Dr. Jacobson says babies should start smiling between four weeks and two months so don't be fooled by earlier "grins."
At first you may notice smiles while they sleep, which is referred to as a "reflexive smile." The main difference is that it's not triggered by a social stimulation, according to the American Psychological Association. Or perhaps you've seen a "gas smile," which happens when they're passing wind.
It can be hard to tell the difference between social smiles and these other types, but one clue: typically, other smiles are characterized by an upturn of the lips. When they give you a social smile, they'll smile with their whole face.
A genuine or "social smile" represents friendliness and pleasure. It's a milestone because it shows the baby is smiling as a form of communication. Aw!
