How Age Affects Fertility (And What You Can Still Control)
When it comes to getting older, even though everyone will eventually run out of eggs, we are all on very different timelines. But here’s the part that surprises most people: running out of eggs is not usually what limits our ability to get pregnant as we age. The bigger issue is egg quality. And while “quality” gets thrown around a lot in fertility, I actually like to take a step back and think about egg quality in two distinct ways—because both matter.
What We Mean When We Talk About Egg Quality
Most of the time, when fertility doctors talk about egg quality, they’re referring to genetic normalcy, or whether an egg has the correct number of chromosomes.
And yes, genetics is a huge part of egg quality. As we age, our eggs have been inside our bodies longer, absorbing the wear and tear of the world around us. This is why age is such a strong predictor of chromosome abnormalities, and why it’s one of the hardest factors to overcome.
I like to explain chromosomes this way:
Imagine your chromosomes are a line of kindergartners standing in perfect alphabetical order. The longer I ask them to stand there, the higher the odds that someone is going to get out of line. And the more distractions I add—puppies, candy, chaos—the more likely it is that they’ll wander.
Those distractions? That’s inflammation.
This is why age matters, but it’s also why age is not the only factor that contributes to genetic normalcy.
The Metabolic Side of Egg Quality We Don’t Talk About Enough
In addition to genetics, we cannot ignore the metabolic importance of the egg.
Your egg has a massive job. It contains mitochondria and must:
Accept a sperm
Support fertilization
Drive embryo development for the first several days
In fact, the male genome doesn’t even turn on until around day three. Until then, everything depends on the egg’s ability to divide normally and function well.
This means egg metabolism matters—and this is where lifestyle, inflammation, and overall health play a much bigger role than many people realize.
This is also where I sometimes see fertility medicine become overly dismissive, with statements like:
“You’re older. There’s nothing you can do about egg quality.”
While it’s true that we cannot undo age-related genetic changes, we absolutely can control inflammatory and metabolic factors that affect how well eggs function.
Why Even Genetically Normal Embryos Don’t Always Work
Here’s an important reality check:
Even when we have a genetically normal embryo, the live birth rate is only about 65–70%, even in the best labs, under the best conditions.
Why isn’t it 100%?
I call this embryo competency—or metabolic health. It shows us that structure, cellular function, and environmental exposures still matter. What we expose our eggs, sperm, and embryos to plays a real role in whether a pregnancy results in a baby.
This is why we shouldn’t be dismissive of lifestyle factors, especially as we get older.
What Actually Changes After Age 35
Two important things happen as we age—and they happen at the same time:
Egg genetics decline
Around age 35, about half of eggs are genetically normal, and half are abnormal
After 37, the majority of eggs are genetically abnormal
Egg number declines
We have fewer eggs to work with
Even with IVF, we can only grow the eggs that are already available
Add in increased inflammation and less optimal metabolic health, and fertility becomes more challenging.
This is why:
At age 30, the chance of pregnancy per month is about 20%
At age 40, it drops to around 5% per month
And miscarriage rates rise dramatically:
~20–25% at age 30
40–50% over age 40
This combination leads to a much lower overall chance of live birth.
Why Understanding Your Data Matters
This is why knowing your ovarian reserve and understanding egg quality is so important—especially if you’re waiting to get pregnant.
IVF does not always work. But there are ways to improve the odds, and those decisions should be based on data you understand, not fear or assumptions.
You cannot make informed choices with information you don’t have.
A Story That Highlights Why One Number Doesn’t Define You
I once saw a 32-year-old patient who had been on birth control for over six years due to irregular bleeding. No clear cause was ever identified. When she stopped taking the pill to try to conceive, her period never returned.
Testing revealed:
Undetectable AMH
An antral follicle count of one
She was told donor eggs were her only option.
When she came to me for a second opinion, the data was accurate—but the conclusion wasn’t the full story. She was young, meaning her egg genetics were still favorable. Further workup revealed autoimmune thyroid disease, which was contributing to inflammation and ovarian dysfunction.
We treated the underlying issue, addressed inflammation, and moved quickly to IVF.
Her results:
Cycle one: 3 eggs → 2 genetically normal embryos
Cycle two: 2 eggs → 1 genetically normal embryo
She now has her first baby and two embryos frozen for the future.
She was never guaranteed success. But she was given the opportunity to choose, with honesty and transparency.
You Are Not Your AMH
Ovarian reserve matters, but it is not everything.
You are not defined by:
One lab value
One clinic’s opinion
One conversation
If someone gives you information that doesn’t make sense, you deserve explanations. And if those explanations aren’t clear, you deserve a second opinion.
This is your life. Your family. Your future.
My job isn’t to promise outcomes—it’s to give you the data, explain the reality, and help you make the decision that feels right for you.
