Xu, Shuman
Liang, Zhijiang
Du, Qiyun
Li, Zhankui
Tan, Guangming
Nie, Chuan
Yang, Yang
Lv, Xuzai
Zhang, Chunyi
Luo, Xianqiong
Funding for this research was provided by:
National Natural Science Foundation of China (71173055)
Article History
Received: 17 March 2017
Accepted: 6 February 2018
First Online: 14 February 2018
Ethics approval and consent to participate
: The studies were approved in written by the Medical Ethics Committee of Guangdong Women and Children Hospital. All the surveyed hospitals had been informed before the investigation and consented to be our participants with written permission.
: Not applicable.
: The authors declare that they have no competing interests.
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