British Pakistani couples warned of birth defect risk
4 July 2013 Last updated at 15:38 BST
More than half of British Pakistani children born Bradford between 2007-2011 were born to parents who were blood relatives.
Yet new research from the Universities of Bradford and Leeds found that children who were born in cousin marriages were twice as likely to be born with a birth defect.
Dr. Rafaqut Rashid is a GP based in Bradford and believes more information is needed for British Pakistani couples concerned about starting a family.
He told BBC Radio 5 live's Victoria Derbyshire, "If you look around you and see that there's been a number of cousin marriages within your family and very clearly there's been no evidence of congenital anomalies... it doesn't seem to be an immediate risk."