1. Department of Preventive Medicine, Shenzhen Baoan Women's and Children's Hospital, Guangdong, China
2. Department of MCH Management, Shenzhen Baoan Women's and Children's Hospital, Guangdong, China
3. Department of Research, Shenzhen Baoan Women's and Children's Hospital, Guangdong, China
4. National Centre for Women and Children’s Health, China CDC, Beijing, China