Postpartum post-traumatic stress disorder (PTSD) is not a specific process but can last for months and may manifest itself during any subsequent pregnancies or even become chronic. This study aimed to determine the factors associated with long-term PTSD symptoms one year after delivery. A cross-sectional study was conducted on 1301 Spanish puerperal women. Data were collected on sociodemographic, obstetric, and neonatal variables. The Perinatal Post-Traumatic Stress Disorder Questionnaire (PPQ) was administered online through midwives’ associations across Spain. Crude odds ratio (OR) and adjusted odds ratio (aOR) and their 95% confidence intervals were calculated. A PPQ score ≥ 19 (high-risk) was recorded for 13.1% (171) of the participants. Identified risk factors were not respecting a birth plan (aOR = 1.89 (95% CI 1.21–2.94)), formula-feeding of the baby at discharge (aOR = 2.50 (95% CI 1.20–5.17)), postpartum surgical intervention (aOR = 2.23 (95% CI 1.02–4.85)), hospital readmission (aOR = 3.45 (95% CI 1.21–9.84)), as well as verbal obstetric violence (aOR = 3.73 (95% CI 2.52–5.53)) and psycho-affective obstetric violence (aOR = 3.98 (95% CI 2.48–6.39)). During childbirth, some clinical practices, such as formula-feeding of the newborn at discharge or types of obstetric violence towards the mother, were associated with a higher risk of PTSD symptoms one year after delivery.