OBJECTIVE: To investigate factors associated with postpartum depression symptoms one year after operative vaginal delivery (OVD). DESIGN: Secondary analysis of the prospective observational INSTRUMODA cohort. SETTING: 111 French maternity units. POPULATION: Nulliparous women who underwent OVD between April 2021 and March 2022, and completed two questionnaires, the first one during the days following delivery and the second at one year. METHODS: Statistical analyses accounted for one-year attrition and missing data. Logistic regression models were constructed using a hierarchical approach, with sequential introduction of covariate groups. MAIN OUTCOME MEASURES: Postpartum depression symptoms defined as an Edinburgh Postnatal Depression Scale score ≥13. RESULTS: The prevalence of postpartum depression symptoms at one year was 21.3% (95%CI [18.4–24.2]). Non-modifiable factors associated with postpartum depression symptoms one year after an OVD were pre-pregnancy body mass index (≥30kg/m 2: adjusted OR=2.37 [1.33–4.24]; 25–30kg/m 2: aOR=2.03 [1.30–3.17]; reference: 18–25kg/m 2) and need for psychological support during postpartum hospital stay (aOR=3.78 [1.64–8.76]). Potentially modifiable factors were high anxiety level prior to OVD (aOR=1.84 [1.05–3.22]), feeling of not consenting to the OVD (aOR=1.58 [1.01–2.49]), and marked difficulties in bonding with the child during the postpartum stay (aOR=3.10 [1.04–9.29]). The obstetrical context (indication for OVD, OVD difficulty and morbidity composites) was not found to be associated with higher depression symptoms at one year. CONCLUSIONS: One woman in five suffers from postpartum depression symptoms one year after OVD. Associated factors include both individual characteristics and aspects of maternal experience, highlighting potential targets for prevention.