Is getting your period a sure sign you're not pregnant? could something else cause period like bleeding with cramps?

Yes and yes...: If your period came on time and was normal in length and amount of flow, it usually means you are not pregnant. There are situations that can mimic a period such as a very early miscarriage or bleeding with implantation but usually this bleeding is different than a normal period. If there is any question in your mind, you can do a home pregnancy test or see your doc for a blood test.

No, it is not: Some women will continue to have one or several menstrual periods, even though they are pregnant. Bleeding in early pregnancy always raises the concern of a threatened miscarriage.