** Thanks for contacting HCM with your health concern 1. Depo provera is a hormone injection [progestin] which can prevent unplanned pregnancy and irregular bleeding is the most common side effect of the same and has to be taken every 3 months [12 weeks] and if one is late for injection one may require to take pregnancy test 2. pain abdomen,weight gain are also the mild side effect of the injection [for exhaustive list] you have to consult an OBGYN Doctor to further discuss the options PS. If periods/spotting become heavy or continuous for more than 14 days, make an appointment to speak with your doctor so they can determine whether these issues are normal and also it helps them to detect any possibly serious problems.