How protected will i be from pregnancy 1 month after my first depo-provera injection if it was received not on period? percent of effectiveness?

99% effective: If given properly, Depo Provera (medroxyprogesterone) is 99% effective in preventing pregnancy. Birth control begins immediately after the first shot if given within the first five days of your menstrual period. If it was given later than the first 5 days of your menstrual cycle, your chance of pregnancy is still low, less than 15%. In this case, after the first 4 weeks, the effectiveness goes back up to 99%.