Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China. zhiweichina@126.com. Department of Biochemistry and Molecular Biology, and Research Center of Clinical Laboratory Science, School of Laboratory Medicine, Bengbu Medical College, Anhui, China. zhiweichina@126.com. Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China. Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China. zjwzzxq@163.com. Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. wwei2@bidmc.harvard.edu.