Very light af while ttc?

CeraBeth
I was just wondering if the flow of your af can change while ttc? I'm used to 7-8 days usuly very heavy first 3 and last 2 light, for the past 3 months it's been only 5-6 days and very light to only light medium flow, low enough to be only using half the tampons I usually do. Just wondering why this is?