1 Department of Obstetrics, Maternal and Child Health Care Hospital of Dongchangfu District, Shandong Province, Liaocheng City, 252000, China.
2 Delivery Room, Maternal and Child Health Care Hospital of Dongchangfu District, Shandong Province, Liaocheng City, 252000, China.
3 Department of Obstetrics, Maternal and Child Health Care Hospital of Dongchangfu District, Shandong Province, Liaocheng City, 252000, China. 19533012709@139.com.