1 Department of Gynecology, Center for Reproductive Medicine, Zhejiang Provincial People's Hospital (People's Hospital of Hangzhou Medical College), Hangzhou, Zhejiang Province (Drs. Bai, J. Wang, and Y. Wang).
2 Department of postgraduate education, Jinzhou Medical University, Jinzhou, Liaoning Province (Drs. He, Liu, and Y. Wang), China.
3 Department of Gynecology, Center for Reproductive Medicine, Zhejiang Provincial People's Hospital (People's Hospital of Hangzhou Medical College), Hangzhou, Zhejiang Province (Drs. Bai, J. Wang, and Y. Wang); Department of postgraduate education, Jinzhou Medical University, Jinzhou, Liaoning Province (Drs. He, Liu, and Y. Wang), China. Electronic address: wangyanpeng@hmc.edu.cn.