1. Department of Obstetrics and GynecologyZhongnan Hospital of Wuhan University Wuhan Hubei P. R. China
2. Hubei Clinical Research Center for Prenatal Diagnosis and Birth Health Wuhan Hubei P. R. China
3. Key Laboratory of Artificial Micro‐ and Nano‐structures of Ministry of EducationSchool of Physics and TechnologyWuhan University Wuhan Hubei P. R. China
4. Department of Blood TransfusionZhongnan Hospital of Wuhan University Wuhan Hubei P. R. China