We believe every woman deserves the facts about her biological clock. Start here to learn more about fertility and age and how time really affects your ability to have a healthy baby.
(And if you’re ready to get proactive about your fertility future, you can schedule a fertility assessment today to test your ovarian reserve and understand how egg freezing can help.)
It’s a common misconception that we have a 100% chance of pregnancy each time we ovulate (i.e., each month). Because a certain percentage of our eggs are abnormal at any age, and because fertilization has to happen within a narrow window after ovulation occurs, even a young, healthy woman trying to get pregnant has only about a 25% chance each month.
However, we get 12 or so cycles a year—so a healthy woman in her 20s has a very good chance of getting pregnant in a given year, if she’s trying. (That’s why doctors tell women under 35 to try for a year before seeking fertility help.)
Our “reproductive life” begins when we get our first period, usually around age 12 or so, and lasts until our last menstrual period some four decades later (that’s menopause). But because egg count and egg quality decline as we age, we don’t remain fertile for the entirety of this timespan.
No, it’s not like our fertility drops off a cliff at age 35; fertility decline happens throughout our adult lives. But fertility decline is a snowball effect—meaning as we age, not only does our fertility decline, but the rate at which it declines actually increases. So the downward slope of fertility and age gets steeper in our mid-30s. Thanks biology!
The truth about natural fertility and age: while women under 30 have about a 25% chance of getting pregnant naturally each cycle, that chance drops to 20% for women over 30, according to estimates by the American Society for Reproductive Medicine. By 40, the chance of getting pregnant naturally each month is just 5%.
In fact, the above picture of age-related fertility decline is reflected in many studies of assisted reproductive technology.
One study of healthy, fertile women undergoing artificial insemination with donor sperm indicates that the chance of getting pregnant in 12 cycles (or about a year) was 73% for women 30 and under, and dropped to 54% for women over 35.
And national statistics for women undergoing in vitro fertilization using their own eggs of the same age demonstrate that the drop in IVF success is also dramatic: for women under 35, the percentage of successful IVF cycles was 41.5%; for women 35–37, it was 31.9%; for women 38–40, 22.1%; 12.4% for women 41–42; 5% for women 43–44; and just 1% for women over 44. That means that, after age 35, IVF birth rates declined about 10% every 2 years—reflecting a similar relationship between fertility and age as we see in natural fertility.
(We’re not trying to be scaremongers! But it’s really important that women have all the facts about fertility and age, so they can make informed choices about their lives and their health.)