how does age affect fertility?

You may think of yourself as a fit, healthy and energetic woman, with no concerns about getting pregnant in your mid- to late 30s or early 40s. And all of that will help boost your chances of a healthy and positive conception. But despite your good health and well-being, at 35 years or older you are considered of “advanced maternal age” by the medical profession.

age and the ova

How does age affect fertility in women? Your fertility potential declines with age. That’s because all the eggs (ova) you will ever have available to make a baby are already formed at the time of your birth. Before you are even born, the number of eggs peaks at over a million. At birth, this number has already declined to about 300,000 eggs, which is maintained until puberty. Of the eggs remaining at puberty, only about 300 will be ovulated during your entire reproductive years.¹ So as you age, so do your 300-odd eggs that are available for fertilization.

Over time, your eggs become more fragile and their genetic material incurs more damage. This inevitable increase in fragility is what accounts for the greater risk of genetic abnormalities with age. But it also leads to greater rates of missed ovulations and miscarriage, making conception more challenging. Couples older than 35 may take twice as long to conceive as a younger couple because of the declining number and quality of eggs and because ovulation is less frequent.

Why is 35 the magic year everything changes? It isn’t, but 35 is used as the approximate age at which the risk of having a baby with a genetic disorder (such as Down syndrome) exceeds the risk of miscarriage if you are tested for such disorders (such as with amniocentesis). Simply put, 35 is the approximate age at which prenatal genetic testing becomes worth the risk.

age-related health problems in women

Aside from the increasing fragility of ova, a woman’s age and fertility are connected in other ways. Older women also have a greater likelihood of health problems, including those that may affect their reproductive potential:

• Infection or surgery that caused scar tissue around the fallopian tubes or cervix
• Endometriosis, in which tissue attaches itself to the ovaries or fallopian tubes, hampering conception
• Fibroids or uterine disorders
• Decrease in cervical fluid
• Chronic health problems such as high blood pressure or diabetes

If you’ve maintained a healthy lifestyle over the years, you improve your odds. But the natural effects of age on fertility cannot be offset entirely by improved health in later years.

age and the sperm

The story of age and fertility is different for men than women because, unlike eggs, sperm are constantly being replenished. Sperm does not become as fragile as a woman’s eggs with age, but they do undergo changes. As men age, their testes tend to get smaller and softer, and the sperm’s shape and motility (movement) tend to decline. There is also a slightly higher risk of genetic defects in the sperm of older men.

age-related health problems in men

Aging men may develop medical illnesses that impact their sexual and reproductive function, such as high blood pressure and diabetes. And of course decreasing interest in, or ability to have, sex will affect fertility rates. Not all men experience reproductive or sexual challenges as they age, especially those who maintain good health over the years. It is also reassuring to know that just as modern medicine offers fertility support to women, men also have many good options when they need reproductive assistance.