Parental separation or divorce is linked to a heightened risk of psychosomatic problems among the children in the family, new research has indicated.

But joint custody seems to be less problematic than sole custody, the findings in the Journal of Epidemiology & Community Health suggest.

Over the past 20 years, family break-up has become more common in developed countries, with an increasing tendency to award joint legal custody afterwards. In Sweden alone, joint custody has surged from 1-2% of children affected by divorce/separation during the 1980s to 40% in 2010.

Previous research has suggested that children whose parents have split up are more prone to emotional and behavioural problems than those who live with two co-habiting parents.

The researchers therefore used data from a national classroom survey of almost 150,000 Swedish 12- and 15-year-olds in a bid to see if children's domestic living arrangements were linked to a heightened risk of psychosomatic problems.

Domestic living arrangements were categorised as living mostly or only with one parent after separation/divorce; alternating between parents as part of a joint custody agreement; and living with both parents in a nuclear family.

Girls have more problems than boys

The analysis showed that girls reported more psychosomatic problems than boys at both ages, although the researchers caution that girls generally report more psychosomatic ill health than boys.

But teens living mostly with one parent as a result of family break-up reported the most psychosomatic problems, while those living with both parents in a nuclear family set-up reported the fewest.

"The practice of joint physical custody – that is, children spending equal time in the respective homes of their separated parents – has become more frequent in Western countries over the past decade," the researchers said.

"At the same time, there has been an increase in self-reported paediatric psychosomatic 

"Child health experts have argued that joint physical custody imposes stress [compared to a nuclear family set-up]."

The study, led by the Centre for Health Equity Studies (Chess) at Stockholm University/Karolinska Institutet, is published in the Journal of Epidemiology & Community Health.

Dr Malin Bergstrom, of Chess, said: "Children living in joint custody arrangements had fewer psychosomatic problems than their peers living mostly or only with one parent, but they still had more than children living with both parents in a nuclear family. These findings held true even after taking account of influential factors, such as age and country of origin.

"And while the quality of the relationship they had with their parents, and their material well-being, were linked to the children's psychosomatic health, it could not explain the differences found among children in the various different domestic set-ups."