The world of fertility and reproductive health can feel daunting and confusing at times, and there are some things — like how many eggs a woman (or anyone who menstruates) has — that may still remain a mystery to you. But if you’re trying to get pregnant or starting to pay more attention to your cycle for any other reason, you’ll probably have a newfound curiosity about what really goes on in there.
Understanding how many eggs you have, the process of ovulation (how many eggs you release each month), and what lifestyle factors impact your egg count will give you a better idea of how your body works and can empower you to make more informed decisions when it comes to your reproductive health.
Read on to understand more about female egg count and what it means for fertility. A Flo medical expert explains everything you need to know about eggs — from how many eggs you have in your 20s, 30s, and 40s to how ovulation occurs.
One of the weirdest and most wonderful facts surrounding female fertility is that the amount of eggs we have is determined while we’re still in the womb. Unlike men, who continue to produce sperm throughout their lives, a woman is actually born with all the eggs she’ll ever have.
“Women are born with approximately 2 to 3 million eggs,” says Dr. Lucky Sekhon, a reproductive endocrinologist and fertility specialist. “When a woman reaches puberty, her ovaries become capable of responding to signals from the brain, meaning ovulation can occur [and] pregnancy [becomes] possible.”
“During a woman’s cycle, thousands of eggs from both of the ovaries are prepared for ovulation,” explains Dr. Sekhon. But usually, only one makes the cut.
“Typically, you only release one egg each month, chosen at random,” she explains. “Whether or not ovulation occurs, the other eggs that have been prepared are discarded at the end of the cycle.”
Discarded eggs are either reabsorbed by the body or broken down and passed via your period. “The ovulated egg has 12 to 24 hours to be fertilized, and if not, it also disintegrates.”
We’re all too familiar with a woman’s “biological clock,” and that’s because age can very much impact your chances of getting pregnant. However, it’s not the only factor at play. Doctors work off a combination of other relevant information, including hormone levels, lifestyle factors, and genetics (more on this later) when figuring out how likely it is you’ll conceive.
“We know that after the ages of 35 to 37, we tend to lose eggs at a faster rate,” says Dr. Sekhon. “How many eggs we lose each month varies according to each person, but the process speeds up as we get older. For a woman aged 30, the chances of conception are around 20% each month; whereas for a woman who’s 40, it would be 5%.”
As you approach menopause (which, for most women, happens in their early 50s), your egg supply dwindles. At the age of 37, the average woman has around 25,000 eggs left, and by the time she reaches 51, this will have fallen to 1,000. “Just before menopause, your egg supply reaches below 1,000, and ovulations space out before they stop altogether, eventually,” says Dr. Sekhon.
It’s not just the quantity of eggs that depletes as you get older, however. It can be the quality, too. “Over the age of 35, we also see a significant rise in the rate of genetic errors in embryos,” Dr. Sekhon explains. As you age, she says, you’re also at an increased risk of an egg having chromosomal abnormalities (where the egg is missing or has extra DNA/chromosomes).
A healthy fertilized egg typically has 46 chromosomes (23 pairs). However, if they have too many or too few, it can cause problems with implantation (the process in which the fertilized egg attaches to the uterine wall) in pregnancy, and/or birth defects later down the line. “Embryos with these genetic errors will either not implant in the uterus, will implant but end in miscarriage, or they can result in the birth of a child with medical issues such as Down’s syndrome,” says Dr. Sekhon.
For women in their 20s and up to the age of 37, the average rate of genetic errors in embryos is somewhere between 2% to 6%. At age 42, this rate rises to roughly 33%, and by age 44, it becomes 53%.
But if you’re hoping to become pregnant later in life, don’t let these statistics scare you. Genetic disorders certainly don’t occur for everyone, and tests can be done throughout the pregnancy (usually in the first and second trimesters) to find out if your baby is at risk of birth defects.
While you can’t increase the number of eggs you’re born with, there are some influences that can impact the rate at which you lose them or the quality of your eggs. These include:
Knowing when the people in your family entered menopause may help you understand your fertility window and how many eggs you have. “Women who have mothers and sisters with premature menopause are at higher risk of losing more eggs because of genetic mutations,” says Dr. Sekhon. Premature menopause is when periods stop before the age of 40, or if they stop before 45, it’s called early menopause. If you’re concerned you might have a genetic predisposition that could impact your fertility, make sure to seek advice from a medical professional.
“Smoking can speed up the rate of egg loss,” says Dr. Sekhon. This is because the chemicals in cigarettes, including nicotine, cyanide, and carbon monoxide, accelerate egg loss. “There is also some evidence to show that excessive alcohol consumption can have a negative impact on the odds of conception and pregnancy,” says Dr. Sekhon. “How this happens is unclear, but studies have shown that an excess of two drinks per day or more than four drinks on a weekly basis is associated with lower rates of conception.”
It’s also believed that being underweight or obese can lead to irregular ovulation, but more research is needed to understand exactly how this can impact egg count.
“Treatments toxic to the ovaries such as chemotherapy and radiation can increase the rate of egg loss,” says Dr. Sekhon. “If women have surgery to remove ovarian cysts, this can also speed up the loss of eggs, as normal healthy ovarian tissue is sometimes removed.”
However, before undergoing any treatment of this kind, your health care provider should have talked this through with you to ensure you understand all the possible implications and to give you a chance to preserve your fertility if possible with egg freezing or embryo freezing.
A common misconception is that birth control (like the contraceptive pill) can alter the rate of egg loss, but this isn’t the case. What it does do, however, is lower your anti-müllerian hormone (AMH) levels, which are often measured to check a woman’s ability to get pregnant.
“Birth control does not impact egg count,” explains Dr. Sekhon. “Long-term use of estrogen-containing birth controls, such as the oral pill, vaginal ring, and contraceptive patch can create a false impression that your egg count is lower than it is, as it suppresses AMH levels and follicle counts [another means of measuring egg reserve] on a medical ultrasound.”
But these effects are only short term, and “can be reversed once the [contraception] is stopped.”
Dr. Sekhon adds: “We don’t tend to see these effects in hormonal IUDs [sometimes known as the coil] as they don’t contain estrogen and impact the AMH levels in the same way.”
If you’re feeling curious about your fertility, then knowing how many eggs you have available can be helpful. So, is it possible to find out?
“You can do an AMH blood test at any time during your cycle, whether you’re on or off birth control,” says Dr. Sekhon. An AMH blood test is a simple finger prick blood test that detects anti-müllerian hormone (AMH) in your blood. This hormone is made by developing eggs in your ovaries, and higher AMH levels suggest a bigger egg reserve.
“You can also test follicle count, using the follicle-stimulating hormone (FSH) on days 2 to 4 of the menstrual cycle,” she adds. This ultrasound procedure gives an idea of how hard the brain has to work to get the ovary to develop eggs in its follicles each cycle and can be used in conjunction with other tests (like the AMH one) to give a clearer picture of ovarian reserve. To find out more about this, “book an appointment with your OB-GYN [obstetrician and gynecologist] or a fertility doctor,” says Dr. Sekhon.
These tests are useful for understanding how you may respond to ovarian stimulation when undergoing IVF and how many eggs you may get from a retrieval. However, it’s important to know that AMH tests don’t always provide you with the full picture of your fertility, and some doctors don’t recommend doing them unless you’re having fertility treatment because they can lead to unnecessary anxiety.
Having a low egg count doesn’t generally influence your chances of conceiving each month, as Dr. Sekhon explains: “When you’re trying to conceive with a single ovulated egg, the odds of that egg resulting in a pregnancy have nothing to do with a low egg count and how many eggs are available in the ovary — it’s more related to the quality of that one egg.”
So try not to worry; if you have a lower egg count, but your egg quality is good, then you have as good a chance of conception as anyone else.
A low egg count is more relevant for anyone undergoing IVF to know. That’s because the process “tends to be more successful if you’re starting with a high number of eggs during the ovarian stimulation and egg retrieval process, as we can only develop the eggs that are available, and some are often lost along the way,” Dr. Sekhon says.
If you want to check your egg count by taking an AMH or FSH test, and you’re currently on hormonal birth control, then consult your OB-GYN first. They should be able to talk you through everything you need to know and help you going forward.
Incredibly, we are born with all the eggs we’ll ever have — and that’s a lot, somewhere between 2 to 3 million eggs. On average, women do have fewer eggs available for fertilization after the age of 35 — and the number of eggs declines year on year from this point until you reach menopause. But as we have learned, that doesn’t always mean your chances of getting pregnant are lower, as it’s the quality of the eggs that are generally more important than the quantity. And if you do happen to struggle with conceiving at any age, there are plenty of options available, from IVF to surrogacy and donor eggs/embryos.
If you’re unsure where you stand with your egg count and want to get a better picture, then have a conversation with a medical professional or your OB-GYN. That’s the best way of empowering yourself to make the choices that are right for your reproductive health.
Written by Stacey Carter