The pill can make your periods lighter because less tissue is formed. My first period on the pill was light and lasted about 3-4 days, the 2nd month it was a little heavier, but still only lasted about 3 days. This month it is pretty light and I'm on day 2. It's normal for it to be lighter... It should say that in the info. that came with your pill. What pill are you taking? I am on Estrostep fe but switching to Levlite.