Association between placental location and cord insertion site with pre-eclampsia: a retrospective cohort study

Abstract

Abstract Background The relationship between placental location without previa and adverse pregnancy outcomes has not been well studied. Additionally, the impact of abnormal cord insertion sites remains controversial. Therefore, the objective of this study was to explore the adverse outcomes associated with placental location and abnormal cord insertion in nulliparous women and to assess their impact on pregnancy outcomes. Methods This retrospective cohort study was conducted at a single tertiary hospital between January 2019 and June 2022. The study included nulliparous women with singleton pregnancies who delivered live infants and had available data on placental location and umbilical cord insertion site from a second- or third-trimester ultrasound. Placental location was categorized as anterior or posterior using transabdominal ultrasonography. The association between placental location/cord insertion site and pre-eclampsia was evaluated using multivariate logistic regression analysis. We compared the area under the curve to evaluate the impact of placental location and cord insertion site on pre-eclampsia. Results A total of 2219 pregnancies were included in the study. Pre-eclampsia occurred significantly more frequently in the anterior group than in the posterior group (8.21% vs. 3.04%, p<0.001). In multivariate analysis investigating the association between placental location and pre-eclampsia, anterior placenta and marginal cord insertion showed significantly increased odds ratios for pre-eclampsia of 3.05 (95% confidence interval (CI) 1.68–6.58) and 3.64 (95% CI 1.90–6.97), respectively. Receiver operating characteristic (ROC) curves were constructed to predict pre-eclampsia using independent factors from multivariate analyses. Model I, including maternal age, pre-pregnancy body mass index, in vitro fertilization, chronic hypertension, overt diabetes, kidney disease, and hematologic diseases, achieved an area under the ROC curve of 0.70 (95% CI 0.65–0.75). Adding cord insertion site and placental location to the model (Model II) significantly improved its predictive performance, resulting in an area under the ROC curve of 0.749 (95% CI 0.70–0.79, p = 0.02). Conclusions Anterior placenta and marginal cord insertion were significantly associated with an increased risk of pre-eclampsia. Further validation studies in prospective cohorts should be conducted to confirm these findings.