This post is a synopsis of the research presented in the article published in Contraception by Sinai and Arevalo. It is a post in a series entitled Featured Research where we go back and break down some of the foundational research about different fertility awareness based methods (FABMs). We hope after reading this post you are inspired to check out the original research article for more specifics about the study! A longer list of studies is also available here.


Photo Credit: https://standarddaysmethod.org/

Photo Credit: https://standarddaysmethod.org/

by Amylynn Smith

The Standard Days Method is a fertility awareness based method (FABM) developed by the Institute for Reproductive Health at Georgetown University (IRH) that can be used very effectively by women who have regular cycles consistently ranging from 26-32 days in length. “Consistently” is defined as having no more than 2 cycles outside of this cycle length range within one year. The IRH identified a set fertile window for all cycles: day 8 to cycle day 19.

In the initial efficacy study conducted by the IRH that determined this fertile window, 478 women ages 18-39 were followed over the course of one calendar year. These women had to pass through strict screening protocols and had monthly interviews with providers to monitor for cycle regularity. The correct-use pregnancy rate of 4.8 at one year and a typical-use pregnancy rate of 12. In this paper, the authors primarily seek to answer if the screening and monitoring protocols used by the IRH were necessary in order to achieve the reported level of effectiveness [1].

Why does it matter if the protocols are necessary?

Photo credit: https://www.psi.org/program/standard-days-method/

Photo credit: https://www.psi.org/program/standard-days-method/

Well, as the authors point out in this study, if the protocols that allow a woman to enter the study were too rigid, the method might be excluding women that could benefit from learning and using this FABM as a means of family planning. The IRH study was compared to another study conducted by the World Health Organization (WHO) looking at the efficacy of Ovulation Methods. The screening protocol used by the WHO admitted women to the study if they recalled having cycles over the last 6 months ranging from 23 to 35 days in length, and they chose not to monitor women for cycle length over the course of the study. To find out just how necessary screening potential female users is in addition to monitoring their cycle length to check for regularity, the authors chose to look at data collected by the WHO data through the lens of the IRH study screening and monitoring standards [2].

Monitoring users improves method efficacy

This comparative research study found that the screening protocol is most effective for women with cycles ranging from 26-32 days in length. However, It is also important to note, as the authors did, that no screening process can predict or guarantee that a woman will not have a cycle that is shorter or longer than the defined range over the course of her reproductive life. A suggestion is made to possibly restrict potential candidates for the method to those women who have only ever had one cycle out of the defined range in order to increase efficacy, as opposed to having up to two cycles out of 26-32 day range. The authors point out that this more strict protocol might require more front-end time and energy on the part of the provider and potential user to gather cycle history through charting and tracking cycle length.The monitoring of users by providers proves to lessen the likelihood that women with irregular cycles (outside of the 26-32 day range) would continue to use the method and therefore improve the method efficacy.

In conclusion, using an algorithm that is easy to remember and implement, the authors found the screening and monitoring protocols used by the IRH offer the best balance between providing a method that is highly effective and as inclusive as possible.

For more information, please read the full length article. Patients interested in learning more about this method should download a Standard Days patient information sheet (available in both English and Spanish) or look for more resources at the IRH.


Amylynn has been teaching the Creighton Model FertilityCare System for three and a half years to women in various stages of their reproductive life. She currently lives and works in Northwest Arkansas with her husband Joey.

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