New U.K. research has found that daughters of fathers who experience postnatal depression are more likely to suffer from depression themselves during their teenage years.

Carried out by researchers at Imperial College London, University College London, the University of Oxford and the University of Bristol, the new study looked at 3,176 families to investigate the link between fathers' depression at eight weeks after the birth of their children and their children's risk of depression at age 18.

The researchers also included factors such as the mother's depression, the parent's involvement with their child, conflict between parents, and any behavioral problems in the children as well as hyperactivity at age 3.5 years.

The findings, published in JAMA Psychiatry, showed that there was a "small but significant" increased risk of depression for girls at age 18 if their fathers had experienced depression after their birth.

However, sons had no increased risk of depression.

It is unclear why girls may be affected at this age by paternal postnatal depression, but the researchers suggested that depression in either parent can disrupt family life and cause higher levels of stress for the whole family, as well as affecting the way in which parents interact with their children.

The specific aspects of a father-daughter relationship may explain why as girls go through adolescence, they have a higher risk of depression themselves if their fathers also suffered from depression.

Co-author Professor Paul Ramchandani said, "Research from this study of families in Bristol has already shown that fathers can experience depression in the postnatal period as well as mothers. What is new in this paper is that we were able to follow up the young people from birth through to the age of 18, when they were interviewed about their own experience of depression."

"We were also able to look at some of the ways in which depression in fathers might have affected children. It appears that depression in fathers is linked with an increased level of stress in the whole family, and that this might be one way in which offspring may be affected.

"Whilst many children will not be affected by parental depression in this way, the findings of this study highlight the importance of providing appropriate help to fathers, as well as mothers, who may experience depression."

The researchers also point out that almost one in 20 new fathers suffer depression in the weeks after their child is born.