1. Department of Obstetrics and Puericulture, Faculty of Medicine; University of Concepción; Concepción Chile
2. Pelvic Floor Unit, Dr. Guillermo Grant Benavente Hospital; Concepción Chile
3. Service of Obstetrics and Gynecology, Hospital of Tomé; Tomé Chile
4. Department of Obstetrics and Gynecology, Faculty of Medicine; University of Concepción; Concepción Chile
5. Research Group on Public Health; University of Alicante; Alicante Spain
6. CIBER de Epidemiología y Salud Púbica; Madrid Spain