[1] Seoul Natl Univ, Coll Med, Dept Lab Med, Seoul 110744, South Korea
[2] Seoul Natl Univ, Boramae Hosp, Dept Lab Med, Seoul 156707, South Korea
[3] Seoul Metropolitan Publ Cord Blood Bank, Seoul 156707, South Korea
[4] Seoul Natl Univ, Boramae Hosp, Dept Pediat, Seoul 156707, South Korea
[5] Seoul Natl Univ, Boramae Hosp, Dept Obstet & Gynecol, Seoul 156707, South Korea