One of the most surprising things people first learn about in biology class is females have a limited fertility period. Males produce sperm throughout their entire lives; although females produce multiple eggs, they eventually become infertile as they age. One of the factors affecting female fertility is the ovarian reserve, which is the number of eggs, especially healthy eggs, their ovaries contain. For women interested in having children, the next question becomes apparent: how many eggs does a woman have?
A woman has the most number of eggs during birth when her ovaries contain at least a million egg cells. Even before birth, a female fetus in their mother’s womb has millions of eggs. However, only around 300,000 usually remain once puberty starts. By the time the woman reaches menopause, the average women has roughly a thousand eggs remaining. To understand why this decrease occurs and how it impacts fertility, you must first understand how the female reproductive organs work during each menstrual cycle.
The Menstrual Cycle Of Women Eggs
Every monthly cycle, an interplay between several hormones leads to changes in the structure and function of several reproductive organs. A woman’s menstrual cycle is involved in preparing the woman for a possible pregnancy. “The menstrual cycle has one purpose and one purpose only: reproduction,” Lauren Streicher, M.D. , associate professor at Northwestern University Feinberg School of Medicine adds.
The menstrual cycle starts on the day of ovulation, which is when an egg cell is released from one of the ovaries. Ovulation is accompanied by a spike in estrogen, which is used to trigger the ovaries into releasing the egg. Progesterone also spikes, signaling the lining of the uterus to thicken and prepare for implantation of a fertilized egg. Roughly two weeks after ovulation, this lining will shed away if the egg cell was not fertilized by a sperm. Levels of both hormones drop, leading to menstruation.
On the first day of menstruation, the pituitary gland starts to secrete follicle-stimulating hormone. Also known as FSH, the hormone is responsible for helping several follicles in the ovaries to mature. Each follicle contains an immature egg cell which is developed further by FSH.
Of the stimulated follicles, only one egg reaches maturity and is released during ovulation. An article by Nicole Galan, RN, points out that “Every month, the body selects a cohort or group of eggs as “contenders” to ovulate. One egg will ultimately become the dominant follicle. The follicle contains the one egg that’s ovulated that month and represents your one chance to conceive.”
The other stimulated follicles die in a process called atresia because FSH levels drop gradually on the days preceding ovulation. The dominant follicle becomes sensitive to FSH and can continue developing despite the drop in hormone levels. As a result, the egg count of each ovary decreased with each menstrual cycle.
Follicle Development
The story of egg cell development and women’s fertility goes beyond the menstrual cycle. As mentioned before, the ovaries contain all the egg cells the woman will have for her entire life, and women cannot create new egg cells after birth. These egg cells are inactive to help with fertility preservation, and will help preserve them until needed.
According to Yasmin Gosiengfiao, MD and co-author, “The initial number of follicles in humans is established in utero at 5 months gestation with approximately 10 million primordial follicles. This number of follicles diminish in utero and after birth to nearly 500,000 at menarche and continue to decline thereafter.”
Egg cell development starts when around 30 ovarian follicles, originally microscopic, begin to grow. During this time, each follicle is insensitive to hormones. They steadily grow in size for the next three months, eventually becoming fluid filled sacs. When they reach around a few centimeters in size, they develop to antral follicles. At this point, they become sensitive to FSH, and the next hormone surge spurs them to mature.
Only one of these follicles reach peak maturity, and it is responsible for releasing the egg cell during ovulation. Because of this process, an average of 30 follicles is lost by each woman every day. Lost eggs are not replaced.
Trends in Ovarian Reserve
The ovarian reserve can answer the question of how many eggs does a woman have. The term refers to the total number of eggs contained in the ovaries. It starts to drop after birth, even before the woman reaches puberty, as some of the dormant follicles age and die. Adolescence triggers a faster drop, and the rate of depletion continues to accelerate until the woman reaches menopause.
Interestingly, the number of antral follicles produced per cycle decreases with age. For women near menopause, gynecologists can only detect around 10 antral follicles. However, egg count continues to drop as more and more cells expire.
Ovarian reserve correlates with fertility and age. As it drops, a woman becomes less fertile. Even before menopause, women start to lose potency as they reach their thirties. Many women become infertile once they reach their mid-forties. However, individual differences mean exceptions can occur, such as older women who can continue to bear children.
Measuring Ovarian Reserve
There are two main types of approaches to human ovarian reserve testing. The first approach measures hormone levels through a blood test, while the other method directly counts the number of follicles in the ovaries to determine egg quantity.
You can try two hormones tests. The first involves measuring levels of FSH in the blood during the first day of menstruation, the release of which is stimulated by a different chemical, the gonadotropin releasing hormone. The first method is based on the interplay between the pituitary gland and the developing follicles. If there are fewer developing follicles, they signal the pituitary gland to produce more FSH to compensate. Higher FSH levels, and to a degree, luteinizing hormone (LH) can indicate fewer eggs.
The other hormone test focuses on the amount of anti-mullerian hormone (AMH) circulating in the blood to determine total egg count. AMH is a protein hormone produced by specific follicle cells. Follicles release AMH, so higher AMH levels indicate more eggs. Unlike the FSH test, the AMH test is a direct measurement of ovarian reserve. The AMH test is also more sensitive so it is useful for early detection of any fertility problems.
A transvaginal ultrasound is a direct method for measuring egg count. The gynecologist inserts a probe into the vagina directing it towards the ovaries, allowing the operator to visually take the antral follicle count. Less developed follicles do not show up on the screen, so the only visible follicles are the developed ones.
The ultrasound test allows the physician to see the number of follicles that will respond to hormones during the next menstrual cycle. However, this test is subjective, as it relies on visual inspection to measure egg count.
Knowing how many eggs does a woman has is useful in assessing the fertility of a woman, both in the present and in the future. The concept of ovarian reserve gives people an indicator of how much time a woman has before she becomes infertile.
How Many Eggs Does a Woman Have FAQs
How many eggs are left at age 30?
On average, 1,000 eggs die every month. Only one from the thousand ovulates. By the average age of 30, egg cells have significantly decreased in most women. Around 90% of eggs are lost by the age of 30.
How many eggs does a woman lose during her period?
Before puberty, about 11,000 eggs die each month, but once puberty begins, only a thousand eggs die monthly. During period one of the eggs released will become the dominant egg. It will ovulate and live for the next 24 hours to be fertilized.
Can a woman run out of eggs?
Yes. As a woman ages, more eggs start to become unusable for pregnancy. Menopause is when a person stops ovulating and ovaries cease to produce specific hormones. During this time, women will be unsuitable for pregnancy. Nutrition and other factors can cause menopause earlier or later.
At what age do women’s eggs go bad?
Fertility for women decreases by the age of 30 and more rapidly by the age of 35 due to having fewer eggs. However, women can still get pregnant naturally at this age, only that the chances get slimmer. Fertility treatment can prolong the lifespan of eggs. Alternatively, egg donation can allow you to get pregnant later in life. Freezing eggs at sub zero temperatures can also preserve them for the future, ready to receive a donor’s sperm.
What is the best age to have a child?
Assuming normal ovarian function and no premature menopause, fertility for both men and women is at a peak at around 20s. If you are planning to build a family, age 20 is the time to begin having a baby for a higher chance of bearing a healthy child. At age 35-40, fertility decreases significantly. Seeking fertility care can improve fertility rates later in life. Alternatively, if you would prefer to get pregnant at an older age, birth control is also an option.
What is the maximum age for a woman to get pregnant?
It varies among women. Nutritional supplements, reproductive medicine, and hormone therapy may allow a woman to stay fertile for longer. There are fertile women who were able to carry a child even in their 40s or 50s. Some women may experience early menopause and become infertile at an earlier age. Furthermore, there are more risks for both the mother and the baby in late pregnancy.
Can a 7-year-old get pregnant?
No, a woman can only get pregnant if she’s ovulating. A 7-year-old will not have a mature egg available. Ovulating only begins around a year after the first period and the first menstrual cycle occurs at least at age 11.
Is 50 too old to have a baby?
Women can still have a baby at age 50 although the risk is higher. There is an increased chance of premature birth, low birth weight, fetal mortality, and small size for gestational age. Egg freezing may be a good option if you plan to have a baby girl or boy at an older age, along with in vitro fertilization using her own eggs. Surrogacy or using donor eggs is also an option.
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