Socio-occupational status and congenital anomalies.

"Conflicts of interest : None declared."

"Funding Danish Research Agency (No. 1105-93 and 11099-96); Danish National Birth Cohort is obtained from the Pharmacy Foundation, the Egmont Foundation, the March of Dimes Birth Defects Foundation and the Augustinus Foundation. Conflicts of interest: None declared. Key pointsWe investigate the association between socio-occupational status differences and overall and specific major congenital anomalies.The prevalence of all recorded major congenital anomalies was similar in all the socio-occupational categories.We observed an association between low socio-occupational status and congenital anomalies of the respiratory system."

"By using the mother's central identification number, we retrieved information about all pregnancy outcomes in the National Discharge Register and the National Birth Register. In the Central Registration System, we linked the mother's identification number to the child's identification number and identified all children with CAs codes DQ00.0 to 99.9 of the International Classification of Disease 10th version (ICD-10) at birth or during the first year of life. We divided them into categories according to the European Surveillance of Congenital Abnormalities Classifications (EUROCAT) criteria (part 7 of the former EUROCAT Guide 1.2.). CAs were classified into subgroups after excluding minor CAs with lesser medical, functional or cosmetic importance, as defined by EUROCAT."