YOUNGSTERS who climb into bed with their parents have an increased risk of asthma in later childhood, a study has found.

The same association was not seen in bed-sharing infants, say researchers who were unable to provide a clear explanation for their findings.

One theory, that parents who notice wheezing symptoms in their children are more likely to keep them close by at night, was not confirmed by analysis.

The study of 6,160 mothers and their children in Rotterdam, the Netherlands, showed no link between babies sleeping with parents and an increased risk of wheezing or asthma in the first six years of life.

But bed-sharing at the age of two led to a 42% higher chance of wheezing symptoms at age three to six, and a 57% greater likelihood of being diagnosed with asthma at age six.

The researchers gathered information on children's wheezing and asthma symptoms every year from the age of one to six.

They also assessed sleeping patterns using a parental questionnaire. Bed-sharing was defined as a child sharing a bed with either the mother or both parents.