Text and Data Mining valid from 2019-06-07
Received: 5 September 2018
Accepted: 27 May 2019
First Online: 7 June 2019
Ethics approval and consent to participate
: The study complied with the Declaration of Helsinki and was reviewed and approved by the Human Subjects Committee of Changzhou No. 2 People’s Hospital approved this study. Written informed consent was obtained from each couple enrolled in the study.
: This manuscript does not include any individual person’s data.
: The authors declare that they have no competing interests.