Does your menstrual cycle affect a blood count?

Your blood count can be effected by your period especially if you don't eat much iron and have long periods or more than one period a month. Add these with heavy bleeding and it can definitely effect it. It won't make much of a difference when the blood test is preformed. Your Hemoglobin and hemomatacrit will be a tiny bit lower if you've been on your period for a few days and then it gets checked.