Why is maternal age so important?
Age is the biggest factor affecting egg supply. This is true for all women: the older you get, the fewer eggs you have. Your body does not produce more eggs, nor is there any available treatment to increase the quantity or quality of your egg supply.
Even though statistical trends have shown that the age of women at the birth of their first child has steadily been on the rise since the mid-1970s, a woman’s fertility peaks in her mid-20s, begins to decline around 27, and drops off more steeply after age 35. A woman’s fertility is measured by her ability to achieve a pregnancy on a given month. For women, the ability to conceive is tied to the quality of her eggs. As women age, hormonal changes begin to take place. There is a lot going on but of particular interest are the two main hormones controlling the development and release of the egg each month. These are follicle-stimulating hormone (FSH) and lutenizing hormone (LH).
A rising FSH level is linked to a decreasing egg quality. Decreased egg quality means it becomes more difficult for the sperm to fertilize the egg naturally. There may even be chromosomal abnormalities occurring within the egg itself, which is why we recommend an amniocentesis for pregnant women over 35.
Another factor to consider is the number of eggs. As a woman ages, the number of eggs in her ovarian reserve continually declines. Women are born with their lifetime supply of eggs—generally around 1 to 2 million. By the time a woman reaches menopause, typically in her early- to mid-50s, as many as a few hundred remain, potentially even less.
To illustrate this point, the natural pregnancy rate for women older than 30 is 20 to 30 percent per month but by age 40 the likelihood of conception occurring naturally drops to less than 5 percent per month.
Did You Know?
You can ask your doctor to check your egg supply during a routine OB/GYN exam. Regardless of your age, you can request ovarian reserve testing, which is often covered by insurance, during a regular, annual visit to your obstetrician/gynecologist. This can help women proactively plan for the future and serves as a baseline for future comparison.