The Eyes Have It: Determining Baby's Eye Color

By:  Michelle Place, CRNP-P
Who will baby look like? It is anyone’s guess. Expecting a baby is such an exciting time! Should you paint the nursery blue or pink? Will the baby have the same cleft in his chin as daddy or mommy’s dimples or grandma’s blue eyes?
Eye Color
Eye color refers to the hue of the iris. The iris is the muscle that controls the amount of light that enters the eye by dilating or constricting the black pupil in the center. There are cells in our skin, hair and eyes called melanocytes which produce the protein that is responsible for pigmentation. This protein is called melanin. The more melanin produced, the darker things will become.
In the eyes, a lot of of melanin results in brown peepers looking back at you.
A little less gives you green or hazel.
If you produce almost no melanin you end up batting baby blues.
Albinos have no melanin at all, their eyes look pink or red because the lack of pigment allows the blood vessels in the back of the eye to show through.
Here Comes the Sun
In order for melanocytes to work they need exposure to ultraviolet rays. This explains why our skin gets darker after basking in the sun. Most newborns have dark blue or slate gray eyes because until they are born they have spent all their time in a warm, dark place. Once they emerge into the light the melanin starts flowing.
Mom + Dad + Baby
Genetics determines how much melanin your baby will produce. The genetics of eye color is much more complicated than those punnett squares from high school biology class would lead us to believe. Two brown eyed parents will most likely have a brown eyed baby (brown eyes is the color that occurs most often) but throw in a blue-eyed grandparent and anything goes. Two blue-eyed parents will probably have blue-eyed offspring but it is not 100% guaranteed. One brown eyed parent and one blue eyed parent could result in any color on the spectrum. In our family blue-eyed mom plus hazel-eyed dad ended up with one pair of green eyes, 2 blue-eyed babies and this set that are hazel.
How long must we wait?
So, when will you know for sure what color your baby’s eyes will be? Well, if parenting teaches us anything it is that patience is a virtue. Unless you cheated and found out your baby’s gender via ultrasound (like I did) you had to wait 9 months to discover whether you were having a boy or a girl. You may have to wait at least another 9 months for eye color to be fully determined. A general rule of thumb is that if eyes look dark they probably will not go lighter. The melanocytes get the majority of their work done in the first 6-12 months so you should have a pretty good idea about what you are going to get by your baby’s first birthday. Some subtle changes may continue until the age of 3, eyes that appear blue at 12 months may end up green or grey given a little more time.