06/11/2018 13:15 GMT | Updated 06/11/2018 13:21 GMT

When Do Babies' Eyes Change Colour? Giovanna Fletcher Muses Whether Her Son's Will Go Brown

Her older son's eyes changed from green to brown 👀

Have you noticed your baby’s eyes change colour in their first few months of life? This is something Giovanna Fletcher has been pondering with her three-month-old son Max, who currently dons a pair of baby blues. 

The mum-of-three, married to musician Tom Fletcher, asked fellow parents if this has happened to their kids, given that her now four-year-old son Buzz’s eyes did change colour when he was a baby.

“Me and Tom both have brown eyes,” the 33-year-old wrote on Instagram. “Buzz’s were emerald green until they changed to a bright brown at five months, Buddy’s were super dark brown from the moment he was born. Max has blue eyes. I imagine they’ll turn brown at some point, but who knows?!”

The colour-changing phenomenon happens to some babies, not all, and is dependent on the amount of melanin in the iris. Melanin is the pigment responsible for giving human skin, hair and eyes their colour.

Light is responsible for the change, according to Heidi Murkoff, author of the popular ‘What to Expect When You’re Expecting’ guides. This is because exposure to light initiates melanin production in the iris which can then change a baby’s eye colour.

Babies born with light-coloured eyes, such as blue or light grey, have less melanin in their iris so there’s potential for their eyes to change colour over time, as more melanin is produced.

The biggest change tends to happen between the ages of six and nine months old – although it’s not uncommon for eyes to change subtly up until the age of three. Some even continue changing into adulthood, but this is rare.

It’s worth noting that the colour change only tends to happen in white people who are fair-skinned. Babies with dark-coloured eyes will not usually experience a change in eye colour. 

So if your little one is a blue-eyed baby now, be prepared that it could well change.