Health Update: Relative risks

FIRST cousins who marry run a one in 10 risk of having a child with a severe abnormality - three times higher than in the general population, say researchers at Birmingham Maternity Hospital. In a six-year study involving nearly 5,000 babies, they found that those born to blood relations had a 1 per cent risk of early death because of congenital malformation; a 2 per cent risk of death before five; and a 7 per cent risk of severe disabilities.

The risks arise because most such marriages follow similar relationships in earlier generations, they say in General Practitioner.