Placental Location and Hypertensive Disorders of Pregnancy: A Narrative Review

Abstract

Background: Hypertensive disorders of pregnancy (HDP), including gestational hypertension and preeclampsia, remain major contributors to maternal and perinatal morbidity and mortality worldwide. Abnormal placentation is recognized as the central mechanism underlying these disorders. Placental location, routinely assessed during second-trimester ultrasonography, has recently gained attention as a simple, non-invasive marker that may reflect uteroplacental perfusion and predict the subsequent development of hypertensive disorders.

Objective: To critically review the available literature regarding the association between placental location and hypertensive disorders of pregnancy, summarize the underlying pathophysiological mechanisms, evaluate current evidence, and discuss the potential clinical implications of incorporating placental location into routine antenatal risk assessment.

Methods: A comprehensive literature search was performed using PubMed/MEDLINE, Scopus, Web of Science, Embase, Google Scholar, and the Cochrane Library for studies published up to June 2026. Original research articles, observational studies, cohort studies, case-control studies, systematic reviews, and meta-analyses evaluating placental location and hypertensive disorders of pregnancy were reviewed. Twenty-five key publications were selected based on scientific relevance and methodological quality.

Results: Most observational studies demonstrated a significant association between lateral placental implantation and an increased risk of hypertensive disorders, particularly preeclampsia. The proposed mechanism involves asymmetric uterine arterial perfusion, impaired spiral artery remodeling, placental ischemia, oxidative stress, angiogenic imbalance, and maternal endothelial dysfunction. Although several prospective studies and recent meta-analyses support placental laterality as a risk-enhancing marker, variability in study design, ultrasound timing, definitions of placental laterality, and sample characteristics has resulted in heterogeneous findings. Current evidence indicates that placental location alone has limited predictive accuracy but may improve risk stratification when combined with maternal clinical characteristics, uterine artery Doppler findings, and biochemical biomarkers.

Conclusion: Placental location is an inexpensive, readily available, and non-invasive ultrasonographic parameter that shows promise as an adjunctive marker for predicting hypertensive disorders of pregnancy. While it should not be used as an independent screening tool, integration of placental location into multimodal prediction models may facilitate earlier identification of high-risk pregnancies and improve maternal and perinatal outcomes. Future large-scale multicenter prospective studies with standardized ultrasonographic criteria are required to establish its role in routine obstetric practice.