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In the years of conducting use-effectiveness studies in the various natural methods of family planning, there has been very little effort placed into the better understanding of the statistical measures upon which family planning systems are actually studied. There has been an emphasis to try to match up a natural method with a contraceptive method with regard to statistical protocols. And yet, one system, the contraceptive method, can be used in only one way, and therefore, its measurement for use can be accomplished only from that point of view. A natural method can be used to both achieve and avoid pregnancy, and most achievers are successful users, not failures. Thus, they need to be looked at separately and we have published a life table protocol that helps accomplish this.7 There are many reasons why they should be evaluated separately, but these are too long to go into at this time. However, if
somebody would like more information on this, I would be happy to provide it to them.
Thomas W. Hilgers, MD Department of Obstetrics and Gynecology, Creighton University School of Medicine, Omaha, NE
Pope Paul VI Institute for the Study of Human
Reproduction, Omaha, NE
References
Manhart MD, Duane M, Lind A, Sinai I, Golden-Tevald J. Fertility awareness-based methods of family planning: a review of effectiveness for avoiding pregnancy using SORT. Osteopath Fam Phys. 2013;5:2–8
Hatcher RA, Trussell J, Nelson AL, Cates W, Kowal D, Policar MS.
Contraceptive Technology. Ardent Media, Inc., 20th ed, 49
Hilgers TW, Stanford J. Creighton Model NaProEducation Technology for avoiding pregnancy: use effectiveness. J Reprod Med. 1998;43: 495–502
Hilgers TW. The objective classification of pregnancies. In: Hilgers TW, Hilgers SK, Prebil AM, Daly KD, eds. The Creighton Model FertilityCare™ System: A Standardized Case Management Approach to Teaching. Book II Advanced Teaching Skills. Omaha, NE: Pope Paul VI Institute Press; 2003
Hilgers TW, Daly KD, Prebil AM, Hilgers SK. The Creighton Model FertilityCare™ System: A Standardized Case Management Approach to Teaching. Book I. Omaha, NE: Pope Paul VI Institute Press; 2002 Hilgers TW, Daly KD, Prebil AM, Hilgers SK. The Creighton Model FertilityCare™ System: A Standardized Case Management Approach to Teaching. Book II. Omaha, NE: Pope Paul VI Institute Press; 2003
Hilgers TW. The Medical & Surgical Practice of NaProTechnology. Omaha, NE: Pope Paul VI Institute Press; 2004
Hilgers TW. The statistic of evaluation of natural methods of family planning. Int Rev Nat Fam Plan. 1984;8:226
Response to letter to the editor of osteopathic family physician from Dr Thomas Hilgers
We read with interest Dr Hilgers' comments on our paper. The purpose of the paper was to establish the parameters that would define a robust cohort study. These parameters allowed us to use SORT criteria to review the literature and identify the modern FABMs that had sufficient evidence to support their recommendation to couples who are seeking to avoid pregnancy. Dr Hilgers disagrees with our definition of typical use pregnancies, criticizes the criteria for not further elaborating on the means of pregnancy evaluation and standardized counseling used within the studies, and takes exception to the idea that more than one FABM may be useful in medical diagnosis.
We agree with Dr Hilgers that natural methods are unique as they can be used both to achieve and avoid pregnancy. In contrast, a contraceptive method is only used to avoid pregnancy, so if a pregnancy results, it is reasonable to conclude that it is a failure of the method. As Dr Hilgers, and our review, point out, this is not the case for natural methods; couples have the freedom to use the
method as they choose—either to avoid or to achieve a pregnancy—at any time. This complicates the definition of typical use.
We chose to use the definition of “typical use” to include the analysis of all pregnancies in all cycles of use. This makes the conservative assumption that the pregnancy is unintentional if not declared prospectively as intentional by the couple (one of our critical study parameters). In contrast, the Creighton Model FertilityCare System (CrMS) studies cited a different definition of typical use relying on couples' behavior during the fertile window. Although this approach is logical, all the other literature does not evaluate pregnancies in this way. We pointed this difference out in the review text and factually stated “typical use effective- ness cannot be defined as in other trials” for the CrMS trials. In developing the SORT criteria, we sought to set a robust standard yet not be so limiting as to exclude all but a few of the well-conducted studies. Although the precise approach to pregnancy evaluation can influence outcomes, we believe the combination of mechanisms to capture all pregnancies in all study participants, limiting intended pregnancies to the definition provided, and application of
the typical use analysis discussed earlier, gave sufficient strength to a study design. Similarly, in reviewing the various approaches to standardized counseling used in the FABM literature, we felt that use of a standardized method of instruction of the method being tested was critical. We reasoned that the quality of the standardization would be reflected in the pregnancy outcomes; less effective mechan- isms of teaching should result in higher typical use unintended pregnancy rates. CrMS professionals use a very standardized approach. Dr Hilgers argues that only the CrMS approach is viable. Yet many hundreds of thousands of couples have learned other FABMs following a different standardized curriculum and successfully used them to plan their families with a high degree of satisfaction.
Finally, Dr Hilgers takes exception to our assertion in Table 1 that more than a single FABM may be used to help with medical diagnosis. We created the table to give some guidance to physicians and couples that might be helpful in choosing a method most suited to their individual circumstances. Although the CrMS is among the most developed and published for medical diagnosis and
applications, other FABM have also been used by physicians to help identify women who might need further medical evaluation and treatment.1 More in-depth coverage of this aspect of natural methods is beyond the scope of this paper.
We hope that this conversation might prompt our colleagues to further investigate the modern FABMs as viable options for family planning and in some instances as an aide in addressing gynecological health problems. We encourage fellow primary care physicians to expand their knowledge, so they may provide current, accurate informa- tion to their patients.
Sincerely, Authors
Reference
Vigil P, Blackwell LF, Cortes ME. The importance of fertility awareness in the assessment of a woman's health; a review. Linacre Q. 2012;79 (4):426–450