The purpose of this study is to understand how immunity changes in the vagina over the course of the menstrual cycle. The study consists of 3 visits over the course of approximately a month. Visit procedures include vaginal swab collection, STI screening, blood draws, and vaginal and cervical biopsies. You will also be asked to collect daily vaginal swabs and conduct a daily ovulation test for a period of about 2 weeks.

Eligibility Criteria:

• 18 years of age or older
• Assigned female at birth
• Pre-menopausal with fairly regular menstrual cycles

Conditions which would prevent a volunteer from participating in this study:

• Pregnant or planning to become pregnant during the study
• Recent use of a hormonal contraception, IUD, or IUS

Compensation:

Participants who complete all study visits and procedures will be compensated.