It’s hard not to feel overjoyed when your baby gazes adoringly into your eyes and flashes a brief, but unmistakable smile. But is she really trying to communicate her joy at seeing you, or does she simply have gas?

Babies usually don’t start social smiling until about eight months, but their smiles can still say a lot before then. “In fact, babies smile when they’re asleep from birth,” says Dr. Daniel Messinger.

Baby smiles at 0-1 months

Neonatal smiling occurs from birth to one month of age and shows no emotional content. Smiles are spontaneous and often occur while the baby is drowsy or during REM stages of sleep. Baby smiles are subcortical in origin and will actually decrease with maturity (so premature babies smile more than full-term babies). And, contrary to popular belief, baby smiles have nothing to do with gas.

Baby smiles at 1-2 months

At around one or two months, babies will gradually start to respond to environmental stimulation. Your baby’s first smile when she’s fully awake will likely appear between six and 10 weeks.

At this age, your baby’s brain is developing, her vision is improving and she can recognize your face. Your baby will likely respond to auditory stimuli first, such as music or mom or dad’s voice. Next comes a response to visual and auditory stimulation combined. The last thing to make baby smile is visual stimulation alone.

Baby smiles at 2-6 months

“Earlier is not better,” says Dr. Messinger. But you should see a doctor if your baby is not smiling by three months. Don’t push your little one to smile, but once she does, have fun with it. At two to three months, you’ll notice your baby starts to look right at you when she smiles. During this time period babies will increasingly respond to face-to-face interaction. Make funny faces to get your baby to laugh.

By four to six months, your baby will start to smile, then look away. “Babies are learning to regulate emotions and the joy may be too intense,” says Dr. Messinger. Let her look away, then reengage once she returns her smile to you.

Baby Smiles at 6-12 months

During this period you will start to see lots of different smiles. As a general rule, open mouth smiles demonstrate more joy than closed. Your baby will also start to play with laughter. By eight or nine months, smiles are used often in social situations and as a method of communication so make sure to respond to your baby when she gives you a big smile.

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