Depo-Provera is given once every 3 months, or every 13 weeks. That schedule applies to the standard intramuscular shot. A lower-dose version designed for injection just under the skin follows a similar timeline of every 12 to 14 weeks. Missing that window can leave you unprotected, so understanding exactly how the timing works matters.
The Standard 13-Week Schedule
The intramuscular version of Depo-Provera is injected deep into muscle tissue, typically in the upper arm or buttock, by a healthcare provider. You need four shots per year, spaced 13 weeks apart. The subcutaneous version, which goes just beneath the skin of the abdomen or front of the thigh, works on a 12- to 14-week cycle. Both versions use the same active hormone and carry the same risks and benefits.
If you’re getting your first shot, timing it during the first few days of your period provides the fastest protection. When the injection is given outside that window, you’ll typically need to use a backup method like condoms for the first seven days.
What Happens If You’re Late
Life gets busy, and the CDC builds in a grace period. For the intramuscular shot, you can be up to 2 weeks late (15 weeks from your last injection) without needing backup contraception or a pregnancy test. That buffer exists because the hormone levels remain high enough to prevent ovulation during those extra two weeks.
The subcutaneous version has a tighter window. If more than 14 weeks pass between injections, pregnancy needs to be ruled out before the next dose. So while the intramuscular shot gives you a 15-week outer limit, the subcutaneous version caps out at 14 weeks. Setting a calendar reminder a week before your next shot is due can help you stay on track.
How Effective the Shot Is
When used perfectly, meaning you show up every 13 weeks without fail, Depo-Provera has a failure rate of just 0.2% in the first year. That means only about 2 in 1,000 women get pregnant. With typical use, which accounts for people who occasionally come in late or miss an appointment, that number rises to about 6%. The gap between those two numbers is almost entirely about staying on schedule.
The Two-Year Consideration
Depo-Provera carries an FDA boxed warning about bone density loss. Women who use the shot lose bone mineral density over time, and the loss increases the longer you stay on it. The FDA recommends against using it for longer than two years unless other birth control options aren’t a good fit for you.
This is especially relevant for adolescents and young adults, because those years are when bones are still building toward their peak strength. After stopping the shot, bone density does recover, but not completely. Studies tracking adults after discontinuation found only partial recovery at the hip and spine by 24 months. In adolescents, bone density at the hip hadn’t fully returned even five years after their last injection. If you’ve been on the shot for close to two years, it’s worth having a conversation about whether to continue or switch methods.
Fertility After Stopping
Unlike birth control pills or an IUD, Depo-Provera doesn’t wear off the moment you stop using it. The hormone lingers in your system, and ovulation can take several months to return. Most women begin ovulating again within 6 to 10 months after their last injection, though for some it can take longer. If you’re planning a pregnancy in the next year, factor in that delay when deciding whether to get your next shot.
This delayed return to fertility is one of the most common surprises for people coming off Depo-Provera. It doesn’t mean anything is wrong. The hormone simply takes time to clear, and your body’s natural cycle needs time to restart. Planning ahead by switching to a shorter-acting method a year or so before you want to conceive can help avoid frustration.