The study, from the University of Bristol's Children of the 90s project, which is published in The Lancet today confirms that postnatal depression affects a significant number of fathers.
Baby boys, who seem to be particularly affected if their fathers are depressed, go on to have twice as many behavioural problems in the preschool years.
Researchers from the Universities of Oxford, Bristol and Rochester in the United States analysed records on 8,430 fathers and found that eight weeks after the birth, 3.6 per cent (303) appeared to be suffering from depression, with symptoms including anxiety, mood swings, irritability and feelings of hopelessness.
In line with previous studies, 10.2 per cent of mothers had similar signs of depression.
Oxford psychiatrist Dr Paul Ramchandani says: "We already know that postnatal depression in mothers can affect the quality of maternal care, and is associated with disturbances in children's later social, behavioural, psychological and physical development.
"While a significant number of men do report depression following the birth of a child, until now the influence of depression in fathers during the early years of a child's life has received scant attention.
"There is research establishing that adolescent children of depressed fathers have higher rates of psychiatric disorder but very little is known about the possible effects of paternal depression early in children's lives."
At the age of 3½, the children were assessed for both emotional symptoms (such as worry and sadness) and behaviour (including hyperactivity).
The researchers found that in families where the fathers had been suffering from depression soon after the birth - the children were twice as likely to have high levels of emotional and behavioural problems.
When they looked separately at boys and girls, there was a significant difference in boys' behaviour if their fathers had been depressed. Fewer girls were affected.
Dr Ramchandani says: "The relationship between boys' behavioural development and depression in their fathers is striking. It may be that boys are specifically sensitive to the effects of parenting by fathers, perhaps because of different involvement by fathers with their sons.
"The influence of fathers in very early childhood may have been under-estimated in the past, but these findings indicate that paternal depression has a specific and persisting impact on children's early behavioural and emotional development and that fathers influence their children's development from very early in life.
"Although largely neglected to date, paternal depression in the postnatal period should be recognised and treated by healthcare professionals in order to lessen any adverse effects on the child."
Paper:
Paternal depression in the postnatal period and child development: a prospective longitudinal study. Paul Ramchandani, Alan Stein, Jonathan Evans, Thomas G. O'Connor and the ALSPAC study team . The Lancet, June 25 2005