Causes and Rates of Occurrence

The causes and rates of incidence of hypospadias have not yet been definitively defined by researchers. Past studies have been small and samples have not been representative of the general population. Official reporting on hypospadias has been spotty. The news media has tended to pick up these poorly-done studies and mis-state their conclusions while exaggerating their importance. That said, we’re pretty confident that the following information is correct.

Hypospadias can occur in generations of families in a classic hereditary pattern and also as isolated cases. Most hypospadias is isolated, so while it can be passed down, it is not necessary to have a relative with hypospadias for there to be a possibility it will occur. Estimates are that there is an 8% increased risk of hypospadias if the father is affected, and 12% increased risk if an older sibling is also hypospadic. Please note that this is NOT an 8 or 12 percent risk of hypospadias in any random birth. It is an estimate of the increase in the overall background risk of bearing a child with hypospadias.

Overall estimates of the rate of occurence of hypospadias range from 1 in 300, to 1 in 125 live births, and like any other human demographic, the numbers change by location, accuracy of record keeping, consistency in classification of the difference and so on. While there is some difference in rates by race, the differences are not statistically significant. Hypospadias occurs in all races and ethnicities. Some researchers have concluded that hypospadias is increasing. Others have not reached that conclusion, pointing to inconsistent reporting of hypospadias in the past, and natural fluctuations in annual statistics.

Some things we don’t know about hypospadias:

  • There is a lot of internet content on pesticides, pthalates, phytoestrogens, DES, prescription drugs, industrial pollution and so on, and the hypothetical effects on birth defects. While we do know that certain prescription drugs can cause hypospadias, the links between hypospadias and other substances in the environment have not been proven. At this time, there is no proven single cause for hypospadias, and since hypospadias is highly variable in form and occurence, it is likely that it is caused by multiple factors.