Maternal reproductive and demographic characteristics as risk factors for hypospadias.

This study examined the association of hypospadias risk with several maternal reproductive and demographic characteristics: age, parity, body mass index (BMI), nausea and vomiting of pregnancy (NVP), multiple pregnancy, fertility treatments and procedures, education and race-ethnicity. The study included data on deliveries with estimated due dates from October 1997 to December 2000 that were part of the National Birth Defects Prevention Study, a multi-state case-control study of many birth defects. The analysis included 502 cases with second or third degree hypospadias (i.e. the urethra opened at the penile shaft, scrotum or perineum) and 1286 male, liveborn, non-malformed controls. Risks were estimated from a multivariable logistic regression model that included all exposures of interest. Results indicated particularly elevated risks among births to women who were primiparae, aged >or=35 years and had a BMI of >26, compared with women who were multiparae, aged <30 years and had a BMI of