Prevalence of hypospadias in Danish boys: a longitudinal study, 1977-2005.

BACKGROUND

Hypospadias is a relatively common congenital malformation. Data on temporal trends in prevalence of hypospadias are conflicting. It is unclear whether changes of maternal age distribution over time are associated with changes in hypospadias prevalence.

OBJECTIVE

To study changes in prevalence of hypospadias in Denmark during a 29-yr period and to investigate whether maternal age was associated with the prevalence of hypospadias.

DESIGN, SETTING, AND

PARTICIPANTS

Through Denmark's National Patient Registry, covering all Danish hospitals, we identified all boys diagnosed with hypospadias in Denmark. From the Danish Medical Birth Registry, we obtained information on maternal age and on the annual total number of live-born boys from 1977 to 2005.

MEASUREMENTS: Prevalence of hypospadias at birth.

RESULTS AND LIMITATIONS: Among 921745 boys born alive from 1977 to 2005, we identified 3490 boys with hypospadias. The prevalence increased from 0.24% in 1977 to 0.52% in 2005, corresponding with an annual increase in prevalence of 2.40% (95% confidence interval: 1.94-2.86). The prevalence of hypospadias did not differ according to maternal age. The mean annual prevalence was 0.38% in sons of mothers aged <or=25 yr, 0.37% in sons of mothers aged 26-30 yr, 0.39% in sons of mothers aged 31-35 yr, and 0.39% in sons of mothers >35 yr.

CONCLUSIONS

The hypospadias prevalence was increasing in Denmark from 1977 to 2005. Increased maternal age did not explain this trend.