University Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark; Departments of Physiology and Paediatrics, University of Turku, Finland.
Context: Recent studies showed that male reproductive health problems like cryptorchidism, hypospadias, testicular cancer and low sperm quality are more prevalent in Denmark than in Finland. Objectives: We hypothesized that if fetal testicular dysgenesis contributed to these observations, differences in gonadal development and the hypothalamus-pituitary-testis axis would already be detectable perinatally. Thus, we investigated healthy newborn boys in both countries. Design: Prospective, longitudinal population-based study. Setting: Two primary obstetric centers at the University Hospitals of Copenhagen, Denmark, and Turku, Finland Participants: 633 Danish / 1044 Finnish boys, born at term with appropriate weight for gestational age Interventions: ultrasound determination of testis size at 0-3-18 months and blood sampling (n = 727) at 3 months Main outcome measures: testicular volume, reproductive hormones Results: Testis volume was significantly higher at all ages in Finnish than in Danish boys (medians: 98 vs. 95 mm(3), 185 vs. 119 mm(3) and 188 vs. 136 mm(3), respectively, P