How many eggs do women have?

VnExpress•26/09/2023

Women are born with approximately 6 million eggs in their ovaries, losing thousands each month, and by menopause, they have fewer than 100 eggs left.

From birth to puberty

Each girl is born with a certain number of eggs, and no new eggs are produced throughout her life. At this stage, the eggs are immature and are called oocytes (ovums). These oocytes are located in follicles (fluid-filled sacs) within the ovaries. As they grow, they become oocytes and develop into mature eggs, or ovums.

During the early stages of fetal development, a baby girl's ovaries contain approximately 6 million eggs. This number gradually decreases until the child is born, leaving 1-2 million. egg.

Menstruation only begins in girls at puberty, about two years after breast tissue appears. At that time, the hypothalamus in the brain begins producing gonadotropin-releasing hormone (GnRH). GnRH stimulates the pituitary gland to produce follicle-stimulating hormone (FSH). FSH initiates egg development and causes estrogen levels to rise. The average age for menstruation is around 12 years old, but some girls may start as early as 8 years old.

During puberty, each girl only has about 300,000-400,000 eggs . This decline is due to more than 10,000 eggs dying each month before puberty.

As ovarian follicles mature, they become sensitive to hormones during the menstrual cycle. Each month, the body selects a group of mature eggs to release, but ultimately only one egg is released, representing a woman's unique chance of conception each month. In some exceptional cases, more than one egg is released, leading to twins.

All the remaining eggs in that cycle shrink and die. This happens monthly and continues until a woman reaches menopause, at which point she no longer has eggs.

The number of eggs that die each month decreases after puberty. According to infertility specialist Dr. Sherman Silber in the US, a woman loses approximately 1,000 immature eggs each month after the start of her menstrual cycle. Research data has not yet clearly determined whether health status and diet affect the quality or quantity of egg cells. According to a 2018 study by the American Society for Reproductive Medicine, smoking and certain chemotherapy and radiation treatments may increase the rate of ovulation.

Women's fertility is at its best between the ages of 20 and 30, when both the quantity and quality of eggs are high. (Image: Freepik)

From age 30 and above

According to the American College of Obstetricians and Gynecologists (ACOG), fertility begins to decline rapidly in women as they reach their 30s. By age 40, the egg supply is less than 10% of what it was before birth. Research indicates that premenopausal women over 40 have less than a 5% chance of getting pregnant during each menstrual cycle.

When the supply of eggs runs out, the ovaries stop producing enough estrogen, and women experience menopause. The exact timing of menopause depends on the number of eggs a woman is born with and the rate of ovulation. The average age for menopause, when menstruation stops, is 51. In some women, menopause may occur earlier or later.

According to data from the American College of Obstetricians and Gynecologists (ACOG), by age 37, women will have only 25,000 eggs in their ovaries, and menopause will occur approximately 15 years later. At that point, they will have fewer than 100 eggs.

The most important factor determining egg quality is age. As women age, both the quantity and quality of eggs decrease. Just before ovulation each month, eggs begin to divide. Older eggs are more prone to errors during this division process, making them more likely to contain chromosomal abnormalities. When the egg and sperm combine to form an embryo, the risk of chromosomal abnormalities or genetic defects is higher. This is why older women have a higher risk of giving birth to children with birth defects.

If born with a large number of eggs, women can still conceive naturally in their mid-40s or even late 40s. Those in their 30s who ovulate faster due to certain risk factors may experience early menopause or premature ovarian failure.

If concerned about ovarian reserve or egg quality, women should see a doctor for examination and assessment of risk factors, and for advice on treatment methods. If planning to have children later in life, you may consider freezing your eggs. The earlier you freeze your eggs, ideally before age 35, the higher the quality of the eggs, the greater the quantity retrieved, and thus the higher your chances of conceiving.

Anh Ngoc (According to Healthline )

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