I know someone who used to do this method and at first it worked great for her. She had two kids and then after that no more kids. Like someone said above, I don't know if it's cause they weren't as strict in abiding by the rules or what, but after she had their third child, it all went downhill after that. This maybe just be an extreme cause (they now have six kids) but I personally don't know if I have the discipline to abide by the rules ALL the time. I guess it could be done if you were very mindful. Good luck!