Funding for this research was provided by:
Xi'an science and technology project, China (GG04137)
National nature science foundation of China (NSFC 81170294)
Clinical Research award of first Affiliated hospital Xi'an Jaiotong University, China (XJTU1AHCR2014-019)
Received: 17 January 2017
Accepted: 30 April 2018
First Online: 27 June 2018
Ethics approval and consent to participate
: The study was approved by the Ethics Committee of the 1st Affiliated Hospital of Xi’an Jiaotong University and all mothers gave their written informed consent.
: The authors declare that they have no competing interests.
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