It happens in my studio constantly. A baby a few days old smiles, both parents light up, and then somebody explains that it does not count.
I have photographed a great many newborns, and I have never quite believed it. So I went and read what the researchers say.
The short answer
The old textbook position was that a smile before about six weeks is a reflex — wind, a muscle twitch, nothing to do with anybody in the room. The first social smile was said to arrive in the second month.
That position has been eroding for years, and the evidence now points the other way. Newborn smiles look far more like real smiles than anyone used to think.
What changed
Three findings are worth knowing about.
The muscles. A genuine smile — a Duchenne smile — is not only the mouth. It involves the muscles around the eyes. Newborn smiles were assumed to be mouth-only. When researchers analysed video frame by frame with a proper coding system, they found that smiles from as early as the first day often do involve the cheeks and the eyes.
When they happen. Babies smile roughly twice as often when they are awake and interacting as when they are asleep. A pure reflex would not care whether anyone was there.
What comes first. Babies often move their cheeks and brows before they smile — as though gathering their attention onto the face in front of them.
Charles Darwin, who recorded his own child carefully, put the first real smile at forty-five days. Modern parent-reported data lands in a similar place, just after four weeks on average. But that is the age of the reliable, repeatable social smile. It is not the same as saying nothing before it is real.
What I see
I am a photographer, not a scientist, so take this for what it is: several hundred newborns, watched closely through a lens.
Very young babies do smile while they sleep, and those smiles are fleeting and unrelated to anything happening in the room. They are lovely, and they are probably not for us.
But I also see the other kind. A baby who has been settled, is awake, is looking towards a parent's voice — and smiles. It lasts longer. It arrives at the moment the parent speaks. I have caught it often enough to have stopped calling it coincidence.
At six weeks it stops being a matter of opinion: the smiles become unmistakable, they answer a face, and they can be invited. I have written about what that changes in photographing babies at six weeks.
Why it matters for a photograph
Because parents are right to want it kept.
A newborn photograph of a sleeping baby is beautiful and it is what most people book. But a photograph of a very small baby who is awake and smiling towards the person holding them is a different kind of picture — and if you have been told all week that it was only wind, having it on the wall is a quiet argument to the contrary.
I do not chase smiles in a newborn session; a baby that young cannot be asked. But I stay ready for them, and when one arrives I would rather have it than the pose I was setting up.
The research summarised here is set out by Emese Nagy, Reader in Psychology at the University of Dundee, in Newborn smiles aren't just a reflex for The Conversation. It is worth reading in full.
If you would like these first days photographed, here is what a newborn session involves and what it costs.