About the Authors

Pingde Zhang

Affiliation Department of Obstetrics and Gynecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, People's Republic of China

Stephanie Si Liu

Affiliation Department of Obstetrics and Gynecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, People's Republic of China

Hextan Yuen Sheung Ngan

gyonc@hku.hk

Affiliation Department of Obstetrics and Gynecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, People's Republic of China

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: PZ SSL HYN. Performed the experiments: PZ. Analyzed the data: PZ SSL HYN. Contributed reagents/materials/analysis tools: SSL HYN. Wrote the paper: PZ SSL HYN.