Funding for this research was provided by:
Changzhou science and technology support project (CE20175021)
key project of science and technology development fund of Nanjing Medical University (2017NJMUZD044)
Jiangsu Maternal and Child Health Research Projects (F201842)
Text and Data Mining valid from 2019-05-08
Received: 7 March 2019
Accepted: 1 May 2019
First Online: 8 May 2019
Ethics approval and consent to participate
: The study protocol was approved by the Institutional Review Board at Changzhou Maternity and Child Health Care Hospital. Informed consent was provided by all participants.
: Not applicable.
: The authors declare that they have no competing interests.
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