Brown spotting before period. Why?!

Kelsey

I stopped taking birth control in November 2016. I wanted my body to have time to get back to "normal" before my husband and I started trying to conceive. The past 3-4 cycles, I have 6-7 days of brown spotting/blood before my actual period starts. What does this mean? Should I be concerned? We are planning to start trying to conceive asap.