When can a woman have repeat progestogen-only injectables-depot medroxyprogesterone acetate or norethisterone enantate?

Studies evaluating time to pregnancy after last injection of DMPA or NET-EN reported extremely low pregnancy rates during the 2-week interval following the reinjection date; extremely low pregnancy rates for DMPA were also reported for 4 weeks following the reinjection date. Studies of return to ovulation after last injection of DMPA generally found that the earliest ovulation did not occur until several months after the last injection while studies of NET-EN reported ovulations around (or even before) the time for reinjection.