1 Chengdu Women's and Children's Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, 611731, China.
2 School of Public Health, Curtin University, Perth, Australia.
3 Chengdu Jinjiang Maternity and Child Health Hospital, Chengdu, China.
4 Chengdu Women's and Children's Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, 611731, China. cdlcr@163.com.