Hi,
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Pregnancy on Medroxyprogesterone is rare. It inhibits pregnancy in high doses. If the medication was given to you to induce withdrawal bleeding, then the sexual intercourse while being on treatment may not result in pregnancy. For what purpose were you prescribed these tablets?
However, the chances cannot be excluded completely due to uncertainty of your ovulation time. So discuss with your gynecologist about the unprotected intercourse while being on it.
Take care.