[1] Univ Bern, Inst Social & Prevent Med, Mittlestr 43, CH-3012 Bern, Switzerland
[2] Lausanne Univ Hosp, Dept Women Mother Child, Serv Paediat, Rue Bugnon 21, CH-1011 Lausanne, Switzerland
[3] Univ Lausanne, Rue Bugnon 21, CH-1011 Lausanne, Switzerland
[4] Univ Bern, Grad Sch Hlth Sci, Mittlestr 43, CH-3012 Bern, Switzerland
[5] Univ Bern, Childrens Univ Hosp Bern, Paediat Resp Med, Freiburgstr, CH-3010 Bern, Switzerland