Funding for this research was provided by:
“Gaoyuan” project from Pudong Health and Family Planning Commission (PWYgy2018-06)
Received: 10 May 2019
Accepted: 11 June 2019
First Online: 21 June 2019
Ethics approval and consent to participate
: The study was approved by the Shanghai Jiaotong University Xinhua Hospital Ethics Committee (XHEC2011-002).
: Not applicable
: The authors declare that they have no competing interests.