NFP can be used only by women withregular cycles.
NFP does not depend on a woman having regular menstrual cycles. NFP treats each woman and each cycle as unique. These methods rely on daily observations of the woman's signs of fertility.
NFP works with menstrual cycles of any length and any degree of irregularity. NFP can be used during breastfeeding, just before menopause, and in other special circumstances. NFP allows a woman to understand the physical signals her body gives her to tell her when she is most likely to become pregnant (around the time of ovulation). Once the woman understands this information, she and her husband can use the information according to their family planning intentions (i.e., to either achieve or postpone pregnancy).
Instruction in NFP provides women with information about their bodies that is specific and observable. The natural methods can be used throughout a woman's reproductive life. These methods teach couples to monitor current, daily fertility signs of the woman's menstrual cycle. When special circumstances occur, (e.g., stress, illness, breastfeeding, post-miscarriage, perimenopause, etc.), NFP instructors can provide additional guidance in interpreting signs of fertility.