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Dads who suffer from the Baby Blues could cause future behaviour problems in their children, researchers claim.
Some fathers suffer from postnatal depression so severely that they are unable to properly interact with their offspring.
Researchers at Oxford University found that depressed fathers spend less time talking and playing with their babies.
And they believe this lack of interaction in the first few months of a child's life could lead to behavioural problems.
The researchers looked at 38 new fathers, of whom half had post natal depression. Their babies were all three months old when the study was conducted.
The academics filmed how the fathers played and spoke to their babies over a period of three minutes.
On average, the men with depression spoke less to their babies and were more worried about themselves.
They seemed to be self-conscious and made comments such as: "Daddy hasn't lasted very long has he?" or "I can't think of anything to do all of a sudden."
The researchers, whose study is published in the journal Psychological Medicine, think that these communication problems early on may affect the development of the child as they grow up.
Previous research has suggested that children whose fathers had the condition were more likely to throw tantrums and be trouble-makers at school.
Dr Paul Ramchandani, from the Department of Psychiatry at Oxford University, said: "Although dads don't have all the same hormonal changes as mothers do, they do often experience dramatic changes to their life.
This can be a positive thing for many dads, but for some, the combination of sleep deprivation, additional pressures of responsibility of caring for a new baby, and sometimes then being the sole breadwinner, for a while at least, can bring additional stress.
"Any life event can increase the risk of depression. Other studies have shown that children whose dads have had depression are at increased risk of psychological difficulties, including behavioural problems.
"The reasons for this are not entirely clear, but one is likely to be that depression affects the way dads interact with their children, and this is what the present study is about.
"The key thing was that depressed dads spoke less to their children, were more focused on themselves, and tended to be more negative.'
It is estimated that between 4 and 5 per cent of new fathers suffer from postnatal depression, compared with 10 per cent of women.
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