Babies can 'contract' depression from their mothers while they are still in the womb, new research suggests.
This increases their risk of developing the condition later in life.
A combination of genetic and environmental factors can mean children with depressed mothers are at an increased risk of both anxiety and mood disorders.
Scientists found changes in a part of the children's brains called the amygdala - this is responsible for controlling emotion and stress.
Previous research into the effects of maternal depression on children has assessed children years after birth meaning the timing of these changes in their brains has never been looked at.
Researchers at the National University of Singapore wanted to examine prenatal depression and the way it changes babies' brains.
They asked 157 pregnant women to answer a questionnaire during the 26th week of pregnancy.
Within two weeks of birth their babies were given MRI (magnetic resonance imaging) scans to look at the structure of their brains - in particular the amygdala.
The mother's level of depression had no effect on its volume.
However, researchers found reduced 'structural connectivity', or abnormal wiring, in the right amygdala of the infants with more depressed mothers.
The finding suggests that abnormal amygdala function, linked to mood and anxiety disorders, can be transmitted from mothers to babies before birth.
Researchers believe that a history of maternal depression might contribute to a lifelong increased risk of mental illness in children.
The study also adds weight to the theory that pregnant women should be given mental health screening and that "interventions targeting maternal depression should begin early in pregnancy".
Dr John Krystal, from the University of Yale School of Medicine and the Editor of Biological Psychiatry, said: "Attention to maternal health during pregnancy is an extremely high priority for society for many reasons.
"The notion that maternal depression might influence the brain development of their babies is very concerning.
"The good news is that this risk might be reduced by systematic screening of pregnant women for depression and initiating effective treatment."
The study is published in the current issue of Biological Psychiatry.
- DAILY MAIL