Subjects
We conducted a cross-sectional study on pregnant women in late pregnancy who had their first visit to the Department of Obstetrics and Gynecology, Tianjin Medical University General Hospital from November 2019 to July 2020. Inclusion criteria: 18-45 years old, intrauterine pregnancy, and intact fetal membrane. Exclusion criteria: unexplained vaginal bleeding; placenta previa; cervical cerclage; subjective induction of labor and abortion; antibiotic treatment within 4 weeks; sexual intercourse or use of vaginal medication within 3 days; mental or intellectual abnormalities or unable to answer related questions; incomplete questionnaire information; vulvar skin diseases, etc. The pregnant women were informed of the purpose of the study and all patients were included in the study after informed consent.