Hello, my loves. Welcome back to the Love & Science podcast.

Today we’re talking about a foundational topic in reproductive medicine: what truly drives ovarian aging.

This matters because fertility is directly tied to both egg number and egg quality — and both decline over time.

We are born with all the eggs we will ever have.

At birth, it’s estimated that we have about one million eggs.

By menopause — typically around age 50 to 51 — that number declines to about one thousand.

What many people don’t realize is that egg loss begins even before birth. During fetal development, we actually have more eggs than we’re born with. Egg decline is happening from the very beginning of life.

So when we talk about ovarian aging, we’re really talking about two things:

• Egg number

• Egg quality

Egg Quality: The Energy Behind Life

Egg quality is about whether an egg can properly complete cell division and create a healthy embryo.

Each egg must divide its chromosomes precisely — ending with 23 chromosomes. When fertilized by sperm (also contributing 23 chromosomes), that creates a healthy embryo with 46 chromosomes.

That process requires enormous cellular energy.

For years, fertilization failure was often blamed primarily on sperm. But we now understand that in many cases, fertilization issues reflect insufficient egg energy.

The egg’s mitochondria — the energy-producing structures — power:

• Chromosome alignment

• Meiosis and mitosis

• Early embryo cell divisions

• DNA recombination

If that energy is compromised, embryo development may stall early.

Egg energy is foundational.

Egg Number: Ovarian Reserve

Egg number is typically measured through Anti-Müllerian Hormone (AMH).

AMH peaks in our mid-20s and gradually declines over time.

Some women have lower egg reserve at a young age but still have good egg quality. Others may have a higher number of eggs but poorer quality due to age.

Ideally, fertility is strongest when both egg number and egg quality are high.

But age affects both.

What Drives Ovarian Aging?

1. Genetics

Genetics is the strongest factor.

If a woman’s mother experienced early menopause, that pattern often repeats. I frequently see sisters with similar fertility timelines.

We cannot change our genetics — but we can influence other variables.

2. Smoking

Smoking is clearly harmful to egg health.

Studies suggest smoking can age eggs by approximately five years. A 37-year-old smoker may have egg quality closer to that of a 42-year-old.

Smoking also lowers AMH and impacts egg number.

3. Diet and Antioxidants

Egg quality is strongly linked to mitochondrial function.

Mitochondria are sensitive to oxidative stress, and antioxidants support their function.

Diets rich in:

• Fruits and vegetables

• Whole foods

• Natural antioxidants

• Vitamins and minerals

are associated with better reproductive outcomes, particularly in women with PCOS.

CoQ10 — an antioxidant supplement — has shown benefit in supporting egg energy at the mitochondrial level.

While more IVF-specific data is emerging, dietary quality absolutely matters.

4. Body Weight and Inflammation

Higher BMI and chronic inflammation can impact ovarian reserve.

I’ve seen women with low AMH improve their levels after significant weight loss and metabolic optimization.

Inflammation affects ovarian signaling and may accelerate aging processes.

5. Environmental Toxins

Emerging research links endocrine-disrupting chemicals to earlier menopause and impaired egg quality.

These include:

• Plastics

• Certain cosmetics

• Pollutants

• Environmental toxins

Exposure over time may contribute to reproductive decline.

Simple changes — such as using glass or stainless steel instead of plastic — can reduce exposure.

Women living in highly polluted urban environments may also experience reduced egg quality.

6. Oxygen and Sleep

Eggs require oxygen for optimal function.

There is growing research connecting obstructive sleep apnea to poorer IVF outcomes.

When oxygen levels improve, IVF outcomes sometimes improve as well.

This suggests oxygenation plays a role in egg health.

The Cellular Mechanisms Behind It All

At a deeper biological level, ovarian aging involves:

• DNA damage

• Telomere shortening

• Reactive oxygen species

• Mitochondrial dysfunction

These molecular processes are influenced by genetics, environment, diet, and metabolic health.

We are still uncovering the full picture.

Can Ovarian Aging Be Slowed?

Age remains the strongest predictor of egg quality.

That is consistent and well-supported.

However, there are areas within our control:

• Avoid smoking

• Optimize diet

• Maintain metabolic health

• Reduce toxin exposure

• Address sleep apnea

• Support mitochondrial health

Emerging therapies like ovarian PRP and rapamycin are being studied, but research is ongoing.

The key takeaway:

We are born with all the eggs we will ever have.

What our bodies experience over our lifetime, our eggs experience too.

Ovarian aging is complex.

We are still learning.

But understanding the difference between egg number and egg quality — and recognizing the modifiable factors — gives us agency.

My commitment to you is to stay current on the research so that we can continue making evidence-based decisions that lead to the best possible outcomes.

I love you, and I’ll see you next time.