Natural family planning (NFP) methods are not highly effective contraceptive options. The most important consequence of contraceptive failure is unintended pregnancy, which is costly to the individual and to society. Although there are some persons who for cultural and religious reasons prefer to use NFP, a majority of men and women value the assurance of using a birth control method that is reliable and convenient, because unintended pregnancy comes at a high personal cost. NFP is neither reliable nor convenient, and should be reserved for those with religious or cultural beliefs that preclude the use of other contraceptive methods.

In this issue of American Family Physician, Drs. Smoley and Robinson state that “because (NFP) methods do not require pharmaceutical or procedural intervention, they have no medical adverse effects.”¹ However, this statement does not acknowledge that unintended pregnancy is the ultimate adverse effect. One-half of all pregnancies in the United States are unintended, resulting in significant health care costs and morbidities.² Each year in the United States, unintended pregnancy results in an estimated $12 billion in health care costs: $103 million for pregnancy terminations, $251 million for fetal loss, $6 billion for births, and $5.8 billion for infant medical care.³ There are also social and emotional costs that cannot be calculated as a dollar amount.

Most of the reported data on the effectiveness of NFP is based on perfect use. The complexity and diligence required by many NFP methods make them unrealistic and untenable for many persons. With typical use, up to 25 percent of women using NFP will become pregnant within the first year,¹ which is higher than the rate of pregnancy for typical users of condoms (18 percent).⁴ As an example of the difference between perfect and typical use, withdrawal has an unintended pregnancy rate of 4 percent with perfect use, but a 22 percent rate with typical use.⁵ Although this is far lower than the pregnancy rate when no contraceptive method is used (85 percent), it is hard to argue that withdrawal is effective in comparison with most non-NFP options. Of the NFP methods, only lactational amenorrhea has been acknowledged as highly effective. However, this method is limited to women who are exclusively breastfeeding, are less than six months postpartum, and have amenorrhea.⁶

The consequences of unintended pregnancy on a person's health and well-being are important considerations for contraceptive counseling. Women who have medical conditions for which pregnancy would create an unacceptable health risk should be advised that NFP may not be appropriate for them. In most cases, methods with solid evidence and more effectiveness with typical use are preferred.⁷

When choosing a contraceptive method, couples must consider many factors with the guidance of their physician. These include the acceptability of the method, safety, potential adverse effects, accessibility, cost, and potential comorbid medical conditions that may influence their selection. Because contraceptive technology has advanced to the point that many safe, affordable, readily accessible, and highly effective options are available for persons with a variety of needs and comorbidities, NFP should be considered only as a second-line choice when more effective methods are not acceptable.