5 Facts About the Female Egg Cell

Get ready to learn some surprising facts about the female egg cell! In this post, we’ll dive deep inside the workings of the menstrual cycle and explore the small and fragile cell that’s crucially important when it comes to fertility. Read on to find out why human eggs are so special and how the life of the egg cell is closely tied to planning or preventing pregnancy...

Red female egg cell on a pink background with the text 'the egg cell survives up to 24h'

This article is also available in Spanish.

1. The female egg cell is bigger than you think

Most cells aren’t visible to the naked eye: you need a microscope to see them. The human egg cell is an exception, it’s actually the biggest cell in the body and can be seen without a microscope. That’s pretty impressive.

Compared to the other human cells, egg cells are huge. They are 100 microns in diameter (that’s a millionth of a metre) and are about as wide of a strand of hair. That may sound small, but no other cell comes close to being that large.

2. You are born with all your egg cells

Did you know that every woman is born with all her eggs already inside her ovaries? You can have as many as seven million eggs in your ovaries when you are born and these will be released every menstrual cycle throughout your fertile lifetime. 

Because you’re born with all your eggs, this actually means that your eggs were once inside your mother when you were a fetus in her womb. That means your mother carried the egg cells which may one day be fertilized and grow into her own grandchild! 

3. The quality of human eggs gets worse over time

As we get older, so do our cells and the female egg cell is no exception. Although women are born with millions of eggs, the quality of these goes down over time. Many die off before we even hit puberty, meaning we’re left with around 700,000 egg cells by the time menstruation begins.

Each month a woman continues to lose egg cells, so at the point of menopause, a woman will likely have fewer than 1000 egg cells left. It’s a common misconception that hormonal birth control or pregnancy can pause the natural deterioration of female egg cells. These continue to deteriorate regardless. 

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4. An egg cell is released every cycle

Most women release an egg cell every cycle, this is called ovulation. Some women can release two egg cells per cycle, this can result in the conception of paternal or fraternal twins. Identical twins are made when the fertilized egg cell divides in two. Identical twins grow in the same amniotic sack and, unlike fraternal twins, are genetically the same.

Hormonal birth control works by suppressing ovulation. This is how pregnancy is prevented, by removing the egg cell from the equation altogether. When ovulation doesn’t happen in a regular menstrual cycle, this is called an anovulatory cycle. Anovulatory cycles are common and most women are likely to experience them at some point in their lives. You may not realize you haven’t ovulated if you aren’t tracking your menstrual cycle. 

5. The female egg cell has a short life after ovulation

Once ovulation has happened, the female egg cell that’s released starts to deteriorate very quickly and the fertile window starts to close. After 12-24 hours the egg cell will die and it won’t be possible to become pregnant again until the next cycle. 

For this reason, the best time to conceive is actually the day before ovulation. Compared to egg cells, once released, sperm are more resilient and can survive in the female reproductive tract for up to five days! Sperm survival is dependent on the right conditions, such as the consistency of cervical mucus. Identifying ovulation is a key step in planning a pregnancy

Birth control and the menstrual cycle

Just as knowing when you’re fertile can help plan a pregnancy, this science can also be used to prevent pregnancy. Once you have identified the fertile window, there are only six days in the menstrual cycle when it’s possible to become pregnant. Abstaining from sex, or using a condom on days when there is a risk of pregnancy is a non-hormonal method of birth control.

The tricky part comes in when you consider the fertile window opens before ovulation even happens, so by the time you’ve ovulated, it’s too late to prevent pregnancy. This is where Natural Cycles comes in. By taking your temperature regularly and inputting it into the app, it’s possible to learn your unique cycle and find ovulation through a rise in body temperature. 

Unlike traditional fertility awareness-based methods, Natural Cycles is powered by an algorithm which can learn the pattern of your unique cycle and predict ovulation. This means that the method is tailored to you, and unlike the calendar method, it does not predict your fertility based on the average menstrual cycle.

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Written By

Jennifer Gray

A writer with a passion for women’s health, Jennifer Gray has years of experience writing about various reproductive health topics including birth control, planning pregnancy, women’s anatomy, and so much more.

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Scientifically Reviewed

Jack Pearson

With 10 years of experience working in the field of fertility, Jack Pearson is Natural Cycles’ in-house expert. As Medical Affairs Manager, he dedicates his time to conducting groundbreaking research and educating healthcare professionals.

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