Funding for this research was provided by:
Shanghai Municipal Population and Family Planning Commission (201640057)
National Natural Science Foundation of China (81971315)
Received: 6 August 2019
Accepted: 14 October 2019
First Online: 15 November 2019
Ethics approval and consent to participate
: This study was approved by the Medical Ethics Committee (The First Affiliated Hospital, Sun Yat-sen University), and an exemption from informed consent was obtained from our responsible Investigational Ethics Review Board.
: Not applicable.
: The authors declare that they have no competing interests.