Cryptorchidism, and epidemiologic study with emphasis on the relationship to central nervous system dysfunction.

This case-control study examines the relation of cryptorchidism to central nervous system dysfunction. Elevated odd ratios were found for cerebral palsy (RR = 34), low IQ (RR = 2.7), and low motor function measured by the Bayley test (RR = 3.6). Low IQ and cerebral palsy were independent risk factors for cryptorchidism. Breech labor (RR = 2.6), a gestation less than 34 weeks (RR = 2.0), and being a twin (RR = 4.1) were also independent risks. Other risk factors were estrogen use by the mother (RR = 3.3) and a maternal Quetelet index less than 24 (RR = 1.6). All of these risks were statistically significant. These factors suggest that cryptorchidism may be caused either by sex steroid action directly on the testes or by CNS damage, which in turn causes suppression of pituitary gonadotropins. The increased occurrence of cryptorchidism in twins and small babies indicates that retarded general fetal development can be another mechanism for maldescent of the testes.