 [ Symptoms ] is the depo shot 99 effective per shot or 99 effective while in use  depo has 99 effectiveness rate i was under the impression that with each depo shot i have a 1 chance of failure however my husband thought that the statistic really meant that while on depo the entirety of all shots over a period of time i have a 1 chance of failure meaning 1 in every 100 women get pregnant while on depo i have done research and the statistics say 3 in every 1000 women get pregnant while on depo  so which is it  99 effectiveness per shot or 99 effectiveness while in use [ Disease ] hi first you should google the side effects of depo shot second i do not think it would be very wise for a women not to have periods never would not be good for your body it needs this to flush it out your a women live with it like the rest do good luck