1. Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
2. Department of Laboratory Medicine, Boramae Hospital, Seoul, Korea
3. Seoul Metropolitan Government Public Cord Blood Bank (Allcord), Seoul, Korea
4. Department of Biostatics4, Boramae Hospital, Seoul, Korea
5. Department of Obstetrics and Gynecology5, Boramae Hospital, Seoul, Korea