Funding for this research was provided by:
National Key Research and Development Program, Ministry of Science and Technology, P.R. China (2016YFC1000500)
National Natural Science Foundation of China (81373014)
National Natural Science Foundation of China (81202265)
Article History
Received: 25 July 2018
Accepted: 22 November 2018
First Online: 12 December 2018
Ethics approval and consent to participate
: The project was approved by the institutional review boards of the US Centers for Disease Control and Prevention and Peking University Health Science Center. All women who took pills provided oral informed consent.
: Not applicable.
: The authors declare that they have no competing interests.
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