1. Department of Obstetrics and Gynecology; Hospital General Gregorio Marañón, Universidad Complutense de Madrid; Madrid Spain
2. Department of Obstetrics and Gynecology; Hospital Central de la Defensa Gómez Ulla, Universidad de Alcalá de Henares; Madrid Spain
3. Research Support Unit; Hospital General La Mancha Centro; Alcázar de San Juan Ciudad Real Spain
4. Department of Pediatric Cardiology; Hospital General Gregorio Marañón, Universidad Complutense de Madrid; Madrid Spain