Natural family planning: an update.

Natural Family Planning (NFP) is defined by the World Health Organization (WHO) as "methods for planning or avoiding pregnancies by observation of the natural signs and symptoms of the fertile and infertile phase of the menstrual cycle. It is implicit in the definition of natural family planning, when used to avoid conception that drugs, devices and surgical procedures are not used, there is abstinence from sexual intercourse during the fertile phase of the menstrual cycle, and the act of intercourse, when it occurs, is complete."(1) The fertile period may be determined by using Rhythm, a calculation based on previous cycles, basal body temperature (BBT) charting alone, mucus secretion alone (Billings or Ovulation method), or symptothermal charting (Serena method), which includes observation of both mucus and BBT. The effectiveness of each method is discussed, and the social and psychological profile of couples who use NFP is reviewed. Nfp methods can be used not only to avoid pregnancy, but also to achieve pregnancy and thus are particularly useful in investigating and treating infertility. The function of the Family Life Clinic at St. Michael's Hospital in Toronto is described.