1. Reproductive Medical Center (L.F., Y.-P.S.), The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China 450052
2. Department of Obstetrics and Gynaecology (L.F., H.-M.C., J.-C.C., P.C.K.L.), Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4