Newborn babies’ eyes often change color after birth. Many infants are born with blue or gray eyes, but this initial hue is frequently not their permanent eye color. This is a normal part of infant development, influenced by biological processes as a baby adjusts to the world. The final eye color can settle into various shades, including blue, green, hazel, or brown.
Melanin and Eye Color
The primary determinant of eye color is a pigment called melanin, which is also responsible for skin and hair color. Melanin is produced by specialized cells called melanocytes, located in the iris, the colored part of the eye. The amount and type of melanin present in the iris dictate its color. For example, brown eyes have a high concentration of melanin, while blue eyes have very little. Green and hazel eyes contain intermediate amounts.
Babies are born with lighter eye colors because their melanocytes are not yet fully activated by light exposure. Inside the dark environment of the womb, there is minimal light to trigger significant melanin production. After birth, as a baby’s eyes are exposed to light, melanocytes begin to produce and secrete more melanin. This increase in pigment can cause the eyes to darken over time. The way light scatters off the iris, particularly in eyes with low melanin, also contributes to the appearance of blue eyes.
The Timeline of Change
Changes in a baby’s eye color begin in the first few months of life. Most noticeable shifts occur between three and nine months of age. During this period, the production of melanin increases, leading to the gradual darkening of the iris. While the rate of change slows after six months, the final eye color may not fully stabilize until a child is around one year old.
Subtle changes can continue for several years, up to three years of age. In rare cases, eye color can continue to shift into adolescence or adulthood. Changes progress from lighter to darker shades; for example, blue eyes may turn green or brown, but brown eyes are unlikely to become blue.
Predicting Your Baby’s Final Eye Color
A baby’s permanent eye color is determined by genetics. Eye color is a polygenic trait, meaning it is influenced by multiple genes, not just one. While a single gene was once thought to control eye color, scientists now understand that up to 16 different genes play a role. This complex interplay of genes means that predicting a baby’s exact eye color with certainty is not possible.
Parental eye color can offer clues, but it does not provide a guarantee. For instance, two blue-eyed parents are likely to have a blue-eyed child, but it is not a 100% certainty. Similarly, two brown-eyed parents have a high probability of a brown-eyed child. If one parent has brown eyes and the other has blue, the chances of the baby having either brown or blue eyes are roughly even. The presence of certain genes, like OCA2 and HERC2, which regulate melanin production and distribution, are significant factors in the final hue.