Funding for this research was provided by:
Department of Health, Zhejiang Province, China (2013KYB149)
Zhejiang Health and Family Planning Commission, China (JSW2013-A013)
Natural Science Foundation of .China (81202067)
Article History
Received: 6 February 2019
Revised: 18 April 2019
Accepted: 7 May 2019
First Online: 12 May 2019
Compliance with ethical standards
: This study was conducted with the approval of the Institutional Review Board of Women’s Hospital, School of Medicine, Zhejiang University (IRB 20170135).
: The authors declare that they have no conflict of interest.