The Contraceptive Efficacy and Safety of an Intravaginal Acetic Acid Thermoreversible Gel on Chinese Women.

Inclusion Criteria: * 1\) Aged between 20 and 45 years old; * 2\) Regular menstrual cycles (cycle length 25-35 days, menstruation lasting up to 7 days); * 3\) Have a history of pregnancy with the current partner at least once; * 4\) Currently engaging in regular sexual activity and planning to do so in the next six months (at least once a week); * 5\) Have not used hormonal contraceptive methods in the past 3 months; * 6\) Normal menstrual cycles have resumed after the removal of an intrauterine device; * 7\) Normal menstrual cycles have resumed after a previous miscarriage; * 8\) Breastfeeding women with normal menstrual cycles resumed; * 9\) No apparent gynecological abnormalities confirmed through examination, and normal cervical cytology (Pap smear grade I according to the Bethesda system); * 10\) Reliance on the investigational drug as the sole contraceptive method during the study period; * 11\) Willing to participate in this study, adhere to required follow-up visits, and voluntarily sign the informed consent form. Exclusion Criteria: * 1\) Amenorrhoea for more than 1 month, suspected pregnancy; * 2\) Moderate to severe erosive changes in the cervix; * 3\) Vaginal cleanliness grade III or above; * 4\) Trichomonas, fungal vaginitis, and bacterial vaginosis, among other conditions, have not been cured; * 5\) Uterine prolapse of degree II or above and severe protrusion of the anterior and posterior vaginal walls; * 6\) Unexplained vaginal bleeding; * 7\) Genital tract deformities; * 8\) Malignant tumors of the genital tract; * 9\) Moderate or severe urinary incontinence; * 10\) Recurrent urinary tract infections; * 11\) History of allergy to acetic acid and/or nonoxinol.