[1] Chongqing Med Univ, Affiliated Hosp 1, Dept Obstet, Chongqing 400016, Peoples R China
[2] Chongqing Med Univ, Affiliated Hosp 1, Fetal Med Unit, Chongqing 400016, Peoples R China
[3] Chongqing Med Univ, Affiliated Hosp 1, Dept Ultrasound, Chongqing 400010, Peoples R China
[4] Beijing G Epigen Med Technol Inc, Beijing 101300, Peoples R China