Objective: To determine the psychological factors associated with antenatal depressive symptoms and to assess whether psychological flexibility moderates the relationship between negative anticipation and fear of childbirth and depressive symptoms during pregnancy. Design: Cross-sectional analysis based on baseline data from the Flexi-PREP longitudinal study. Setting and Population: A cohort of 395 pregnant women recruited from three French maternity hospitals during the third trimester of pregnancy. Methods: Participants completed an online survey assessing negative anticipation and fear of childbirth (W-DEQ-A), psychological flexibility (AAQ-II), coping strategies (Brief-COPE), and depressive symptoms (EPDS). Pearson correlations, hierarchical multiple regression, and moderation analyses were conducted. Main Outcome Measures: Symptoms of antenatal depression measured by the Edinburgh Postnatal Depression Scale (EPDS). Results: Higher levels of negative anticipation and fear of childbirth were positively associated with depressive symptoms, while greater psychological flexibility was negatively associated. Avoidant coping strategies were linked to higher depressive symptoms, whereas problem-focused coping showed a marginal protective effect. Hierarchical regression indicated that negative anticipation and fear of childbirth, psychological flexibility, and avoidant coping strategies were significant independent predictors of depressive symptoms. The moderation analysis revealed that psychological flexibility did not significantly moderate the association between fear of childbirth and depressive symptoms (p = .296). However, conditional effects suggested that among women with low psychological flexibility, negative anticipation and fear of childbirth seems to be more strongly associated with depressive symptoms. Conclusions: Psychological flexibility appears to play a protective role in emotional adjustment during pregnancy. Enhancing flexibility through targeted interventions could contribute to reducing antenatal depressive symptoms, particularly among women experiencing high fear of childbirth.