The menstrual cycle is the time from the first day of menstruation until the arrival of the next menstrual period. WHO 2018 states that 80% of women in the world experience irregular menstruation. According to Basic Health Research Data (Kemenkes, 2018) where as many as 11.7% of adolescents in Indonesia experience irregular menstruation. This study aims to determine physical activity, stress levels and other factors during the Covid-19 pandemic with menstrual cycles in final year students S1 Regular FKM UI in 2022. This study is a quantitative study with a cross-sectional study design. Data collection was done by distributing online questionnaires using Google Forms. The independent variables used in this study were physical activity, stress levels, lecture stressors, age at menarche, diet, deviant eating behavior, sleep quality, and exposure to cigarette smoke. The results showed that (60.4%) of female students experienced irregular menstrual cycles. The factors that affect the menstrual cycle in final year undergraduate students of FKM UI Regular in 2022 are stress levels and diet as confounding variables. Diet is the most dominant factor affecting the menstrual cycle. It is recommended that female students pay more attention to diet because diet is the dominant factor that affects the menstrual cycle.