The female body is quite fascinating, and we love finding out about unearthed — or somewhat glossed over — facts about it.
For instance, one “Did You Know” quote that was recently doing the rounds on social media reads: Did you know, your grandmother carried parts of you inside her womb? A female baby is born with all the eggs cells (called ova or oocytes) it will ever have in its lifetime, so that means that while you were in your mother’s belly, so were all your eggs — and potential children! It’s pretty mind-blowing to think about.
We break it down some more and share a few extra interesting nuggets — all about eggs!
A bit about eggs
Ova are formed and dwell inside the ovaries; each one lying dormant inside its own little follicle. Ovaries are small oval-shaped glands, roughly the size of a large grape, located on either side of the uterus. (The male counterparts of the ovaries are the testes — also known as gonads. Yup. Gonads.)
Linking the ovaries and the uterus are the fallopian tubes, which are connected to the ovaries via tissue called fimbria. As well as producing eggs, ovaries also produce two groups of sex hormones: progesterone and oestrogen. These hormones promote healthy female development during puberty and fertility.
Even though most cells in the human body can’t be seen without the aid of a microscope, egg cells are one of the largest cells in the human body, roughly the width of a strand of hair, and almost 15 times larger than a red blood cell (egg cells measure over 100 microns and red blood cells approximately seven microns each).
Once menstruation starts in puberty, usually one cell is released every cycle during the ovulation process. (Some women release two eggs per cycle and this could lead to conception of fraternal (non-identical) twins; identical twins are formed from one fertilized cell that splits after conception.)
How many eggs do women have at each stage of life?
Females produce approximately six to seven million eggs as foetuses, and these are non-renewable, which means that no new eggs are produced at any point thereafter.
By the time we are born we have around one million eggs. 11,000 of these will have died by the time we reach puberty, at which time we will have around 300,000 left. Of those, only 300 to 400 will be ovulated as from puberty onwards approximately 1,000 eggs will die each month due to “natural cell death” — a process which only accelerates as we get older and can’t be stopped.
To break it down further, according to the 2010 report titled “Human Ovarian Reserve from Conception to the Menopause,” women at each age have approximately:
Foetus: 6-7 million eggs
Birth: 1-2 million eggs
Age 13: 3-400,000 eggs
Age 20: 250,000 eggs
Age 25: 170,000 eggs
Age 30: 120,000 eggs
Age 35: 80,000 eggs
Age 40: 50,000 eggs
Menopause: less than 1000 eggs
The report goes on to estimate that for 95% of women by the age of 30, “only 12% of their maximum pre-birth non-growing follicle (NGF) population is present and by the age of 40 years only 3% remains.”
As we get older, the quality of the eggs deteriorates, and — contrary to popular belief — this happens regardless of external factors, such as birth control or hormone treatments, etc. Our DNA repair mechanisms start to get less effective as we age causing genomic damage. Menopause starts when the supply of eggs runs out as the ovaries then cease to make oestrogen. Most studies indicate that menopause usually happens between the ages of 40-50, but in rarer cases this could be earlier or later.
The journey of the egg
All follicles and egg cells are immature (or primordial), until the beginning of the ovulation cycle (usually the seventh day after the start of your period) where, due to hormone stimulation, hundreds of them start to develop and mature in an attempt to become the egg that is selected for release and potential fertilization — the Dominant Follicle.
Around days 10-14 after your period, the egg in the dominant follicle which is significantly larger and more mature than the others (and can grow up to 1.2 inches!) ruptures and bursts out of the follicle and is released into the fallopian tube. The other eggs that tried but didn’t quite make it get reabsorbed in a process called “follicular atresia”. Basically they die.
In a five day journey, the egg starts to make its way down the fallopian tube to the uterus in the hopes of meeting Prince Sperm Charming. If this fateful meeting doesn’t happen by the time the egg reaches the uterus and there is no fertilisation, menstruation begins. The egg’s condition starts to deteriorate pretty quickly after it’s released into the fallopian tube so the best time for a perfectly timed meet-cute with the sperm would be the day of, or day before, release.
How many eggs do I have left?
You won’t be able to check how many eggs you have left by taking an online quiz. The above calculations are an average and every woman is different. The best way to check the status of your eggs is to arrange an antral follicle count via ultrasound for your doctor to count the visible follicles. Your doctor won’t be able to give you a precise count, but they will be able to tell you if you have a good, medium, or low egg count.
Another way to see how many eggs you have left is via an anti-Müllerian hormone (AMH) test. Blood is drawn and the level of AMH — a protein hormone produced inside the follicles — is determined, thus helping doctors collect the total number of follicles inside the ovaries, and therefore a good estimate of the total egg count.
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