Menstrual periods return to normal once Depo-Provera leaves the system, which can take six to 18 months, according to the Family Planning Council. The amount of time it takes for ovulation and menstruation to return to normal seems unrelated to length of use, WebMD points out.
Depo-Provera takes a few months to leave the body completely because it is stored in fat cells, notes the Family Planning Council. The drug causes irregular periods and spotting in most users, and some experience heavier and longer periods or longer intervals between periods, according to Options for Sexual Health. Many women stop having periods, but this change is reversible.
Although ovulation and menstruation cycles remain affected for several months, women may still fall pregnant after discontinuing the medication. Conception can occur as early as three to four months after the last shot, but some women take up to two years to fall pregnant, according to WebMD.
The average interval between stopping Depo-Provera shots and pregnancy is nine to 10 months, according to Options for Sexual Health. After two years, pregnancy rates are on par with those of women who use other forms of birth control, such as birth control pills or intrauterine devices.