Background: Women's fear from childbirth has been associated with increased medical interventions and traumatized birth experience. Although antenatal education is a crucial factor to empower and prepare women for their birth journey, it is not clear how Iranian childbirth classes can influence women's fear and prepare them positively towards childbirth. This research is designed to evaluate childbirth preparation classes and their impact on women's perception on their childbirth experiences. Methods/design: This mixed method study with the parallel convergent design has two phases. The first phase will be a quantitative cohort study with 204 primiparous pregnant women at the gestational age of 35-37 weeks. The participants will be divided into three groups based on the number of their attendance into the childbirth preparation classes: A) regular participation (4 to 8 sessions), b) irregular participation (1 to 3 sessions), and c) no-participation. Participant will be followed-up to 1 month after birth. Antenatal data will be collected by using a demographic survey questionnaire, the Wijma Delivery Expectancy/Experience Questionnaire (W-DEQ, version A), the Van den Bergh Pregnancy-Related Anxiety Questionnaire, the Satisfaction with Childbirth Preparation Classes Questionnaire, the Edinburgh Postpartum Depression Scale (EPDS) and Knowledge regarding pregnancy and childbirth Questionnaire. Postnatal data will be collected by using an Obstetric and Labor Characteristics Questionnaire, EPDS, and Childbirth experience questionnaire (CEQ). The quantitative data will be analyzed using one-way ANOVA and the multivariate linear regression. The second phase of the study will be a qualitative study that will explore the women's perceptions on the impact of participation in childbirth preparation classes on their childbirth experience. The sampling in this phase will be purposeful and the participants will be studied individually by using in-depth, semi-structured interviews. The qualitative data will be analyzed through content analysis with conventional approach. Discussion: Assessing the impact of childbirth preparation classes on women's childbirth experience in Iran will lead to developing recommendations about the content and quality of the childbirth classes that can improve women's' preparation towards positive childbirth.