[1] Hosp Gen Univ Gregorio Maranon, Madrid 28007, Spain
[2] Univ Complutense Madrid, Hosp Gen Univ Gregorio Maranon, Dept Salud Publ & Materno Infantil, Serv Cuidados Intens Pediatr, Madrid 28040, Spain
[3] Inst Salud Carlos III, Primary Care Intervent Prevent Maternal & Child C, Madrid 41092, Spain
[4] Hosp Valle De Hebron, Barcelona 08035, Spain
[5] Hosp Doce Octubre, Madrid 28041, Spain
[6] Hosp Clin Univ Virgen Arrixaca, Murcia 30120, Spain
[7] Hosp Univ Cent Asturias, Oviedo 33011, Spain
[8] Hosp Univ Nuestra Senora Candelaria, Tenerife 38010, Spain
[9] Hosp Univ Cruces, Bilbao 48903, Spain
[10] Complejo Hosp Navarra, Pamplona 31008, Spain
[11] Hosp Univ Ramon & Cajal, Madrid 28034, Spain
[12] Univ Complutense Madrid, Fac Med, Dept Salud Publ & Maternoinfantil, Madrid 28040, Spain