A baby's smile not only lights up a mother's life -- it is also the right tonic that gives her a natural high, a new study has revealed.
Researchers have carried out the study and found that the sight of a smiling infant stimulates the 'feel-good' part of the mother's brain which deals with sensations of reward and pleasure too.
"These are the areas that have been activated in other experiments associated with the neurotransmitter dopamine. It may be that seeing your baby's smiling face is like a natural high," lead researcher Lane Strathearn said.
Dopamine is a key chemical messenger in the body, important for motivating, sleeping and controlling movement.
For the study, the researchers put 28 first-time moms of babies, aged between five and ten months, into a magnetic resonance imaging (MRI) brain scanner, British newspaper 'The Daily Telegraph' reported.
The participants were then asked to look at pictures of their own and other babies. In some of the pictures, the children were seen smiling and in others they had sad or neutral expressions.
When the mothers looked at the faces, the machine showed the flow of blood in their brains and revealed the regions that were the most active at any time.
As mothers identified their own children, the areas of the brain associated with 'reward' were on alert and the brain chemical dopamine was seen to be active.
In fact, the strength of the reaction depended on the expression of the babies and smiling faces triggered the biggest reaction, while neutral or sad-looking babies provoked the least response.
Crying babies made little difference to the reward centres of the brain -- mothers reacted to their own crying babies in exactly the same way as a stranger's crying child, the study revealed.
According to the researchers at the Texas Children's Hospital, the findings could explain the strong bond between mothers and babies -- and possibly why that bond is sometimes missing.
"The relationship between mothers and infants is crucial for child development and in some cases, that doesn't develop normally. Neglect and abuse can result in devastating effects on a child's development," Dr Strathearn said.
The study has been published in the latest edition of the 'Pediatrics' journal.