When Do Babies Smile

The two kinds of smile

Newborns smile from the first days of life. These early smiles happen mostly during sleep or as fleeting expressions while drowsy, and they are not directed at anyone. They are sometimes called reflex smiles.

The smile parents are waiting for is the social smile: a smile given in response to your face or your voice, which arrives later and is unmistakable when it does. The difference is not how it looks but what triggers it. A reflex smile happens to a sleeping baby. A social smile happens because you leaned over the cot.

The folklore explanation — that early smiles are wind — is not supported by any published source, and no health body describes newborn smiling as a digestive event. It is simply a face doing what faces do before the social wiring arrives.

When the social smile is expected

The clearest published marker comes from NICE. Its postnatal care guideline NG194 instructs that "at 6 to 8 weeks, assess the baby's social smiling and visual fixing and following". That is a formal part of the review your baby is offered at that age, and it tells you the age by which a social smile is expected to be present.

The HSE's eyesight development timeline gives the same window from a different angle: by six to eight weeks your child may look at you, follow your face and smile back when you smile, follow a coloured toy about 20cm away, and move both eyes together.

The AAP's one-month milestones sit just before this: at a month old, babies are expected to calm when picked up or spoken to, look at your face, and seem happy to see you when you walk up. The smile that follows is the next step in the same sequence.

The HSE's developmental milestone lists for the following months add: smiling more often, especially at parents or main caregivers; giving warm smiles and laughing in response to your smiling, chatting and singing; and later smiling at themselves in a mirror.

Why it arrives when it does

A social smile needs two things: the ability to see your face clearly enough to respond to it, and enough social wiring to want to.

The vision half is the easier one to explain. The AAP says a newborn sees best at about 20 to 30cm — roughly the distance from their eyes to yours during a feed — and that a newborn's eyes may wander or look crossed when you are further away. By around three months, babies should be able to focus on faces and close objects and follow a moving object. Faces come into focus at about the same time smiles start being aimed at them.

The AAP's account of newborn behaviour adds why faces win: babies naturally prefer the human face over other visual patterns, and the human voice over other sounds. A smiling, talking parent at close range is the most interesting thing in a newborn's world.

What actually helps

• Get close. Twenty to thirty centimetres. Anything further and you are outside their focus.
• Smile first, and wait. Newborn responses are slow; give several seconds before you conclude nothing is happening.
• Talk while you smile. Voice and face together are far more powerful than either alone, and the AAP notes babies particularly respond to raised pitch, slowed speech and exaggerated expressions.
• Catch them in quiet alert time. A newborn who is calm, awake and looking around is receptive. A drowsy, hungry or overstimulated one is not.
• Chat during nappy changes. The NHS suggests exactly this — pulling faces, smiling and laughing with your baby while you change them helps you bond and helps their development.
• Do not perform. Overstimulation makes newborns look away. Looking away is a signal to pause, not to try harder.

If your baby is not smiling yet

Two adjustments before you worry. If your baby was born prematurely, milestones are usually counted from their due date rather than their birth date, so a baby born two months early may reach a social smile around two months later than the calendar suggests. And there is normal variation between babies within any milestone window.

What makes this worth checking rather than waiting out is that a missing smile can be an early sign of a vision or hearing problem, and both are treatable when caught early. The HSE lists "not learning to respond to facial expressions — for example, not smiling" among the signs of an eye problem in younger children, alongside not fixing on and following an object after six to eight weeks, eyes that are not looking in the same direction, and sensitivity to light.

NICE's fever guideline also uses smiling as a clinical sign in the other direction: "content or smiles" sits in the low-risk green group of the traffic light system, and "no smile" is an intermediate-risk amber sign in a child who is unwell. A baby who was smiling and has stopped, in the context of illness, is a different and more urgent question from a baby who has not started yet.

When to call

Speak to your health visitor, public health nurse or GP if your baby:

• Is not smiling socially by around eight weeks, corrected for prematurity.
• Is not fixing on and following your face by six to eight weeks.
• Does not respond to your voice, or does not startle to loud sounds by around a month old.
• Has eyes that are not looking in the same direction, or is very sensitive to light.
• Was smiling and has stopped, or has become less responsive generally.
• Is not making eye contact, or seems not to notice you approaching.

The six to eight week review exists for exactly this, so if the appointment is coming up, write the concern down and raise it there. If it is not, you do not have to wait.

Call your local emergency number (999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, 111 in New Zealand) if your baby: is unresponsive or unrousable; has a temperature of 38C (100.4F) or above or below 36C (96.8F); looks pale, ashen, mottled or blue; has a weak, abnormally high-pitched or continuous cry; is grunting or breathing over 60 breaths a minute; has a bulging fontanelle, neck stiffness or a seizure; or has a rash that does not fade under a pressed glass. Those are NICE's red flags for serious illness in young babies, from NG194.

What to let go of

Whether the first one "counted" is not worth deciding. Wind is not the explanation, prematurity shifts the timetable, and the formal check happens at six to eight weeks whether or not it has happened at home. Get your face to about twenty-five centimetres, talk, and wait — it arrives, and then it does not stop.