1. Department of Obstetrics and Gynaecology; Yong Loo Lin School of Medicine, National University Health System, National University of Singapore; Singapore 119228 Singapore
2. Department of Surgery; Yong Loo Lin School of Medicine, National University Health System, National University of Singapore; Singapore 119228 Singapore
3. Department of Biochemistry; Yong Loo Lin School of Medicine, National University Health System, National University of Singapore; Singapore 119228 Singapore