Mothers who cradle their baby on the right side of their body could be showing signs of extreme stress.
The way women hold their babies may reflect their mental state
According to researchers at Durham University, the way mothers hold their baby can show whether they are feeling overwhelmed or becoming depressed.
And psychologist Dr Nadja Reissland insisted it did not matter whether women were right or left-handed.
It is believed the study results could be used to decide whether new mothers need extra help and support.
At least one in 10 women suffers from post-natal depression, yet many go undiagnosed as they are unwilling to ask for help, according to researchers.
The study, published in the online version of the Journal Of Child Psychology And Psychiatry, involved 79 new mothers and their babies, who were an average age of seven months.
The mothers were interviewed at home and asked to pick up their baby in their arms.
They then completed a survey about their feelings and mental well-being.
The study, backed by the Children's Research Fund, found that of the mothers who expressed no signs of stress or depression in the survey, 86% preferred to hold their babies to the left.
Dr Reissland said: "Many mothers don't realise they are suffering from stress, or don't want to admit they are.
"The way they interact with their child is usually the best indicator of their inner mental state.
"Mums who are stressed often see what their baby does as negative so they may interpret their baby's crying as being naughty, when in fact it is normal behaviour.
"If this stress develops into depression, then the situation can be even worse."