Why Does Egg Quantity Decline with Age?

Today, family planning is no longer just about “readiness.” It is also closely tied to biological timing, especially for women. One of the most frequently asked questions is: “Why does fertility decline as we get older?”

The key lies in both the quantity and quality of eggs

Every woman is born with a fixed number of eggs, and no new eggs are produced throughout life.

• During fetal development: approximately 6 - 7 million eggs

• At birth: approximately 1 - 2 million eggs

• At puberty: approximately 300,000 - 500,000 eggs

*From that point onward, the number of eggs continuously declines over time.*

Egg Loss Occurs Every Month - Even Without Pregnancy

In each menstrual cycle, the body selects a group of eggs to mature. However, only one egg typically ovulates, while the rest naturally degenerate. This means that egg loss occurs every month, regardless of whether pregnancy is attempted.

Increasing Age = Faster Decline in Egg Count

As a woman ages, the rate of egg loss accelerates significantly:

• Under 30 years old: Egg quantity and quality are generally optimal

• Ages 30 - 35: Gradual decline begins

• Age 35 and above: More rapid decrease in egg count

• Age 40 and above: Marked reduction in both quantity and quality

For this reason, age is one of the most critical factors in fertility planning. ⚠️ Not Only Quantity, but Quality Declines

Older eggs are more likely to have chromosomal abnormalities, which may lead to:

• Poor embryo development

• Reduced chances of successful pregnancy

• Increased risk of miscarriage

This is a major reason why fertility becomes more challenging with advancing age. With age, the ovaries become less responsive to hormonal stimulation, resulting in:

• Irregular ovulation

• Reduced response to ovarian stimulation (e.g., in IVF/ICSI cycles)

• Fewer eggs retrieved per cycle

How Can We Assess Ovarian Reserve?

A blood test measuring AMH (Anti-Müllerian Hormone) can help evaluate ovarian reserve (remaining egg quantity).

However, AMH does not reflect egg quality, so results should be interpreted alongside age and other clinical assessments by a fertility specialist.

Fertility Planning: What Are Your Options?

• If you are not yet ready for pregnancy, egg freezing (oocyte cryopreservation) is an option.

• If you have been trying to conceive without success, early consultation is recommended.

• Planning ahead at a younger age can significantly improve the chances of success.

Summary

Age plays a crucial role in female fertility. Women are born with a limited number of eggs, which gradually decline over time, along with their quality.

Understanding your reproductive health early can help you make informed decisions and plan your future more effectively.

 

 

Reference :

LRC Fertility Clinic Why Does Egg Quantity Decline with Age?

ArokaGo Providers LRC Fertility Clinic