to the editor: This article did not discuss other effective family planning choices for couples who do not desire pregnancy. All of the hormonal contraceptives mentioned in the article are not without considerable risk of adverse effects, in addition to the increased risks posed by underlying comorbidities.

Physicians should be knowledgeable about nonpharmacologic methods of birth regulation, including fertility awareness-based methods, which involve women observing their own biomarkers of fertility and infertility through each menstrual cycle. My clinical experience with appropriately selected couples using the Creighton Model Fertility Care System to avoid pregnancy has been excellent. A meta-analysis of five studies of nearly 2,000 couples using the Creighton method¹ and a more recent review² found pregnancy rates of 0.5 percent with perfect use and 17.1 percent with typical use after 12 months. These figures are at least comparable to those of hormonal contraceptives.

to the editor: In this article, the authors present hormonal contraceptive options for family physicians to recommend to women with specific chronic medical conditions. The omission of any effective natural methods of fertility regulation perpetuates a general gap of knowledge among physicians unless they pursue specialized studies in this field.

The utility and wide applicability of a natural method of fertility regulation for purposes of avoiding pregnancy was established by the multicenter trial of the World Health Organization (WHO) in the 1980s. The WHO defines natural family planning (NFP) as “methods for planning and preventing pregnancy by observation of the naturally occurring signs and symptoms of the fertile and infertile phases of the menstrual cycle, with the avoidance of intercourse during the fertile phase if pregnancy is to be avoided.”¹

Counseling in natural methods of fertility regulation is currently being provided by a growing number of trained physicians, nurse practitioners, and allied health professionals. In the United States, methods include the Billings Ovulation Method, the Creighton Model Fertility Care System, the symptothermal methods, and the Marquette Method. These family planning methods should not be confused with calendar rhythm method and are not dependent on the regularity of a woman's cycle.

Population-based surveys have shown a significant interest in NFP—approximately 25 percent of women and 40 percent of men are interested in using NFP to avoid pregnancy, and 33 percent of women are interested in using NFP to conceive. This interest is not associated with religion, education, age, or income level.^2,3

Natural methods have been evaluated for their use effectiveness to avoid pregnancy and have been found to be highly reliable.⁴ Data were presented to the U.S. Department of Health and Human Services when the International Classification of Diseases, 9th revision, clinical modification (ICD-9-CM), was updated to include “counseling and instruction in natural family planning to avoid pregnancy” (V25.04), and “procreative counseling and advice using natural family planning” (V26.41).⁵ An overview presentation titled “Natural Methods of Family Planning” is available at http://www.cdc.gov/nchs/data/icd9/att4_NFP_mar06.pdf.

Recognizing that many hormone-based contraceptives and devices have mechanisms of action potentially interrupting a pregnancy in embryonic development,⁶ a growing number of family physicians have been pursuing training in natural methods of fertility regulation. Women who learn natural methods actively track their cycles, gaining practical day-to-day knowledge of their times of fertility and infertility, and the ability to recognize gynecologic abnormalities earlier.

Although hormonal contraceptives carry a known burden of risk, natural methods are completely free of medical adverse effects. Unfortunately, without training or practical exposure to their successful use, most physicians are ill-equipped to recommend natural methods.

We invite clinicians to develop confidence and competence in recommending a non-contraceptive family planning system by attending an annual meeting of the American Academy of FertilityCare Professionals (http://www.aafcp.org) or by contacting a local NFP center through FertilityCare Centers of America (http://www.fertilitycare.org); Billings Ovulation Method Association-USA (http://www.boma-usa.org); the Couple to Couple League for Natural Family Planning (http://www.ccli.org); or the Marquette Model of Natural Family Planning. (http://nfp.marquette.edu).

to the editor: In this article, the authors recommend progestin-only methods of contraception for women with a history of atherosclerotic arterial disease, venous thromboembolism, or other contraindications to the estrogens found in combination oral contraceptives. They discuss the use of depot medroxyprogesterone acetate (Depo-Provera), a long-acting injectable progestin; Implanon, a subdermally implanted singlerod device that releases a progestin; and Mirena, a levonorgestrel-containing intrauterine contraceptive system. The authors omitted any discussion of progestin-only oral contraceptives (i.e., the “mini-pill”). This contraceptive is known as the minipill because the dose of norethindrone is substantially lower than the progestin dose found in any combination oral contraceptive. Many physicians consider the mini-pill the most reasonable first choice for women considering progestin-only contraception because it can be quickly discontinued if the patient experiences intolerable adverse effects. If the mini-pill is well-tolerated, women can consider a long-acting delivery system. Norethindrone is the only progestinonly oral contraceptive approved in the United States. It is available at a dosage of 0.35 mg per day, in 28-day packs, to be taken continuously with no pill-free interval.