[1] PanHellen Assoc Continual Med Res, Sect Obstet & Gynecol, Athens, Greece
[2] PanHellen Assoc Continual Med Res, Sect Dent & Oral Hlth, Athens, Greece
[3] PanHellen Assoc Continual Med Res, Sect Publ Hlth, Athens, Greece
[4] Univ Milan, Inst Stat Med & Biometria, Milan, Italy