Parental separation or divorce is linked to a heightened risk of psychosomatic problems among the children in the family, indicates research published online in the Journal of Epidemiology & Community Health.
But joint custody seems to be less problematic than sole custody, the findings 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 in a nuclear family 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.
The prevalence of psychosomatic problems during the preceding 6 months was assessed using a validated scale (Psychosomatic Problems scale). The assessment focused on concentration and sleep difficulties; headaches; stomach aches; feelings of tension, sadness, and dizziness; and loss of appetite.
The teens were also asked if they could talk easily to their parent (s) when they needed to, and if they had enough money to do the same things as their friends.
Their 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.
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.
And the proportion of children who said they 'often' or 'always' had the different symptoms assessed on the scale was also highest among those who lived with just one parent.
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 wellbeing, were linked to the children's psychosomatic health, it could not explain the differences found among children in the various different domestic set-ups.
This is an observational study so no definitive conclusions can be drawn about cause and effect, and the researchers were not able to glean information about when the children had experienced family break-up. But their findings echo those of other studies, they say.
By way of an explanation for the differences noted between children living with one or both separated parents, the researchers emphasise that psychosomatic symptoms are related to stress, and living in two different homes could be stressful for children.
But this might be outweighed by the positive effects of maintaining close contact with both parents, they suggest.
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Fifty moves a year: is there an association between joint physical custody and psychosomatic problems in children? Journal of Epidemiology & Community Health, DOI: 10.1136/jech-2014-205058