How Does the Birth Control Implant Work?

You’re probably well aware of the pill and how it works—but long-acting reversible contraceptives (LARCs), including the birth control implant (a.k.a. Nexplanon), don’t require a daily check on your to-do list.

There’s a growing interest in the etonogestrel birth control implant, and its set-it-and-forget-it nature likely plays a role in that. Once the tiny rod is placed in your arm, you don’t have to think about your birth control for years. Couple that with the fact that it’s highly effective at preventing pregnancy, and it’s an attractive contraception option, especially as the right to abortion and other forms of critical reproductive care are threatened in many states across the country.

So, how does the birth control implant work? Here’s what you should know if you’re looking to switch to a LARC and want to explore your options. 

How does the birth control implant work?

LARCs, which include the birth control plant and intrauterine devices (IUDs), are the most effective reversible contraceptive methods, according to the American College of Obstetricians and Gynecology (ACOG). LARC methods have a high success rate of preventing pregnancy while they are in place, but they shouldn’t directly impact your return to fertility; once the implant is removed, for example, you can get pregnant quickly if you don’t have other factors affecting your fertility, Christine Greves, MD, an ob-gyn at the Winnie Palmer Hospital for Women and Babies in Orlando, tells SELF. 

The birth control implant is pretty tiny—it’s just under 2 inches long and is about the size of a matchstick. “Nexplanon is a little rod of a synthetic progesterone [progestin] that goes right under the skin,” Mary Jane Minkin, MD, a clinical professor of obstetrics and gynecology and reproductive sciences at Yale School of Medicine, tells SELF. The implant is inserted into your non-dominant upper arm, where it can stay for up to three years to five years, per the ACOG.¹ (Don’t worry, your health care provider should numb the area, so you won’t feel any discomfort during this process.) 

The way it works is pretty cool: “The implant sends out [progestin] into the bloodstream, which gets to the ovaries to help suppress ovulation,” Dr. Minkin explains. “Also, [progestin] helps keep cervical mucus hostile to sperm—so it helps keep sperm from getting up into the uterus.”

Like any form of birth control, the contraceptive implant can come with potential side effects like spotting between periods, longer or shorter bleeding during your period, a heavier or lighter flow, varied amounts of time between periods, or no period at all, according to Planned Parenthood. Other possible side effects include the usual: headaches, breast soreness, and nausea, among others. “As long as you’re okay with the possibility of irregular bleeding…it’s a phenomenal form of birth control,” Dr. Greves says. 

How effective is the birth control implant at preventing pregnancy?

In general, “the implant is a good option for individuals who know they want to delay pregnancy for several years and do not want the hassle of taking a pill every day,” Alexa M. Sassin, MD, an assistant professor of obstetrics and gynecology at Baylor College of Medicine in Houston, tells SELF.