Mothers who suffer from 'baby blues' while pregnant are four times as likely to have children who become violent teenagers, a new study shows.
The link remained even if the mothers did not suffer depression after their children were born.
Research has previously suggested that postnatal depression can affect a child’s subsequent behaviour.
But experts from Cardiff and Bristol universities and King's College London believe that theirs is one of the first studies to look at the effects of suffering depression before a child’s birth.
Many women are depressed during their pregnancy and research by Tommy's, the baby charity, suggests that it may even be more common before the birth of a child than after.
It is estimated that as many as between 10 and 15pc of women could suffer the condition while they are expecting.
Prof Dale F Hay, from Cardiff University, who led the latest study, said: "Much attention has been given to the effects of postnatal depression on young infants, but depression during pregnancy may also affect the unborn child."
The study looked at 120 mothers from the Bristol area.
The researchers interviewed the women while they were pregnant, after they gave birth and when their children were aged four, 11, and 16 years old.
Their findings, published in the journal Child Development, show that women who were depressed while they were pregnant were four times as likely to have children who were violent by the age of 16 as the other mothers.
The children were also more likely to exhibit other forms of anti-social behaviour, the research found.
However, the study also found that women who had been angry or disruptive teenagers themselves were more likely to go on to be depressed while they were pregnant.
Prof Hay added: "Although it's not yet clear exactly how depression in pregnancy might set infants on a pathway toward increased anti-social behaviour, our findings suggest that women with a history of conduct problems who become depressed in pregnancy may be in special need of support."