Aim: Simplified contraceptive method-efficacy and/or typical-use effectiveness rates are commonly used for direct comparison of the various contraceptive methods. Use of such effectiveness rates in this manner is, however, problematic in relation to the fertility awareness methods (FAMs). The aim of this review is to critically examine current international representation of contraceptive effectiveness for the various FAMs in clinical use. This review also details important issues when appraising and interpreting studies on FAMs used for avoiding pregnancy.
Methods: Current international literature regarding contraceptive effectiveness of FAMs was surveyed and appraised. This included World Health Organization and Centers for Disease Control (USA) resources, key clinical studies and recent systematic reviews. Chinese literature was also searched, since these data have not been reported in the English literature.
Results: Reliance on certain historical studies has led to the misrepresentation of contraceptive effectiveness of FAMs by perpetuation of inaccurate figures in clinical guidelines, the international literature and the public domain. Interpretation of published study results for FAMs is difficult due to variability in study methodology and other clinical trial quality issues. Recent systematic analyses have noted the considerable issues with study designs and limitations. Several non-English published studies using the Billings Ovulation Method have demonstrated that a broader review of the literature is required to better capture the data potentially available.
Conclusion: A deeper understanding by clinicians and the public of the applicability of contraceptive effectiveness rates of the various FAMs is needed, instead of reliance on the inaccurate conglomerate figures that are widely presented.
Keywords: contraceptive methods; fertility control; medical education; natural family planning methods; natural fertility.
© 2020 Japan Society of Obstetrics and Gynecology.