 20%. All this means, it gets tougher to get pregnant as women get older and fertility declines. Some women choose to freeze their eggs in their 30s or choose a younger donor egg to improve the chances of conceiving as they get older. This is an important consideration for women and couples contemplating IVF.
Can my lifestyle affect my eggs?
Even the healthiest lifestyle can’t impact the number of eggs you produce or the problem of decreasing egg quality as you age, but it can give your body the best possible chance to look after the eggs it has. Eating healthily, avoiding alcohol, and avoiding smoking can help to protect your eggs from further damage and encourage them to develop healthily.
A healthy lifestyle can also help to keep your hormone levels where they should be and promote normal follicle development. Stress can have a significant effect on fertility as high levels of stress hormone can stop ovulation. Sending a message to the brain that this is not a safe time to have a baby. So, as well as living well, mindfulness, meditation, and other relaxation techniques can help to support fertility.