Born in Bradford is a long-term study which is following the health of babies who were born in Bradford Royal Infirmary between 2007 and 2011.
It revealed being born to older parents, or parents who are blood relatives, can increase the risk of birth defects.
In the Pakistani subgroup, 77% of babies born with birth defects were to parents who were relatives. In the White British group 19% of babies with an anomaly were born to mothers over the age of 34.
"In Bradford, there are initiatives that seek to raise community awareness and services such as genetic counselling and testing in place that can be accessed by couples who are married or considering marriage to a blood relative. It is not our intention to counsel couples about who they choose to marry. But we do want to ensure that couples are aware of any risks so that they can make informed choices when planning their families."
– Professor Neil Small, University of Bradford, co-author of the study
A report done at the Universities of Leeds and Bradford has identified being born to older parents and being born to parents who are blood relatives increases the risk of birth defects.
"It is important to note that the vast majority of babies born to couples who are blood relatives are absolutely fine, and whilst consanguineous marriage increases the risk of birth defect from 3% to 6%, the absolute risk is still small. We should also remember that consanguinity only accounts for a third of birth defects."
– Geneticist and lead author of "Born in Bradford", Dr Eamonn Sheridan, University of Leeds
New research done at the Universities of Leeds and Bradford says there are two main factors which contribute to birth defects.
The report - "Born in Bradford" - shows these are being born to an older mother or to parents who are blood relations.
In addition, the research team established that higher levels of deprivation had no effect on the risk of birth defects. Two-thirds of the mothers participating in the study came from the most deprived fifth of the British population.
The data also showed that higher levels of maternal education halved the risk of having a baby with a defect across all ethnic groups.