The challenge
It has been known for some time that birth defects, also known as congenital anomalies, are a major cause of illness and disability including infant mortality and that their incidence varies across ethnic groups in the UK. Other studies in the last 20 years have considered consanguinity (marriage to a blood relation), as a cause of birth defects, but these studies weren’t able to rule out other potential risk factors, particularly the effects of deprivation.
What we are doing about it
The study is the largest of its type ever conducted. The team examined detailed information collected about more than 11,300 babies involved in the Born in Bradford project.
What we found
The two main factors associated with an increased risk of babies being born with a birth defect are: • being born to an older mother • being born to parents who are blood relations. The research team found that the overall rate of birth defects in the BiB babies was approximately 3% – nearly double the national rate. However, it is important to note that the vast majority of babies born to couples who are blood relatives are healthy, and whilst consanguineous marriage increases the risk of birth defect from 3% to 6%, the absolute risk is still small. It is also important to remember that consanguinity only accounts for a third of birth defects. • The research team found that socio-economic status (levels of deprivation) had no effect on the relative risk of birth defects • They also found that higher levels of education amongst mothers halved the risk of having a baby with a defect across all ethnic groups.
Changes that have been implemented as a result of this work
In Bradford, there are initiatives that seek to raise community awareness and services such as genetic counselling and testing are in place that can be accessed by couples who are married or considering marriage to a blood relative. We want to ensure that couples are aware of any risks so that they can make informed choices when planning their families. We have shared our findings very widely across the UK and the world because the sorts of things we have found in Bradford are of importance to any community where it is customary to marry a blood relation. We are also looking at the sorts of help that is available to families when they do have a child with a birth defect so we can advise about what is most problematic to them and look at where organisations can be most helpful to them.
Things we need to find out
We don’t fully understand why mother’s education seems to have an effect and we need to look in more detail at this. We need to look at any other health effects of being in a consanguineous marriage; these might be positive as well as negative. We also need to look at patterns of birth defects in families and in other groups in society.
Link to full research
You can read more about this research in the following paper:
- Sheridan, E., Wright, J., Small, N., Corry, P. C., Oddie, S., Whibley, C., et al. (2013). Risk factors for congenital anomaly in a multiethnic birth cohort: an analysis of the Born in Bradford study. The Lancet, 382(9901), 1350-1359.
