1. Department of Pathology, Tongzhou Maternal and Child Health Hospital of Beijing, Beijing, China.
2. Department of Galactophore, Tongzhou Maternal and Child Health Hospital of Beijing, Beijing, China.
3. Department of Gynaecology, Tongzhou Maternal and Child Health Hospital of Beijing, Beijing, China.
4. Department of Obstetrics, Tongzhou Maternal and Child Health Hospital of Beijing, Beijing, China.