Socioeconomic inequalities in risk of congenital anomaly
- aEnvironmental Epidemiology Unit, Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK, bGlasgow Eurocat Register, Paediatric Epidemiology and Community Health Unit, Department of Child Health, University of Glasgow, Scotland, UK, cNorth Thames (West) Congenital Malformation Register, Department of Medical and Community Genetics, Imperial School of Medicine, Northwick Park Hospital, Harrow, UK, dNational Downs Syndrome Cytogenetic Register, The Wolfson Institute of Preventive Medicine, St Bartholomew's and the Royal School of Medicine and Dentistry, London, UK, eNorthern Congenital Abnormality Survey, Maternity Survey Office, University of Newcastle-upon-Tyne, UK
- Ms Vrijheid email:
- Accepted 4 February 2000
AIMS To investigate socioeconomic inequalities in the risk of congenital anomalies, focusing on risk of specific anomaly subgroups.
METHODS A total of 858 cases of congenital anomaly and 1764 non-malformed control births were collected between 1986 and 1993 from four UK congenital malformation registers, for the purposes of a European multicentre case control study on congenital anomaly risk near hazardous waste landfill sites. As a measure of socioeconomic status, cases and controls were given a value for the area level Carstairs deprivation index, by linking the postcode of residence at birth to census enumeration districts (areas of approximately 150 households).
RESULTS Risk of non-chromosomal anomalies increased with increasing socioeconomic deprivation. The risk in the most deprived quintile of the deprivation index was 40% higher than in the most affluent quintile. Some malformation subgroups also showed increasing risk with increasing deprivation: all cardiac defects, malformations of the cardiac septa, malformations of the digestive system, and multiple malformations. No evidence for socioeconomic variation was found for other non-chromosomal malformation groups, including neural tube defects and oral clefts. A decreasing risk with increasing deprivation found for all chromosomal malformations and Down's syndrome in unadjusted analyses, occurred mainly as a result of differences in the maternal age distribution between social classes.
CONCLUSION Our data, although based on limited numbers of cases and geographical coverage, suggest that more deprived populations have a higher risk of congenital anomalies of non-chromosomal origin and some specific anomalies. Larger studies are needed to confirm these findings and to explore their aetiological implications.