Trends in the incidence of cryptorchidism and hypospadias and methodological limitations of registry-based data

Cryptorchidism and hypospadias share possible risk factors, such as intraut erine growth retardation. According to the data collected by the Internatio nal Clearinghouse for Birth Defects Monitoring Systems (ICBDMS), apparently increasing trends in the incidence of hypospadias were found in Sweden dur ing the 1960s, and in Norway, Denmark, England and Hungary during the 1970s , In Norway and Denmark, the increase continued in the 1980s, while in the USA it has continued from the 1970s to the 1990s, Finland has shown a lower reported rate of hypospadias than other Nordic countries. However, it is d ifficult to make comparisons between countries because of variable inclusio n criteria. Furthermore, the reliability of the data depends on correct asc ertainment and reporting of the cases. The ICBDMS has also collected data o n cryptorchidism, but these appear to be unreliable because of a discrepanc y with the data from cohort studies, According to two comparable English st udies, the incidence of cryptorchidism in fullterm boys approximately doubl ed between the 1950s and the 1980s, Regionally there are large differences: e,g, in Finland the incidence of cryptorchidism is clearly lower than in D enmark. Regional and temporal trends may help to identify environmental fac tors that might be associated with these disorders.