Risk factors for undescended testis

ObjectiveTo contribute to the understanding of the etiology of undescended testis (UDT), by exploring a wide range of potential risk factors in a case-referent study.Patients and methodsCases and referents were recruited at five hospitals and included 200 boys with surgically corrected UDT and 629 boys with persistent middle ear effusion. Risk factor data were obtained by postal questionnaires to both parents. Clinical data were collected from medical files. Adjusted odds ratios (OR) with 95% confidence intervals (CI) were estimated using logistic regression.ResultsThe main findings include associations between UDT and familial occurrence of the disorder: OR 3.1 (95%CI 1.9–4.9), low birth weight: 2.2 (1.1–4.3), twinning: 2.2 (0.9–5.4), gestational preeclampsia: 1.9 (0.8–4.4), use of oral contraceptives after conception: 3.6 (1.0–12.5), in vitro fertilization/intracytoplasmic sperm injection treatment: 2.2 (0.8–6.0), paternal subfertility: 1.8 (0.8–4.1), and maternal occupational exposure to cosmetics: 3.0 (0.9–10.0). Subgroup analyses indicated differences in ORs for several factors between cases with (n = 92) and without (n = 103) inguinal hernia or hydrocele.ConclusionThe findings point towards a role for genetic predisposition, placental insufficiency, and possibly exposure to specific endocrine disrupting substances in the etiology of UDT. Further research should take into account potential etiologic differences between subgroups of cases with UDT.