Why don’t eggs hatch?

In this brief guide, we will answer the question, “why don’t eggs hatch,” and discuss whether it can take longer than twenty-one days for the eggs to hatch, and what causes chicken eggs to hatch late.

Why don’t eggs hatch?

Eggs don’t hatch because of temperature fluctuations and humidity. 

When we think of an egg hatching, we think of the adorable little chick emerging from its shell with a triumphant, beak-first waddle across the floor. Unfortunately, this isn’t always the case. 

Poor results in hatching are commonly caused by the improper control of temperature and humidity. When the temperature or humidity is too high or too low for a long period of time, the normal growth and development of the embryo is affected.

When an egg does not hatch, it means that the fetus did not develop properly, and there were no circumstances for the chick to be born. In other words, there is nothing to worry about: a healthy bird lays eggs that do not allow for hatching; an unhealthy bird cannot even lay eggs in the first place.

There are several reasons why an egg might fail to hatch:

-the embryo was unable to grow properly because of a genetic defect;

-the embryo died before it could fully develop;

-the embryo died while it was developing;

-an infection inside the egg caused the embryo’s death;

-a female chicken got too old and her ovaries stopped producing fertile eggs.

What happens if an egg does not hatch?

If an egg fails to hatch, the farmer has to determine why.

There are two main reasons for failure: infertility and embryo mortality. Either one of these conditions can be diagnosed during candling. If a chick embryo is dead, it will not move or react to the light. If there is no embryo at all, the air chamber will be empty.

What causes chicken eggs to hatch late?

For many reasons, chicken eggs will not hatch on time. One of the most common causes is a high level of humidity. In this case, the embryo will not develop properly, and will not be able to break through the eggshell to hatch.

The factors that determine when an egg hatches include:

1. The temperature of the air and nest

2. The size of the hen’s body, as measured by her girth

3. The number of hours per day that she sits on the nest

What causes chicken eggs to hatch late?

Hence, factors such as high humidity or low temperature can cause early or late hatching. Hatching is a process in which the chick develops inside the egg and hatches from it. It is initiated by a hormone called chorioallantoic acid (CAA), which is produced by the embryo.

CAA stimulates the albumen to absorb water from the air so that the eggshell becomes porous and air enters the egg. The embryo then starts drawing in air through this pathway, using it for its respiration.

In order to avoid suffocation, moisture must evaporate from the embryo’s respiratory tract at a rate that matches its production. This requires an adequate supply of oxygen and an efficient respiratory system. If oxygen levels are too low, abnormal heart rates and poor growth occur, while higher levels cause oxidative stress, leading to cell death and organ failure.

The oxygen concentration within an egg is controlled by four factors: carbon dioxide concentration; air flow rate; relative humidity; and albumen thickness. Carbon dioxide is produced by the embryo during respiration and accumulates in the albumen until it reaches equilibrium with the outside environment. 

Can it take longer than twenty-one days for the eggs to hatch?

Yes, it is possible for eggs to take longer than 21 days to hatch. It is possible for fertilized eggs to hatch before 21 days, but typically it will take between 21 and 26 days for the chicks to emerge fully from their shells.

Most chicken eggs will hatch within twenty-one days of incubation, but it is not a guarantee. 

Various factors, like the age of the eggs, the health of the mother hen, and fluctuations in temperature may result in some chicks hatching before day 21 and others taking more time than twenty-one days.

If you have fertilized the eggs and chilled them prior to setting them in an incubator, the process might take a little longer. Don’t give up on your chicks until they have been in their incubator for at least 26 days.


In this brief guide, we have addressed the question, “why don’t eggs hatch,” and other questions related to the questions such as can it take longer than twenty-one days for the eggs to hatch, and what causes chicken eggs to hatch late.



Hi, I am Charlotte, I love cooking and in my previous life, I was a chef. I bring some of my experience to the recipes on this hub and answer your food questions.