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Ceiba logoCEIBA: Creighton Model Effectiveness, Intentions, and Behaviors Assessment

The Creighton Model FertilityCare System (CrM) is the most standardized and medically developed method of natural family planning in the United States. It is based on the observations of biomarkers of the menstrual cycles, particularly vaginal bleeding and cervical fluid. It can be used in all reproductive situations including regular, irregular, or absent menstrual cycles. The primary goal of the CEIBA study is to assess the effectiveness of the CrM to avoid pregnancy with newer statistical methods, and in the context of motivations, intentions, and behaviors of the participating couples during its use. The study is observational in nature and does not involve any blood tests or medications.

No Longer Enrolling

We have enrolled 312 couples in the study, and enrollment is complete. We are now finishing up collecting data and doing preliminary analyses. We will be posting results from the analysis of the study on this website over the next year, so be looking for them!

For further information about the study, you can email us at, and read our entry at