When Do Babies Start Smiling? We Asked a Pediatrician

When do babies start smiling? While some flash a smile in utero, the typical newborn cracks a grin in relation to an emotional trigger (called a “social smile”) around two months. Still, according to Dr. Dyan Hes, the medical director of Gramercy Pediatrics in New York City, it could happen as early as six weeks.

But what are the reasons for a smile? And what can you do to encourage them? We checked in with Dr. Hes for the hows, whats and whys of bringing on a happy face. Here’s what we learned.

A disclaimer from Dr. Hes before we dive in: No milestone is set in stone. “Most babies smile around the time they turn two months old,” she says. “But some babies may have a social smile at six weeks and some may develop it closer to three months.” In other words, if your little one doesn’t flash a smile exactly at the two-month mark, don’t fret. Everything varies, depending on the baby.

How to tell the difference between a smile that’s social versus one that’s more of a reflex (the case with gas)? A social smile is typically in direct response to something. Say, a humor-infused board book reading. Or an over-the-top diaper change. If your newborn smiles in connection to that—external stimuli—it’s genuine. (Even the sight of their mama can spark a grin.) You’ll also know because you’ll see their eyes light up. Even with newborns, there’s an emotional connection that’s very much visible when they flash a real smile.

On the other hand, if a smile is short and random—or occurs while they’re sleeping—it’s more likely to simply be a reflex. “Prior to two months of age, some babies have grimaces or primitive smiles. This may also be passing of gas,” Dr. Hes explains. “There is usually no social intent with these smiles and they cannot be elicited again on demand.” (A social smile can typically be repeated in the moment when you recreate the same stimuli.)

According to Dr. Hes, this particular achievement is actually their way of communicating. “Babies enjoy looking at your face closely and they are trying to interpret your expressions,” she says. “When a baby smiles, she is responding to the stimulus around her and she also realizes that she gets a happy emotion from the adult when she does it, so learns to do it again.”

It’s a cause-and-effect thing. Your baby recognizes that a smile is a way to interact with others. Dr. Hes adds: “It’s their way of communicating without having to cry.”

The best thing you can do to encourage children to smile is talk to them. A reminder from Dr. Hes: Babies can see best 10 to 12 inches from their face during this time, so it’s ideal if whatever you’re doing to make your little one smile happens relatively close up.

Also, as mom and dad, you’re in the most prime position when it comes to getting a grin. “Babies tend to smile for their parents well before strangers with whom they are just not comfortable yet,” says Dr. Hes. (Eventually, they’ll be exchanging grins with strangers, too—although that will temporarily come to an end when they hit the stranger-danger phase around six months.)

Another tactic is to use exaggerated expressions yourself. In other words, go all in on that over-dramatized book reading or song-singing. And it doesn’t hurt to show off your own ear-to-ear grin when something delights you.

You can also get physical with your newborn. Think: blowing raspberry kisses on her belly or bouncing her up and down. Playing peekaboo is another tried-and-true method for seeing a smile. Or mimic animal noises while holding her lovey or favorite stuffed toy. The sillier, the better, of course.

By the the time she hits four and a half to five months, her smile will probably come with major belly laughs, too.

If you pass the three-month mark and your baby still hasn’t smiled, it’s worth getting in touch with your pediatrician to let them know, says Dr. Hes. But, again, if it doesn’t happen by the two-month mark, give your child some wiggle room. After all, these timelines are really just approximations.