Background: Placenta accreta spectrum (PAS) disorder is an important life-threatening problem. The purpose of the current study was to determine the frequency, risk factors, and pregnancy outcomes of PAS in our population. Methods: This is a case-control study using the data from a main tertiary referral university hospital in Ahvaz, southwest of Iran. The sample included 187 cases diagnosed with placenta accreta spectrum from 2015 to 2019 and 552 controls without PAS. A multivariable logistic regression model was used to find independent risk factors with 95% confidence interval. Pregnancy outcomes were evaluated using chi-square, t-test, and Mann-Whitney U test and p<0.05 were considered statistically significant. Results: The frequency of PAS during the study period was 3.7/1000 deliveries (0.37%). It was found that multiparity (≥3 deliveries, OR=2.05: 95%CI:1.21-3.47) and multigravidity (≥3 deliveries, OR=2.98: 95%CI:1.55-5.72), prior cesarean delivery (OR=52.55: 95%CI:19.73-139.96), and placenta previa (OR=27.48: 95%CI:9.62-78.5) are the independent risk factors of PAS. Complications and morbidity associated with PAS included hysterectomy (60.4% vs. 0.7%, p<0.001), cystostomy (24.1% vs. 0.2%, p<0.001), the need for blood transfusion (73.7% vs. 1.4%, p<0.001), intensive care unit admission of mother (42.8% vs. 0.2%, p<0.001), duration of hospitalization (7.52±6.34 vs. 1.97±1.83, p<0.001), preterm birth <37 weeks (61.4% vs. 16.8%, p<0.001), and perinatal mortality (7.4% vs. 1.8%, p<0.001) which manifested statistically significant values. Conclusion: The frequency of PAS is similar to other populations. Prior cesarean delivery, placenta previa, multigravidity, and multiparity were independent risk factors and also perinatal hysterectomy and preterm birth were the most important complications.