Prenatal and perinatal risk factors for testicular cancer.

In an attempt to determine the risk factors responsible for the dramatic increases in testicular cancer incidence in young adults, mothers of testicular cancer cases and controls were questioned about in utero exposures, pregnancy-related conditions, and perinatal factors during their pregnancies with the 202 cases and the 206 controls. The strongest risk factor was low birth weight with a greater than 12-fold risk (confidence interval = 2.8 to 78.1) for subjects weighing 5 lb or less at birth compared to those who weighed over 5 lb. A statistically significant 2-fold increase in risk was associated with unusual bleeding or spotting during pregnancy, regardless of whether medication was taken for this condition. Other exposures during pregnancy associated with a statistically significant increase in risk were: use of "sedatives"; alcohol consumption; and exposure to X-rays. No excess risk was associated with the use of hormones during pregnancy. The findings for birth weight and abnormal uterine bleeding suggest that significant compromise of the normal maternal-fetal environment may be associated with subsequent increase in risk of testicular cancer. However, this increase in risk is not great enough to explain the dramatic increases in testicular cancer that have occurred in young adults.