Key factors in understanding differences in rates of birth defects identified

New research published in The Lancet highlights important information for health professionals and parents about the factors which may increase the likelihood of a baby being born with a birth defect. The findings, from researchers at the Universities of Bradford and Leeds, funded by the National Institute for Health Research (NIHR), confirm that the two main factors associated with an increased risk of babies being born with a birth defect are being born to an older mother or to parents who are blood relations. In addition, the research team was also able to confirm that socio-economic status (levels of deprivation) had no effect on the relative risk of birth defects, despite two-thirds of the mothers participating in the study coming 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. It has been known for some time that birth defects, also known as congenital anomalies, are a major cause of 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. Geneticist and lead author Dr Eamonn Sheridan, from the University of Leeds, says: “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.