what happens to eggs as they age

Quick Scoop

As eggs age, both their quantity and quality decline, and the risk of chromosomal abnormalities goes up. In practical terms, that means older eggs are less likely to be fertilized successfully and more likely to lead to miscarriage or pregnancy complications.

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What changes	What it means
Egg number drops over time	People are born with a finite egg supply, and many eggs are lost naturally before ovulation even starts.
Egg quality declines	Older eggs are more likely to have genetic or chromosomal errors, which lowers the chance of a healthy pregnancy.
Fertility can fall faster after 35	Sources note that egg loss and quality decline accelerate after about age 35, reducing the odds of conception.

A simple way to think about it is that eggs do not just “run out”; they also become less reliable with age, even before menopause. Research also suggests human eggs can stay in the ovaries for decades, but their internal maintenance systems still change over time, which may contribute to age-related fertility decline.

TL;DR: eggs age by becoming fewer, more error-prone, and less likely to produce a healthy pregnancy.