A baby smiles intentionally for the first time between six and eight weeks, sometimes as late as twelve weeks for a baby born prematurely. Before that, the smiles observed from birth are reflex smiles, with no intention of communicating. The distinction between the two is easy to make once you know what to look for.
The reflex smile during the first few weeks
From the first few days, and even in the womb, newborns stretch the corners of their lips. This movement occurs mainly during REM sleep, while drowsy, or after a feeding. It is not directed at anyone.
This smile is brief, asymmetrical, and does not involve the eyes. It appears without any external trigger and disappears just as quickly. Parents often interpret it as a response; in reality, it is a motor discharge linked to the maturation of the brainstem.
That does not make it insignificant. These movements exercise the facial muscles and prepare the circuits that will be used for voluntary smiling. The reflex precedes the function, as with automatic walking or sucking.
The social smile: what changes around six to eight weeks
The social smile is directed at someone. It appears in response to a human face, a familiar voice, or sustained eye contact. It is the baby's first genuine act of communication.
Three signs distinguish it from a reflex smile. It engages the entire face, including the area around the eyes, which crinkles. It occurs during a period of calm wakefulness, in the presence of someone. And it is repeated when the interaction is encouraged.
This stage coincides with a decisive visual milestone. Around two months, babies can steadily focus on a face positioned thirty centimeters away and begin to distinguish its internal contrasts. We explain this timeline in detail in our article on baby vision from 0 to 12 months.
At what age do babies smile: milestones step by step
From birth to six weeks
Reflex smiles, brief and often occurring during sleep. No communicative value. The baby already focuses on faces but does not yet respond.
From six to twelve weeks
The social smile appears. The baby responds to a face leaning over them, provided they are calmly awake, neither hungry nor tired. Interactions remain brief, lasting only a few seconds.
From three to four months
Vocalizations accompany the smile. The baby initiates the interaction instead of merely responding to it. The first bursts of laughter appear, often during physical contact or surprise games.
From five to eight months
The smile becomes selective. The baby smiles more readily at familiar faces and shows reserve around strangers. This reserve, which peaks around eight months, is a sign of healthy development.
After nine months
The smile becomes part of more complex interactions. The baby looks back and forth between an adult and an object, then smiles. This joint attention prepares the way for language, as explained in our article on language development.
Why isn't my baby smiling yet?
In the vast majority of cases, it is because the baby is too young, tired, or being engaged at the wrong time. The social smile requires a state of calm wakefulness, which accounts for only a small part of an infant's day.
For a baby born prematurely, the milestone is calculated using corrected age rather than actual age. A baby born at thirty-two weeks will smile socially around two months corrected age, or approximately four months after birth. Our article explains how to calculate corrected age.
Temperament also plays a role. Some babies smile little but maintain eye contact for a long time, vocalize, and calm down through contact. It is these three signals together that matter, not the smile alone.
How to encourage interaction without forcing it
The most effective approach is face-to-face interaction. Position your face about thirty centimeters away, in the baby's line of sight, and leave a moment of silence after speaking. This silence gives the baby a chance to respond.
Many parents continue one stimulation after another without leaving any space. The baby becomes overwhelmed and turns their head away. This turning away is not a refusal but a way of regulating stimulation: the baby needs a pause to process the information received.
Floor time is among the most favorable opportunities. Lying on their back or tummy on a firm play mat, the baby does not have to fight gravity to hold their head up. They can then devote their available energy to visual interaction.
Our suggestions for activities suited to this period can be found in the article play mats for 0–6 months. They rely on minimal equipment and plenty of time and attention.
What a smile says about development
The social smile is a simultaneous marker of several functions. It requires sufficient vision to perceive a face, hearing that connects a voice with a person, and emotional regulation stable enough to remain calmly awake.
It also requires an emerging recognition memory. A baby who smiles more at their parents than at a new face has memorized certain features. This recognition process continues for a long time, through to self-recognition in the mirror around eighteen months.
Finally, smiling supports imitation. A baby who sees an adult smile tends to reproduce the expression, which in turn strengthens the interaction. This mechanism is described in our article on imitation in babies.
When to speak to a professional
Medical advice is warranted if no directed smile appears by three months corrected age. It is also warranted if an established smile disappears for an extended period, or if the baby never seeks eye contact.
These situations do not necessarily mean that a disorder is present. They do justify an examination, since early identification significantly improves support. The official French milestones are outlined in our article on identifying neurodevelopmental disorders.
The primary care doctor, pediatrician, and maternal and child health services are the first points of contact. Routine mandatory checkups also include an assessment of these interactions, without parents having to request it.
