What are the chances of depo-provera provera (medroxyprogesterone) not preventing pregnancy? why? im on the depo-provera started july 2013 never spotted until april 2014 it was very light

Most likely: If you get your injections when they are due every time, the chance of getting pregnant on the intramuscular Depo Provera (medroxyprogesterone) is .7%. Its higher if you are sometimes late for your shot. Weird spotting on Depo Provera (medroxyprogesterone) is an annoying but common side-effect. It doesn't mean you are pregnant or even at risk to get pregnant. Studies show that bleeding is from a very paper-thin, fragile uterine lining.