This research is about understanding how different birth control methods might change the immune system and affect the risk of getting HIV. The study will look at women who are starting new hormonal contraceptives (birth control that uses hormones to prevent pregnancy) like DMPA (a shot), an Eng-Implant (a small rod put in the arm), or a Lng-IUD (a device placed in the uterus). The study will last up to 4 months. Scientists want to see if these methods change the body's defense system in ways that could affect how the body responds to infections like HIV. They will focus on how these changes happen in the body and the vagina, which is the birth canal.

• Study lasts up to 4 months with several visits.
• Participants must agree to not have vaginal intercourse or use certain products for 1 day before visits.
• Possible risks include immune changes that might affect infection chances.