Eh, I don't know. I think everyone is better off reading TCOYF, using free charting, and buying some cheap OPKs. I find the idea that they will help you chart for 3 months, and you will be pregnant or else understand why you are having a hard time to be kind of silly. Lots of people time sex perfectly and don't get pregnant in 3 months. IMO, it just seems like a cutesy way to get people to buy things that they could get much cheaper on their own.