Text and Data Mining valid from 2020-02-14
Received: 8 April 2019
Accepted: 27 January 2020
First Online: 14 February 2020
Ethics approval and consent to participate
: Ethics approval was granted by the Institutional Review Board, the University of Hong Kong/Hospital Authority, Hong Kong (IRB reference number UW 14–465) and Research Ethics Committee, Kowloon Central / Kowloon East, Queen Elizabeth Hospital (IRB reference number KC/KE-14-0212/FR-1). Informed written consent was obtained from all women who agreed to participate in the study.
: Not applicable.
: The authors declare that they have no competing interests.