Funding for this research was provided by:
National Key Research and Development Program (2018YFC1004000)
Received: 7 October 2019
Accepted: 22 January 2020
First Online: 1 February 2020
Ethics approval and consent to participate
: This study has approved by the Reproductive Study Ethics Committee at Peking University Third Hospital. Participants were fully informed and they granted consent for their children involved in the study. Written informed consent was obtained from all patients.
: Not applicable.
: The authors declare that they have no competing interests.