Many parents observe that their newborn babies often have blue eyes, leading to questions about whether this is always the case and what causes this common phenomenon. This article explores the science behind why many babies are born with blue eyes and how their eye color can change over time.
Why Many Newborns Have Blue Eyes
Many newborns have blue eyes due to undeveloped melanin production. Melanin is the pigment that determines the color of our eyes, skin, and hair. At birth, melanocytes in a baby’s iris have not yet begun to produce or deposit significant amounts of this pigment.
Without much melanin in the iris, the blue appearance results from the scattering of light. The collagen fibers within the iris scatter shorter, blue wavelengths of light more effectively. Similar to how the sky appears blue, this allows only blue light to reflect, making the eyes appear blue. This initial blue hue is often a temporary state, reflecting the pigment system’s immaturity.
The Genetics of Eye Color
A baby’s potential eye color is determined by genetic information inherited from both parents. Eye color is not controlled by a single gene but rather by the complex interplay of multiple genes. These genes influence the specific type and amount of melanin an individual will produce in their irises.
Different combinations of these genes dictate the level of melanin production, leading to a wide spectrum of eye colors. For instance, high levels of melanin result in brown eyes, while moderate levels can produce green or hazel eyes. If a baby inherits genes that program for very little melanin production, their eyes are more likely to remain blue. The genetic blueprint sets the stage for the final eye color.
When and Why Eye Color Can Change
While genetics provides the potential for eye color, the actual production and distribution of melanin in the iris develop over a baby’s first few months. As a baby is exposed to light outside the womb, the melanocytes in their irises are stimulated to increase melanin production. This gradual increase in pigment often causes a baby’s eye color to shift.
The typical timeline for eye color stabilization varies among individuals, but it often occurs between six to twelve months of age. However, some babies may experience subtle changes in eye color up until they are three years old. If a baby’s eyes accumulate more melanin, their color can transition from blue to green, hazel, or brown. Conversely, if a baby’s eyes remain blue, it indicates that their melanocytes produce very little melanin, and the light scattering effect continues to dominate.