When do baby's laugh?Infants between 0 and 5 weeks of age may show spontaneous laughter, between 5 weeks and 3.5 months of age they may show indiscriminate social smiles, and after 3.5 months they may show selective social smiles.

Spontaneous laughter

generally starts when the baby is born, but the initial laughter is spontaneous and a physiological manifestation, not a social smile. This early laughter gradually decreases after 3 months.

Unselective social smile

appears when the baby is 5 weeks to 3.5 months old. At this stage, human voices and faces are likely to cause the baby to smile.

Selective social smile

At the age of 3.5 months, and especially from the age of 4 months, as the baby grows and develops and its ability to process the content of stimuli increases, the baby can distinguish between familiar faces and other strangers, and begins to smile differently at different people, showing a selective social smile.

If it is found that the baby does not smile until the age of 4 months or older, it means that overall development is deviant from the normal range, and it is recommended to go to the children's hospital for a timely consultation.