Objective: To identify predictors of fertility awareness-based method use. Design: Ongoing, prospective internet-based cohort study. Setting: Nurses living in the United States and Canada. Population: Women trying to become pregnant or contemplating pregnancy. Methods: Multivariable negative binomial regression. Main Outcome Measures: Fertility awareness-based methods. Results: Among the 23,418 women with pregnancy intention, 955 were trying to conceive and 2,282 were contemplating pregnancy. The ongoing duration of pregnancy attempt and gravidity were associated with the number of fertility awareness-based methods used among women actively trying to conceive. Compared to women who had been trying for two months or less, the number of methods was 29% (95% CI, 1.11—1.51), 45% (95% CI, 1.27—1.66) and 38% (95% CI, 1.21—1.58) higher for women who had been trying for 3-5 months, 6-12 months, or more than 1 year, respectively. Compared to nulligravid women, the number of fertility-awareness based methods was 17% (95% CI, 0.70—0.98) lower for women with a history of two or more pregnancies. Among women contemplating pregnancy, those who were married or in a domestic partnership used on average 39% (95% CI, 1.23—1.57) more fertility awareness-based methods than unpartnered women. Conclusion(s): Duration of ongoing pregnancy attempt and gravidity were the only significant predictors for number of fertility awareness-based method use among women trying to conceive, whereas partnership was the only significant predictor among women contemplating pregnancy.Funding: Supported by grants R24ES028521 and U01HL145386 from the National Institutes of Health. Keywords: pre-conception, pregnancy planning, fertility awareness-based methods.