Funding for this research was provided by:
National Key Technology Research and Development Program of China (2012BAI32B02)
National Science and Technology Infrastructure Program of China (2013FY110500)
Innovation-oriented Science and Technology Grant from NHC Key Laboratory of Reproduction Regulation (CX2017-05)
Received: 17 May 2018
Accepted: 18 December 2018
First Online: 3 January 2019
Ethics approval and consent to participate
: We provided information sheets about the study to all the students and their teachers and guardians 1 week before the survey, the sheets highlighted that this survey was anonymous and the students were free to skip some questions and even quit the survey if they felt uncomfortable. Written informed consent was obtained from the guardians of all students. Verbal consent was obtained from the students before the examination. This study was reviewed and approved by the institutional review board of Shanghai Institute of Planned Parenthood Research (2012–01).
: Not applicable.
: The authors declare that they have no competing interests.
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