Fertility Awareness-Based Methods: Another Option for Family Planning

Stephen R. Pallone, MD; George R. Bergus, MD


J Am Board Fam Med. 2009;22(2):147-157. 

In This Article

Cervical Secretion Methods

Studies have found cervical secretion characteristics to be highly predictive of ovulation and can therefore be used to avoid pregnancy.[64,65] Studies conducted by the World Health Organization indicate that 93% of women, regardless of their education level, are capable of identifying and distinguishing fertile and infertile cervical secretions.[66]

Three main cervical secretion methods exist and are described below. All the methods involve noting the presence or absence of cervical secretions, usually recommended to be checked both at midday and early evening when women are less likely to have sex. Women are further asked to characterize the secretions as to color, texture, and stretch, the detail depending on the method of instruction. Fertile cervical secretions are clear, wet, slippery, stretching and changing in quality. They are often compared with egg whites. Infertile secretions are unchanging and generally dry, sticky, cloudy, and do not stretch. Menstruation is considered fertile because menses can mask the signs of cervical secretion, as can sexual fluids. Therefore, a day of abstinence after coitus occurring between menstruation and ovulation is required to interpret secretion signs. Hence, every other day between menstruation and the onset of the fertile phase is available for intercourse. One identifies peak fertility retrospectively when fertile secretions begin to return to a basic infertile pattern. It is safe to have intercourse without restrictions on the fourth day after peak fertility until the onset of the next menses. Any bleeding or cervical changes that interrupt the basic infertile pattern are potentially fertile.[50,51]

The Billings Ovulation Method (BOM) was the first described and allows women to describe secretions "in their own words" with a focus on changes in cervical characteristics. It has undergone refinement since studied in the United States.[5,50] In a study undertaken in India, pregnancy rates among perfect and all users of this method were 1.1% and 2% to 10.5%, respectively, at 12 months.[5,6] In the US study (1975 to 1977), method- and typical-use pregnancies were 1% and 16%, respectively.[25] The World Health Organization study of 1981 calculated typical-use pregnancies of 22.3%, with 15.4% caused by a conscious departure from method rules.[17] A randomized trial in China reported typical-use pregnancy with BOM as 0.5% when used to avoid pregnancy and had higher adherence than the copper intrauterine device to which it was compared. However, the data has not been published for peer review in English and the BOM Association reports that women unable to identify fertile cervical secretions were excluded.[67] Discontinuation rates were 0.5% and 24% at 12 months in China and India, respectively, and 44% at 2 years in the United States.[5,6,25]

A distinct method, the Creighton Model (CrM), also called NaProTechnology, is more standardized in the way secretions are characterized, using pictures and precise words to describe them.[8,9,51] The male partner is responsible for charting and interpreting the data, a step supporters believe encourages sharing responsibility for family planning and facilitates communication and relationship building. The effectiveness of the CrM has improved since its introduction in 1980, presumably because of improved methods of instruction.[8,9] CrM instructors must be certified in a year-long program accredited by the American Academy of Natural Family Planning and are asked not to prescribe other forms of birth control. Standardized patient instruction involves 8 one-hour sessions over the course of 1 year, 5 of them in the first 3 months.[51] CrM users are instructed that conscious departure from the method rules resulting in intercourse on method-predicted fertile days implies that they are no longer using the method for avoiding pregnancy but for achieving pregnancy. All pregnancies resulting from such actions are thus classified as achieving-related pregnancies without distinguishing between intended or unintended pregnancies. Although the argument of classifying pregnancies based on the "objective behavior of the patient" has merit, it is inconsistent with the majority of other family planning investigational methods, which would report some of these pregnancies as unintended or unplanned. CrM studies are "in vivo" and include women who are not trying to avoid pregnancy. Comparison of the typical use of CrM to other methods is therefore difficult, and reported data of overall pregnancies is probably an overestimate of unintended pregnancies. Method-related pregnancies, however, are comparably reported.[8,9]

The TDM is a simpler method that can be taught during a routine office visit. The woman is taught to identify cervical secretions of any type regardless of their characteristics. She then is instructed to ask herself, "Did I notice any cervical secretions today?" If the answer is no, she then asks, "Did I notice any cervical secretions yesterday?" If the answer is no, then intercourse is unlikely to result in pregnancy. If the answer to either of the 2 questions is "yes," then intercourse has a high probability of resulting in a pregnancy. The same preovulatory cervical secretion check rules described above apply. There are no restrictions on coitus when cervical secretions meet the 2-days rule after peak fertility and until the onset of the next menstruation.[10,68]

All cervical methods are theoretically compatible with cycles of any length and variable hormonal states. However, they have not been studied in depth because of the expense of following women with longer cycles and medical concerns with shorter cycles.[10,50,51]


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