Babies can smile in the womb, even before they are born. A baby’s earliest smiles are reflex smiles, not an attempt to imitate or engage with adults.

As babies grow, they develop more social skills and control over their movements. According to some experts, most babies begin regularly smiling between 6 and 12 weeks of age. Some may smile in response to a loved one’s smile a little earlier.

This article looks at why and when babies start to smile.

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Babies have the ability to smile from birth, but it often takes 6–12 weeks for real smiles to develop.

Babies can smile from the moment they are born.

However, a real smile takes time to develop. A real smile is one the baby gives in response to a parent or caregiver or reflects the baby’s content state.

When a baby is between 6–12 weeks, parents and caregivers should see more consistent smiles.

The Centers for Disease Control and Prevention (CDC) say that most babies give a real, non-reflexive smile when they are about 2 months old.

Babies smile for many reasons, including:

  • Reflex smile: This is the smile babies develop in the womb. However, babies do it randomly, not in response to happiness or a caregiver. Therefore, experts do not consider it a real smile.
  • Social smile: This is a smile in response to contact with others, such as smiling back at a caregiver or smiling to get the caregiver’s attention.

As babies grow and develop, they may also smile when they are happy, whether or not they are interacting with a caregiver.

For example, a caregiver might see an older baby smile while playing with a favorite toy.

Some guides suggest talking to a doctor if a baby does not communicate with a smile or other expressions by 3 months.

All babies develop on slightly different schedules. Individual differences, such as family interactions, cultural norms, and being born prematurely, may affect development.

Premature babies tend to reach developmental milestones later than babies born at term, so doctors often assign them a corrected age.

The corrected age reflects the age that the baby would be if they had not been born prematurely. It is normal for a baby born one month early to behave more like peers who are a month younger, and they may smile about a month later than average for babies of their age.

If a baby does not smile, parents should prioritize face-to-face interactions. Focus on smiling, playing, singing, and doing other activities the baby enjoys.

If the baby still does not begin smiling, it could signal a range of issues, including:

  • Vision problems: Blind or low-vision babies may not see their parents’ smiles or respond to them.
  • Hearing issues: Children with hearing impairments may not smile at the sound of coos, giggles, or a parent’s voice.
  • Autism: Autistic babies may not smile at caregivers or may have other differences in social skills.
  • Temperament: Some babies are shyer, less interactive, or smile less readily than others. If a baby can and does smile but smiles less than some other infants, it might just be the baby’s personality.

Reflex smiles simply mean that the muscles in the baby’s face work normally.

In the early weeks of life, babies try out a wide range of expressions. As they develop relationships with caregivers and deeper social connections, they begin to smile when they are happy or to imitate a caregiver’s smile.

Children who do not smile or who do not smile at caregivers may have a developmental issue.

Smiling can also be a reflection of culture and the environment. A 2012 study looked at smiling in infants between 6 and 12 weeks of age.

The study compared infants from families with many face-to-face interactions to those whose families had fewer face-to-face interactions.

Mothers and babies from both groups smiled at one another for similar lengths of time when the babies were 6 weeks old. By 12 weeks, babies and mothers from the community with fewer face-to-face interactions smiled and imitated one another’s smile less.

This suggests that babies take smiling cues from their family and culture and that babies who experience more frequent face-to-face interactions may smile more.

Parents should discuss their baby’s developmental milestones at each routine healthcare visit, especially if a baby has not hit age-typical milestones.

If a baby does not begin imitating caregivers’ smiles between 6 and 12 weeks of age, talk to a doctor.

Other reasons to talk to a doctor include if a baby:

  • stops smiling at caregivers
  • seems very uncomfortable with eye contact or never smiles when looking at caregivers
  • loses any recently acquired skills, including smiling
  • does not smile by 3 months

A baby’s first “real” smile is an important milestone that may help parents and caregivers feel more connected to their baby.

It can take time for a baby to get into the habit of smiling regularly. When babies do not smile, early interventions can ease the challenges of developmental and other issues.

If a parent or caregiver is concerned their baby may not be smiling normally, they should talk to a pediatrician.