Can you become pregnant on the depo-provera shot?

Yes: The failure rate for Depo-Provera is about 1%.

Rarely happens: DepoProvera works by suppressing the release of pituitary gonadotropin hormones that normally keep menstrual cycles regular. Once the Depo's suppression is removed, the normal ovulatory cycle should resume (but it's not predictable exactly when). If a woman thinks she might be pregnant even though on Depo, a urine pregnancy test three weeks after having sex can tell if there's a pregnancy.