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Objectives: Previous studies have reported an association between subfertility and the risk of testicular germ cell tumors. We examined fertility, measured by number of children fathered and prior diagnosis of infertility, as a risk factor for testicular cancer, while accounting for the influence of occult cancer and cryptorchidism., Methods: Tumor registry data were used to identify 329 cases of testicular cancer in white men aged 20 to 69 years, diagnosed in western Washington State from 1977 to 1983; 672 cancer-free controls were identified by random-digit dialing. Telephone interviews ascertained reproductive histories and basic demographic information. Logistic regression was used to estimate the relative risk of testicular cancer associated with fertility., Results: Testicular cancer risk was decreased among men who had previously fathered a child (age-adjusted odds ratio (OR) 0.76, 95% confidence interval (CI): 0.54-1.06). Inverse associations were seen for seminomas and non-seminomas, and only slight attenuations in the ORs were observed when men with a history of cryptorchidism were excluded. Prior diagnosis of infertility was associated with an increased risk of testicular cancer (OR 2.40, 95% CI: 1.00-5.77)., Conclusions: These results are consistent with an increased risk of testicular cancer among men with reduced fertility that goes beyond the effects of cryptorchidism.

Interpretation of studies that have examined parity as a risk factor for Down's syndrome has been hindered by inadequate control for maternal age and/or failure to account for the differential use of prenatal diagnosis and pregnancy termination between low-parity and high-parity women. In this case-control study, the authors used exact matching on maternal age-minimize confounding and evaluated the potential impact of differential termination. A total of 898 cases of Down's syndrome and 4,488 controls were identified using Washington State birth certificates from 1984-1998. There was a trend towards increasing risk of Down's syndrome with increasing parity in both younger (age <35 years) and older (age > or =35 years) mothers. Restriction to women with no indication of amniocentesis (for whom differential termination is unlikely) resulted in a blunting of the odds ratios; however, a trend for parity remained. After restriction, odds ratios were as high as 1.65 (95% confidence interval: 1.13, 2.40) in younger women with a parity of three (compared with a parity of zero) and 2.41 (95% confidence interval: 1.41, 4.12) in older women with a parity of four or more. Although the odds ratios for older women were probably biased upwards because of underreporting of amniocentesis on birth certificates, these data support an association between parity and Down's syndrome.