After gel administration, PK measures will be taken at Hours 1, 2, 4, 6, 8, and 12; maternal blood tenofovir level measurement and a review of adverse events will also occur at these times. A 24-hour evaluation will occur between Hours 22 and 26. At this evaluation, a targeted physical exam, a review of adverse events, and tenofovir level measurement will occur. Each participant will be contacted between Days 10 and 18 to collect data on any adverse events they experience. In addition, an unscheduled visit may be necessary if an unresolved adverse event occurs on or after the 24-hour evaluation. If an unscheduled visit is required, the participant will undergo a targeted physical exam, medical and medication history assessment, blood and urine collection, a pelvic exam, and tenofovir level measurement.