Aetiological factors in hypospadias.

Epidemiological and genetic variables in hypospadias were analysed during the years 1978 to 1983 in a case control study of congenital malformations in the Emilia Romagna region of northern Italy. During the observation period, in a sample of 41 078 male newborns, 168 had hypospadias giving a prevalence at birth of 4.1 in 1000 males. Hypospadias was divided into three types: type I or mild (75.0%); type II or moderate (21.4%); and type III or severe (3.6%). Coexisting malformations were found in 8.9% of cases. The heritability coefficient was 0.669. Maternal risk factors correlated with hypospadias were found to be early age at menarche, threatened abortion, and exposure to progestins. Low birth weight and shorter gestation were also correlated with hypospadias.