I can't believe people STILL believe that women's cycles are all 28 days. I'm a perfectly healthy woman with a cycle of 32 days. I have a friend who's cycle is 25 days. We're all different!If you want to REALLY learn about your fertility and menstrual cycles, read a freakin' book. I recommend "Taking Charge of Your Fertility." It's well written and teaches women how to really know their cycles and stop relying on junk like this and doctor's who still use a 28 day cycle chart to determine conception dates and due dates.It's 2010 people. Learn about your bodies and stop being so gullible!