I am on my first month of Yaz birth control and my period came one week early. I am going to finish out the first pack (4 active and 4 inactive pills) as normal and then start my second pack next week. I've never had an early period while on the pill, so I'm not sure what precautions I should take in terms of having sex. When I'm done with the first month, do I still need to use a back up method of birth control?