1. Department of Nursing, Shunde Women and Children's Hospital, Shunde, Guangdong 528300, P.R. China
2. Department of Pediatrics, Shunde Women and Children's Hospital, Shunde, Guangdong 528300, P.R. China
3. Department of Neonates, Shunde Women and Children's Hospital, Shunde, Guangdong 528300, P.R. China