In the context of continuous cultural, social, and economic changes happening around the globe, the predictable patterns of the life course of the past observed over successive birth cohorts will not remain stable across generations. In this study, three reproductive role indicators—first sexual encounter, first marriage, and first birth–for three synthetic birth cohorts were used to identify and characterize the reproductive trajectories of youths. In our analysis, for the sake of comparison with global literature, we considered youths to be between ages 15 and 24. The analysis was conducted using data extracted from 2005, 2011, and 2016 Ethiopian Demographic Health Survey for Oromia National Regional State. Three synthetic birth cohorts of youths of birth years between 1975 and 1989 were constructed for the analysis. A sequence analysis based on dynamic hamming distance with partition around medoids technique was employed to extract the typologies of reproductive trajectories of youths. In addition, discrepancy analysis and a sequence regression tree analysis were employed to characterize the identified typologies of trajectories. Data management was done using STATA 14 and all analyses were carried out using R software. The study identified four different typologies of reproductive trajectories among the youth. The sex of respondents was the primary discriminating factor of the typologies of reproductive trajectories. The findings support the notion of changing norms in reproductive behavior among the less educated youth irrespective of sex. The discriminating power of education was stronger for female youth in urban areas than rural females. It implies that the postponement of reproductive role assumption was stronger among educated female youths residing in urban than their rural counterparts. Normative reproductive practices such as early marriage and adolescent fertility are still common practices that require efforts of communities and local government bodies to ameliorate these practices. Results of the study indicate that less educated youth should be targeted in programs that aim at improving youth empowerment (i.e., training and employment opportunities) as well as their sexual and reproductive health.