1. First Affiliated Hospital, Heilongjiang University of Chinese Medicine; Department of Obstetrics and Gynecology; No.26 Heping Road, Xiangfang District Harbin Heilongjiang China 150040
2. First Affiliated Hospital, Heilongjiang University of Chinese Medicine; Department of Internal Medicine; Heping Road 26, Xiangfang District Harbin Heilongjiang China 150040
3. West China Hospital, Sichuan University; Chinese Clinical Trial Registry, Chinese Ethics Committee of Registering Clinical Trials; No. 37, Guo Xue Xiang Chengdu Sichuan China 610041
4. University of Hong Kong, Queen Mary Hospital; Department of Obstetrics and Gynaecology; Pokfulam Road Hong Kong Hong Kong Hong Kong
5. National Key Discipline and Clinical Base, Heilongjiang University of Chinese Medicine; Department of Obstetrics and Gynaecology; Harbin China 150040