Evaluation of risk factors and pregnancy outcome of placenta previa in a long-term comparative single-center study

Abstract

Objective: Based on the increased rate of Cesarean Sections over the last decades, a higher incidence of placenta previa has been observed. Placenta previa is one of the leading causes of major antepartum bleeding and is associated with increased feto-maternal morbidity rates. Therefore, determining risk factors is essential to improve the outcome of these high-risk pregnancies. This study aimed to determine risk factors and analyze the feto-maternal outcome of women with placenta previa. Methods: A long-term retrospective study was performed at the Obstetric Department of University Hospital Salzburg. Potential risk factors (age, BMI, gravidity/parity, associated comorbidities, prior uterine surgery, prior Cesarean section, prior abortions) of all women diagnosed with placenta previa were analyzed over ten years and compared to a matched control group of women with vaginal delivery. Additionally, the feto-maternal outcome was evaluated. Results: During this study period, 20,567 deliveries were evaluated. Ninety-six cases (0.46%) were identified with abnormal placenta localization, and 46 (0.22%) were diagnosed as placenta previa. There was a significant difference in previous Cesarean deliveries between the two cohorts (PP: 23.9% vs Control: 4.3%, p < 0.014). Regarding previous uterine surgeries in general, no significant differences could be found. Women with placenta previa had significantly longer inpatient stays (mean 21.3 days vs. 2.0 days, p < 0.001) and a higher risk of hemorrhage (hemoglobin 9.4 ± 1.0 vs. 11.5 ± 1.5, p < 0.001). Neonatal outcome was significantly worse with lower Apgar scores (8.4 after 5 min vs. 9.8, p < 0.001) and lower birth weights (2404 ± 671 grams vs 3435 ± 459 grams, p < 0.001). Conclusions: Previous Cesarean Section was confirmed as main risk factor for developing placenta previa in consecutive delivery, while other previous uterine surgeries did not increase the risk. Women with placenta previa had significantly elevated blood loss, and neonates had a higher risk of being transferred to the NICU due to prematurity.