Getting pregnant on the Depo-Provera shot is uncommon but not impossible, and the reassuring news is that accidental exposure to the medication in early pregnancy does not appear to cause significant harm to the baby. About 4 to 6 out of every 100 people using the shot will become pregnant in a given year, mostly due to late or missed injections. If it happens to you, the biggest challenges are recognizing the pregnancy early and ruling out a few specific complications.
How Pregnancy Happens on the Shot
With perfect use, the shot is 99% effective. But “perfect use” means getting your injection exactly on schedule every 13 weeks, and real life doesn’t always cooperate. When people are late for their appointment or miss a shot entirely, effectiveness drops to roughly 94 to 96%. That gap is where most unintended pregnancies occur.
The shot works by suppressing ovulation and thickening cervical mucus. Once the hormone level from your last injection starts to drop, ovulation can resume before you realize protection has lapsed. This is especially likely if your next shot is more than a week overdue.
Why You Might Not Realize You’re Pregnant
One of the trickiest things about getting pregnant on the shot is that the medication itself mimics many early pregnancy symptoms. Most people on the shot stop getting regular periods altogether, so a missed period won’t tip you off. Weight changes, bloating, breast tenderness, nausea, and fatigue are all common side effects of the shot on its own.
This overlap means pregnancies on the shot are often discovered later than pregnancies in people using other methods. If you’ve been late on your injection and notice symptoms feeling more intense than usual, or if something just feels different, a home pregnancy test is a reliable way to check. The shot does not interfere with pregnancy test accuracy.
Risks to the Baby
The FDA’s prescribing information states directly that there appears to be “little or no increased risk of birth defects” in women who were inadvertently exposed to the shot in early pregnancy. Children who were exposed in the womb and followed through adolescence showed no adverse effects on their physical, intellectual, sexual, or social development. This is one of the most reassuring findings in the research, and it comes from long-term follow-up data.
The one area with less certainty is birth weight. Two studies found a possible link between the shot and low birth weight (babies born under about 5 pounds, 8 ounces), while a third study did not find that connection. Research on whether the shot affects preterm delivery risk simply hasn’t been done yet, so there’s no clear answer on that front. These gaps in the data are worth discussing with a provider, but they don’t point to a definitive problem.
Miscarriage and Ectopic Pregnancy
A large prospective study published in BMJ Medicine found that people who most recently used injectable contraceptives had a slightly higher rate of miscarriage compared to those using barrier methods like condoms. The increase was about 44% in relative terms, but the researchers described the finding as “tentative” because the numbers were small and the statistical confidence was borderline. It’s a signal worth noting, not a confirmed risk.
Ectopic pregnancy, where a fertilized egg implants outside the uterus (usually in a fallopian tube), is another possibility flagged in the FDA labeling. No specific rate is given for shot users, but the warning exists because the shot is better at preventing normal uterine pregnancies than ectopic ones. This means that if you do conceive on the shot, the relative proportion of ectopic pregnancies is higher than it would be in the general population. Severe abdominal pain, dizziness, or shoulder pain after a positive pregnancy test are signs that need immediate medical attention.
What to Do If You Suspect Pregnancy
Take a home pregnancy test as soon as you have any suspicion. If you’ve been getting your shots on time every 13 weeks, pregnancy is very unlikely, but testing is simple and definitive. A positive result means you should get an early ultrasound to confirm the pregnancy is in the uterus and to establish how far along you are, since missed periods can’t help you date the pregnancy.
You’ll stop receiving further injections, but the hormone already in your system from the last shot will gradually clear on its own. There’s no antidote needed and no procedure to “reverse” the shot. The medication simply wears off over the following weeks. Based on the long-term follow-up data, the residual hormone circulating during early pregnancy does not appear to harm fetal development.
Fertility After Stopping the Shot
If you discover you’re pregnant on the shot, fertility clearly wasn’t an issue. But if you decide not to continue the pregnancy and want to conceive later, or if you’re stopping the shot specifically to try getting pregnant, it’s helpful to know that the return of fertility is slower with this method than with pills or IUDs. On average, it takes about 10 months after the last injection for ovulation to return reliably, though some people ovulate much sooner and others take up to 18 months. This delay is the drug clearing your system, not a sign of lasting damage to your fertility.