Representing risks

In 2013, a leading British medical journal the Lancet published a research report about the risk factors for congenital abnormality. Congenital anomalies, also known as birth defects, are structural deformities that develop in the uterus or arise from birth or neonatal trauma. Although 'congenital' implies 'inborn', these anomalies are not always genetic in origin, but have chromosomal, genetic and environmental causes. The article was based on analysis of data from a multi-ethnic cohort of 13,776 babies born in Bradford, Yorkshire, between 2007 and 2011. The authors were interested in understanding why there are ethnic differences in rates of congenital anomaly. They sought to identify associations with known risk factors, specifically poverty, maternal age, educational level, parental consanguinity, alcohol consumption and smoking behaviour.

Such questions are particularly significant in Bradford, one of the UK's poorest cities, and home to around ten percent of England's Pakistani Muslim population. In the UK overall, rates of infant death and childhood illness are highest in babies of Pakistani ethnicity, and most of this mortality and morbidity is due to congenital anomalies. The Bradford researchers found that, according to the study, the highest proportion of congenital anomalies were seen in the 5127 babies born to Pakistani parents. They also observed that 60 percent of the Pakistani babies had parents who were consanguineous – related as second cousins or closer – and 37 percent had first-cousin parents. In the analysis of risk factors, parental consanguinity was associated with about one-third of the anomalies in Pakistani babies. Overall, it doubled the two percent background risk for congenital anomaly, and its effect was independent of poverty. This risk level was determined to be similar to the risk associated with mothers of white British origin over 34 years old.