Oh- if that’s what you’re interested in, my answer is a bit lengthier. My DH and I knew about NFP but also knew that I had irregular cycles and that getting pregnant for us would be difficult. We didn’t take any classes and instead tried to conceive starting when we got married. A year later, we started to take clomid, first unregulated, then we went to a traditional fertility clinic, got pregnant (no IVF or IUI, just medications and regular intercourse), and lost the baby. Our hearts were cleared of any thoughts of achieving pregnancy based on what we were told at the traditional fertility clinic as to our hopes of ever achieving a pregnancy.
DH and I started looking into adoption, and as we started the process, were told by no less than 15 people (all different sorts of people, some virtual strangers, one an on-line friend in Australia) that we should look up the Pope Paul VI institute. We did so, learned the Creighton model, met with the doctor there and for the first time, had actual hope that we could get pregnant. We’re still working on it, but I am so glad that we are using NFP now.
For me what interests me in the Creighton model is that it is natural, it is truly unitive, and that it helped identify several medical issues that I have which have now been treated. I formerly had really irregular cycles (2 periods each year, a period for four months, a period every other week, etc…) and now am on a nice 28-30 day cycle.