When Does Fertility Begin to Decline?

A concern for many people as they get closer to 30 and beyond is when their fertility potential will begin to decline. In today’s society, age-related infertility is becoming more and more common because, for a lot of reasons, many people wait until their 30s to begin their families. So what does that mean for someone in their 20s who is trying to be proactive about their fertility? Let’s talk about it.

The truth about how age affects fertility

Even though people today are more conscious of their health and taking better care of themselves than ever before, improved lifestyle choices unfortunately can’t offset the natural age-related decline in fertility (the ability to get pregnant). Many studies have shown conclusively that the older you get, the more likely you are to have fertility problems when trying to conceive.

It’s important to understand that fertility declines as a woman ages due to the normal age-related decrease in the number of eggs that remain in the ovaries. It’s also important to understand that this decline may take place much sooner than some might expect.

How do you know if your fertility is declining?

You start life with a fixed number of eggs in your ovaries. As you get older, so do your ovaries and the eggs inside them. You can’t see or feel these changes but they are happening. Specifically, the number of eggs you have decreases as you get older and the eggs that are left become more and more likely to have abnormal chromosomes (mistakes in their DNA). In addition, you’re simply more likely to have developed health conditions that can affect fertility, like uterine fibroids.

A woman's peak reproductive years are between the late teens and in their 20s. 

For healthy women in their 20s and early 30s, around 1 in 4 women will get pregnant in any single menstrual cycle. By age 40, around 1 in 10 will get pregnant per menstrual cycle. A man’s fertility also declines with age, but not as predictably.

Is age 35 a fertility cliff?

Women are often told their fertility “falls off a cliff” at the age of 35 but is this really true? While 35 is an easy shorthand for the age of fertility decline, the real answer is a little more complicated than that.

Women are most fertile in their teens and early 20s, when they have about a 25% (1 out of 4) chance of getting pregnant naturally with each menstrual cycle. Fertility declines gradually throughout your entire adult life, so it’s actually happening even in your 20s. By the age of 30, the chance of natural pregnancy is about 20% per month, or 1 in 5. According to the American College of Obstetrics and Gynecology (ACOG), fertility starts to decline more significantly by age 32. This decline speeds up once you reach age 37 and by age 45, fertility has declined so much that getting pregnant naturally is unlikely for the average person.

The next question you might be asking is how much does fertility decline after 35? Let’s get into the two big factors that affect the decline of fertility with age: a decrease in the number of eggs and a decrease in the quality of eggs. The decline for both of these is much steeper after age 35-37. That’s why the impact of age-related fertility decline is talked about as being strongest after age 35.

Beyond this, there is also a higher risk with age of miscarriage, Down syndrome, and pregnancy complications. In a study that looked at over one million pregnancies, women older than 35 had a much higher rate of pregnancy loss—the risk of miscarriage over 35 was around 20%, over 40 was more than 50%, and by age 45, over 90% of pregnancies ended in miscarriage. Rates of Down syndrome increased significantly as well, from 1 in 1,200 for pregnancies at age 25 to 1 in 30 for those at age 45. 

So while 35 is not a cliff where our fertility suddenly plummets, it does make sense as a convenient shorthand.

What can I do to preserve my fertility?

Age-related fertility decline is a universal and consistent biological trait for all people–even men experience this, though the timeline is longer and less predictable. Unfortunately for everyone, this decline cannot be extended with supplements, diets, exercise, or other therapies. However, fertility decline can be worsened by certain lifestyle choices, like smoking. In other words, you can’t extend your fertility through lifestyle changes or good habits that are helpful to other areas of health—like your heart health—but you can make it worse. 

This is why egg freezing is such a powerful tool for people who want to preserve the option to have children later in life.

Get a fertility assessment 

Even if you’re not thinking about having babies for several more years, it’s important to know as much as you can about your fertility now. If you’re in your late 20s or early 30s, this is a great time to see your OB/GYN to discuss your future fertility and family goals A fertility assessment early on can alert you to any fertility issues—like an abnormally low egg count or a diagnosis like endometriosis– before they’re too late to manage. These assessments are pretty easy and typically just require an office visit, some bloodwork, and perhaps an ultrasound. 

Egg freezing

It’s important that all people, and especially those considering egg freezing, understand that fertility does not begin declining at age 35. Several studies have assessed people’s understanding of this topic and they’ve all concluded that most people don’t know the answer. For example, in a 2016 survey of 1,000 young men and women, more than 80% of all respondents believed women’s fertility only begins to decline after they turn 35. 

This misguided belief can leave people with fewer options, like adoption or egg donation, if they wait too long. While those are fantastic options for one person, they may not be for another person who wants a biological child. Egg freezing allows you to save your own eggs at a younger age for use at a later time when you’re ready–and it doesn’t affect your natural fertility! Unfortunately, many people don’t begin exploring egg freezing until they’re in their late 30s, at which point the fertility decline is already in full swing. 

So, if you have any desire to get pregnant in the future, consider freezing your eggs sooner rather than later, to really give yourself the best possible chance at a successful pregnancy. If you’re not sure where to begin with this process, start here.

Best age to freeze eggs

Since we know eggs are healthier and that there are more of them when you are younger, the best age to consider egg freezing is between ages 27 to 34—before age-related fertility decline has a significant impact. At that point, your fertility will still be highly intact, and what you’re able to preserve will be more likely to work for you in the future. In fact, studies like this one have shown that women under 35 have a significantly higher chance of freezing enough eggs in one cycle to give them a high chance of pregnancy later, than women who freeze their eggs over the age of 35.

Read more in What’s the Best Age to Freeze My Eggs?

How we can help!

If you decide to go through with egg freezing, Freeze by Co is here to help with our Split program, which allows those who qualify to freeze their eggs for free! In a Split cycle, you donate half of the eggs retrieved to a family that can’t otherwise conceive and freeze the remaining half for yourself. 

If you don’t want to donate, you can still participate in the Keep program, where you’ll be able to freeze your eggs and keep them all for yourself, on your timeline. In addition, you’ll have access to discounts throughout the process to lighten the financial load and our online support community. This valuable resource lets you engage with other people freezing their eggs at the same time! 

Whatever you choose, our team is here to support you as you find the best family-building option for you.