- Book: Fertility, Cycles and Nutrition by Marilyn Shannon
- Book: The Art of Natural Family Planning (Symptothermal)
- California Association of NFP
- Couple to Couple League (To search for a Symptothermal Method Teaching Couple in your area, click here)
- Creighton Model
- Family of the Americas Foundation (Ovulation Method)
- NFP and More
- NFP Resource Manual (PDF. from the Archdiocese of Galveston-Houston)
- One More Soul (Has directory of NFP Teachers, and NFP-friendly doctors in many states)
- Pope Paul VI Institute
Basicallly, what NFP allows people to do is track the woman's cycle, looking for signs of fertility, and then act accordingly. These signs usually include basal body temperature and/or cervical mucous. It requires that both spouses be aware and respectful of the woman's fertility.
Any one of the available methods for tracking female fertility can allow couples to maximize (or minimize if they wish to space their children) the potential of their efforts to conceive.
While NFP is often touted as a Catholic thing, there are many non-Catholics who choose to use it. In addition to the many religious and moral reasons for using NFP, there are other practical concerns. Some use it because they find it is beneficial for their marriages. Others choose it because of medical concerns or even for the sake of the environment (you'd be surprised at where those hormones go). Couples who are interested in natural and organic living may find NFP particularly appealing, because it does not involve the ingestion of any synthetic hormones, or the use of man-made barrier methods.
On a side note, I personally find it to be a handy tool for me as I monitor my reproductive and general health. It has been interesting to see the not-immediately-obvious effects that stress, illness, weight, and diet can have on my body. (Stress, for instance, sends my basal body temp on a wild roller-coaster ride.) Closely observing and charting my cycle has allowed me to spot early signs that something may be negatively affecting my health, and this has allowed me to take care of problems before they get out of hand.