When Does a Baby's Eye Color Change?

8 sources cited
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What Color are Babies’ Eyes When They’re Born?

Most babies (63%) are born with brown eyes, but color variations exist. Studies show newborns of Black, Indigenous, and People of Color (BIPOC) are likely to have brown eyes at birth.1 The brown shade may darken slightly with time. 

On the other hand, most Caucasian babies are born with blue or gray eyes that may change to green, hazel, amber, or brown depending on the amount of melanin present in the iris (the colored part of the eye). 

For reference, melanin is a substance produced by cells known as melanocytes. It’s responsible for skin, hair, and eye color.2 Melanin also protects the photoreceptor cells in the retina against infrared, visible light, and absorbed UV radiation.3 

The type of melanin responsible for brown eye color is eumelanin (black or brown). Pheomelanin (reddish-yellow) combines with the light-scattering effect of the iris (which makes eyes look blue) to make eyes appear green. Green eyes are the least common, accounting for only 9% of the US population.

Babies often have less melanin in their irises at birth. This changes as their eyes respond to light.

When Does Eye Color Change in Babies?

Just like skin color, a baby's eyes change color due to exposure to sunlight. You’ll notice significant changes before their first birthday. The most noticeable ones will occur around 3 to 6 months after birth

At this point, you can most likely predict the baby’s final eye color. However, wait a few more months for a more stable eye color.

According to eye experts, most babies will have their lifetime eye color by the time they’re 9 months old.4 However, some may take up to 3 years to have a permanent eye color.

What Determines Eye Color?

Every baby has the same type of melanin in their eyes. The variations in eye color are determined by the amount and quality of this pigment. Scientists have also defined eye color as an inherited trait.

Melanin Production

Eye color is determined by the amount and quality of melanin pigment in the front layer of the iris (stroma).5 Babies are often born with less melanin in the eyes due to the darker conditions in the womb. After birth, exposure to sunlight activates the melanocytes to produce more melanin. 

Melanin production over time will vary from child to child, affecting the final eye color. When light hits the irises of eyes with less melanin, it splits into various colors (Rayleigh scattering), causing hazel, gray, amber, green, red, or blue eyes. On the other hand, large amounts of melanin will result in a darker shade (dark brown).

Just like fingerprints, the amount of melanin produced is unique to every child. 

Genetics 

A baby’s family history will determine the amount of melanin they produce. Two brown-eyed parents will most likely have a brown-eyed baby. However, this is not guaranteed since one, or both, parents may have a recessive gene for blue eyes. 

On the other hand, blue-eyed parents will most likely give birth to a blue-eyed baby. If only one parent has the blue eye gene, there’s a chance of a blue or brown-eyed baby. 

A special gene, known as OCA2 or P gene, is responsible for activating melanocytes to produce melanin.6  The amount and quality of melanin produced is determined by a protein known as P protein. Less P protein means less melanin in the iris, hence lighter-colored eyes.

Another special gene that contributes to eye color is HERC2. It regulates the action of OCA2 by turning melanin production off or on. Other minor genes that contribute to eye color include:

  • ASIP (Agouti Signaling Protein)
  • IRF4 (Interferon Regulatory Factor 4)
  • SLC24A4 gene
  • SLC24A5 gene
  •  SLC45A2
  • TPCN2 (Two Pore Segment Channel 2)
  • TYR gene
  • TYRP1 gene

Ethnicity/Region

Children born to Black, Asian and Hispanic parents have dominantly brown eye genes.7 In Europe, the colors may vary by region. 

For example, eye color tends to be lighter in Northern Europe and darker in the South. Experts attribute this to climate variations, something which affects the level of exposure to sunlight.8

Health Conditions

Below are common conditions that affect the production of melanin in the eyes.

  • Ocular albinism. It affects the pigmentation of the iris, resulting in very light eyes and vision issues.
  • Oculocutaneous albinism. It affects melanin production, resulting in fair or light-colored eyes, hair, and skin.
  • Heterochromia. It’s characterized by differently colored eyes and is caused by genetic changes, problems with eye development, injury, or disease.

Summary

A baby’s eye color at birth depends on melanin production in the iris. Most babies are born with brown eyes, but color variations exist and may change with time.

According to studies, newborns of Black, Indigenous, and People of Color (BIPOC) are likely to have brown eyes at birth, while Caucasian newborns are likely to have dark blue or gray eyes. 

Just like skin color, eye color in babies changes after 3 to 6 months of exposure to light. Babies born with blue eyes may end up with amber, red, brown, green, or hazel eyes.

Factors that determine a baby’s eye color include the extent of melanin production, family history, ethnicity, and the presence of eye conditions such as albinism or heterochromia (differently colored eyes).

8 Cited Research Articles
  1. Ludwig C. et al., “What color are newborns' eyes? Prevalence of iris color in the Newborn Eye Screening Test (NEST) study,”  Acta Ophthalmologica, 07 Apr. 2016
  2. Melanin,” Cleveland Clinic, 29 Mar. 2022. 
  3. Istrate M., Vlaicu B., et al.,Photoprotection role of melanin in the human retinal pigment epithelium. Imaging techniques for retinal melanin,” Romanian journal of ophthalmology, 64:100-104, 20 Apr. 2020
  4. Rauch K., “Why Are My Eyes Changing Color?,”  American Academy of Ophthalmology (AAO), 07 Jan. 2021
  5. Is eye color determined by genetics?,” National Library of Medicine
  6. OCA2 gene: OCA2 melanosomal transmembrane protein,” National Library of Medicine, 13 May, 2022.
  7. Mukamal R.,“Why Are Brown Eyes Most Common?,” American Academy of Ophthalmology (AAO), 07 Apr. 2017
  8. Why almost people in Europe have blue eyes and blonde hair?,” University of California, Santa Barbara, 2007.
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