[1] Univ Porto, Serv Obstetr, Hosp Sao Joao, Fac Med,Ctr Prenatal Diag,Dept Gynecol & Obstet, PT-4200 Oporto, Portugal
[2] Univ Porto, Pediat Surg Unit, Hosp Sao Joao, Fac Med, PT-4200 Oporto, Portugal
[3] Univ Porto, Neonatol Unit, Hosp Sao Joao, Fac Med,Dept Pediat, PT-4200 Oporto, Portugal
[4] Univ Porto, Dept Otorhinolaryngol, Hosp Sao Joao, Fac Med,Cardiovasc R&D Unit, PT-4200 Oporto, Portugal
[5] SMIC, Imagiol, Oporto, Portugal