When Babies Develop Eye Color: Eye Color Changes & More

Eye color reaches permanence within the first year of birth, although some babies’ eye color can change up to the age of 3. Subtle changes in color can occur up to 6 years old.

Generally, a child’s eye color is not “set” until 9 to 12 months old.  

A study conducted by Stanford University asserts that iris color in newborns is brown the majority of the time (63 percent of study participants), while around 20 percent have blue eyes and around 5 percent have green or hazel eyes. Around 9 percent of infants have indeterminate eye color.

When Do a Baby’s Eyes Change Color?

Pigmentation of the iris is what causes a baby’s eyes to change color. This process occurs during the first year of infancy. In many cases, if a baby’s eyes are brown, they will remain so, but there are exceptions to this general rule.

Eye color can continue to change after the first year of life, though these changes are less common. Subtle color changes may occur in children up to the age of 6. 

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Why Is Eye Color Important?

Certain features are more noticeable than others. A baby’s eye and hair color are among the most noticeable features, which is why eye color is often of such importance to parents.

Recent studies have suggested that eye color and eye size may affect perception of cuteness in babies. For many people, eye color is a strong determining factor in the overall perceived cuteness of a baby.

What Causes Different Eye Colors?

A baby’s eye color ends up being determined by genetic variations. There are specific genes that are associated with eye color — genes that are involved in melanin production, transport, and/or storage. 

Eye Color Is Related to Melanin

When it comes down to it, a baby’s eye color is going to be related directly to how much melanin is located in the iris’s front layers. Brown eyes have more melanin than blue eyes, for instance. Green eyes are genetic mutations and have slightly more melanin than blue eyes.

Just as skin darkens from exposure to daylight and bright artificial lights, eye color becomes browner. Once the eye is exposed to light, melanin production cannot be reversed, meaning brown eyes cannot change to blue eyes if exposure to light is avoided.

Eye Color Is Related to Genetics

Parents pass on one copy of their eye color genes to a child. Brown eyes are generally dominant to blue, meaning that babies who have genes for brown and blue will most likely end up having brown eyes. Parents who both have blue eyes tend to have babies with blue eyes.

What Causes a Baby’s Eye Color to Change?

Melanin develops in the eye when melanocytes in the iris respond to light exposure. This causes melanin secretion. 

Melanin develops mostly during the first 6 months and tends to wane around 9 months of age. Melanin production usually concludes around the end of the first year of infancy.

When Is a Baby’s Eye Color Permanent?

Right around the end of the first year of life is when a baby’s eyes will generally be their permanent color. However, eye color for some babies can continue to change for up to 3 years.

Again, subtle changes in eye color can happen for up to 6 years. In such cases, green irises can turn to hazel. Hazel may also turn to a darker brown color.

Scientists are currently working on ways to predict eye color through DNA testing. Currently, there is no way to reliably predict which color a baby’s eyes are going to be, although it’s generally safe to play the percentages. 

For example, parents who both have blue eyes have around a 99 percent chance of having a baby with blue eyes. If both parents have green or brown eyes, there is a 99 percent chance the baby will have the same eye color as the parents. 

When Do a Baby’s Eyes Stop Changing Color?

It’s safe to say that a child’s eye color has reached permanence by the age of 6 years old. 

Although the genetic architecture of eye color may be a complicated one, parents can usually tell what color their child’s eyes will be around the first year mark. It’s unlikely, though not impossible, that a child’s eyes will change color beyond that point. But any changes beyond 1 year old will be subtle.

References

1. Eye Size Affects Cuteness in Different Facial Expressions and Ages. (January 2022). Frontiers in Psychology.

2. What Colour Are Newborns’ Eyes? Prevalence of Iris Colour in the Newborn Eye Screening Test (NEST) Study. (April 2016). Acta Ophthalmologica.

3. Investigating the Genetic Architecture of Eye Colour in a Canadian Cohort. (May 2022). iScience.