Increasing prevalence of hypospadias in Western Australia, 1980-2000

Objectives: Hypospadias, a common birth defect, has shown widespread variation in reported rates and temporal trends across countries over the last 30 years. The aim of this study was to determine the prevalence and trends of hypospadias in an Australian population. Design: Population-based study of all male infants born in Western Australia (WA) between 1980 and 2000 diagnosed with hypospadias and notified to the WA Birth Defects Registry. Main outcome measures: Prevalence of hypospadias, birth outcome and association with other congenital anomalies, stratified by degree-of-severity. Results: 1788 cases of hypospadias were registered in WA in 1980-2000 with an overall prevalence of 34.8 (95% confidence interval (CI): 33.2 to 36.4) cases per 10000 births. The prevalence increased by 2.0% per annum (95% CI: 1.2% to 2.8%) from 27.9 in 1980 to 43.2 per 10000 births in 2000 ( p < 0.001). Hypospadias was mild in 84% of cases, moderate-severe in 11% and unspecified in 5%, with the number of moderate-severe hypospadias almost doubling over time ( p < 0.01). There were 1465 ( 82%) cases of isolated hypospadias and 323 (18%) had co-existing anomalies. Infants with co-existing genital (relative risk (RR) 4.5; 95% CI: 3.3 to 6.1) or non-genital (RR 1.5; 95% CI: 1.0 to 2.2) anomalies were more likely to have moderate-severe hypospadias compared with isolated cases. Conclusion: Hypospadias affects one in 231 births and has been reported to have increased significantly over the last 20 years. Future investigation of the aetiology of hypospadias is important to identify potentially modifiable risk factors and ensure optimal male reproductive health in the future.