Article History
Received: 9 July 2020
Accepted: 16 November 2020
First Online: 6 January 2021
Compliance with Ethical Standards
:
: The authors declare that they have no conflict of interest.
: This research was carried out with the approval and supervision of the Ethics Committee ofZibo Maternal and Child Health Hospital and in line with the guidelines in Declaration of Helsinki.Written confirmed consent was acquired from each respondent.