To summarize best available prospective data on typical and perfect use effectiveness of fertility awareness–based methods for avoiding pregnancy.
We conducted a systematic review of studies published in English, Spanish, French, or German by June 2017 in MEDLINE, EMBASE, CINAHL, Web of Science, and ClinicalTrials.gov.
We reviewed 8,755 unique citations and included 53 studies that contained 50 or greater women using a specific fertility awareness–based method to avoid pregnancy, calculated life table pregnancy probabilities or Pearl rates, and prospectively measured pregnancy intentions and outcomes. We systematically evaluated study quality.
Of 53 included studies, we ranked 0 high quality, 21 moderate quality, and 32 low quality for our question of interest. Among moderate-quality studies, first-year typical use pregnancy rates or probabilities per 100 woman-years varied widely: 11.2–14.1 for the Standard Days Method, 13.7 for the TwoDay Method, 10.5–33.6 for the Billings Ovulation Method, 4–18.5 for the Marquette Mucus-only Method, 9.0–9.8 for basal body temperature methods, 13.2 for single-check symptothermal methods, 11.2–33.0 for Thyma double-check symptothermal methods, 1.8 for Sensiplan, 25.6 for Persona, 2–6.8 for the Marquette Monitor-only Method, and 6–7 for the Marquette Monitor and Mucus Method. First-year perfect use pregnancy rates or probabilities among moderate-quality studies were 4.8 for the Standard Days Method, 3.5 for the TwoDay Method, 1.1–3.4 for the Billings Ovulation Method, 2.7 for the Marquette Mucus Method, 0.4 for Sensiplan, 12.1 for Persona, and 0 for the Marquette Monitor.
Studies on the effectiveness of each fertility awareness–based method are few and of low to moderate quality. Pregnancy rates or probabilities varied widely across different fertility awareness–based methods (and in some cases, within method types), even after excluding low-quality studies. Variability across populations studied precludes comparisons across methods.
Prospective studies evaluating the effectiveness of specific fertility awareness–based methods to avoid pregnancy are of low to moderate quality; effectiveness estimates vary between and among methods.
Department of Obstetrics and Gynecology, University of North Carolina, Chapel Hill, North Carolina; Reply OB/Gyn & Fertility, Cary, North Carolina; the Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; the Guttmacher Institute, New York, New York; the Department of Epidemiology and Prevention, Wake Forest University School of Medicine, Winston-Salem, North Carolina; GreeneWorks, Washington, DC; and the Department of Family and Preventive Medicine, University of Utah, Salt Lake City, Utah.
Corresponding author: Rachel Peragallo Urrutia, MD, MS, Department of Obstetrics and Gynecology, University of North Carolina, CB#7570, Chapel Hill, NC 27599-7570; email: firstname.lastname@example.org.
Funding for the review was provided through a USAID contract. KNDR Healthcare, LLC provided in-kind donation (EK effort). KNDR had no role in the design of the project or review of the data or manuscript. USAID provided funding starting after the design of the project, the literature search, the abstract review, and the full-text review. They had no role in design of the project or data analysis plan. USAID read the manuscript before publication and provided comments that the authors were not obligated to incorporate.
Presented at the North American Forum on Family Planning, October 14–16, 2017, Atlanta, Georgia; the National Title X Reproductive Health Conference, July 15–18, 2018, Kansas City, Missouri; and the Annual Scientific Assembly Meeting of the International Institute of Restorative Reproductive Medicine, July 25, 2018, Ontario, California.
Chelsea B. Polis is affiliated with the Guttmacher Institute. Her affiliation is included for informational purposes only; this work was not conducted under the auspices of the Guttmacher Institute. The views expressed herein are those of the authors and do not necessarily reflect the views of the Guttmacher Institute.
The authors thank Ammu Vijay and Nancy DeMaria for their help during the abstract and full-text screening portions of the study; Jennifer Walker, MLS, for her assistance with developing and conducting the literature search; and Eugene Urrutia, PhD, for his help with preparation of Figures 2 and 3.
Each author has indicated that he or she has met the journal's requirements for authorship.
Financial Disclosure Dr. Peragallo Urrutia's salary to the University of North Carolina is paid in part by KNDR Healthcare, LLC, for her work at Reply Ob/Gyn & Fertility. KNDR's mission is to promote fertility awareness–based methods of family planning. The other authors did not report any potential conflicts of interest.