Despite being one of the most common congenital defects in boys, the etiology of hypospadias remains largely unknown. In this case-referent study, we evaluated a wide spectrum of potential risk factors for hypospadias. Cases were identified from the hospital information system, and referents were recruited through the parents of the cases. Both parents of cases and referents completed written questionnaires that they received through the mail. Logistic regression analyses were used to assess the independent contribution of different factors to the risk of hypospadias. The final database included 583 cases and 251 referents. Hypospadias more often occurred in children whose father had hypospadias (OR=9.7; 95%CI: 1.3-74.0) and in children with a low birth weight (OR=2.3; 95%CI: 1.2-4.2). Indications for elevated risks were found when mothers were DES-daughters (OR=3.5; 95%CI: 0.8-15.6), fathers were subfertile (OR=1.8; 95%CI: 0.7-4.5), the parents had undergone fertility treatment (OR=2.3; 95%CI: 0.9-5.8), and in twin or triplet pregnancies (OR=2.0; 95%CI: 0.8-5.1). Maternal use of iron supplements (OR=2.2; 95%CI: 0.8-6.0), maternal smoking (OR=1.5; 95%CI: 1.0-2.4), paternal prescriptive drug use (OR=2.6; 95%CI: 1.1-6.6), and paternal exposure to pesticides (OR=2.1; 95%CI: 0.6-7.1) during the 3 months immediately prior to conception or in the first trimester of pregnancy also appeared to increase the risk of hypospadias. The associations found in this study support the hypothesis that genetic predisposition, placental insufficiency, and substances that interfere with natural hormones play a role in the etiology of hypospadias.

and proximal (43). Adjusted odds ratios (OR) with 95% confidence intervals (CI) were estimated using logistic regression. RESULTSLow birth weight, being a twin or triplet, mother being a diethylstilbestrol-daughter, fertility treatments, paternal subfertility, obesity, prescriptive drug use, and familial occurrence of hypospadias or testicular cancer were associated with hypospadias in general. For familial occurrence of hypospadias, there were high risk estimates for the distal and middle phenotypes with an OR (95%CI) of 10.4 (4.5-24.1) and 9.0 (3.1-26.0), but not for the proximal type at 1.8 (0.2-14.9). By contrast, the association with low birth weight (a proxy for placental dysfunction) seemed much stronger for proximal hypospadias with an OR (95%CI) of 9.1 (3.4-24.2) compared with distal and middle hypospadias at 2.6 (1.4-5.0) and 2.3 (0.8-6.5). There were similar estimates for pre-eclampsia. CONCLUSIONThese findings indicate aetiological heterogeneity of hypospadias and provide indications for the possible mechanisms through which specific risk factors may interfere with penile development. KEYWORDShypospadias, risk factors, endocrine disruptors, phenotype, severity Study Type -Aetiologic (case-referent) Level of Evidence 2a OBJECTIVETo obtain more insight into the origin of hypospadias by exploring a wide range of potential risk factors in a case-referent study in which a distinction was made between different phenotypes. PATIENTS AND METHODSCases and referents were 305 boys with hypospadias and 629 boys with middle ear effusion whose parents completed postal questionnaires. Hypospadias phenotype was classified as distal (195 boys), middle (67),

This study revealed potential risk factors for ARM, including fever during pregnancy, maternal overweight, use of multivitamins, paternal smoking, and occupational exposures, but a familial component seems important as well.

The results confirm an increased risk of hypospadias when mothers were exposed to DES in utero. However, the excess risk appears to be of much smaller magnitude than in the 2002 study. Further research on the potential health risks for the third generation is of great importance.

Despite some important limitations, this JEM could be a valuable tool for exposure assessment in studies on the health risks of endocrine disruptors, especially when task specific information is incorporated. The documented exposure scenarios are meant to facilitate further adjustments to the JEM to allow more widespread use.