Impact of abnormal placentation on the risk of hypertensive disorders in pregnancy: A retrospective analysis

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We aimed to investigate the impact of abnormal placental location and placenta accreta spectrum (PAS) disorders on the incidence of hypertensive disorders of pregnancy. This retrospective, single-center study was conducted at a tertiary maternity hospital between 2018 and 2022. The study population was classified according to abnormal placentation, including control (normal placentation), low-lying placenta (LP), placenta previa (PP), and PAS. The PAS group was further divided into subtypes: accreta, increta, percreta. Logistic regression analysis was performed to evaluate factors influencing the incidence of HDPs and pregnancy-induced hypertension (PIH) and their association with abnormal placentation and PAS subtypes. A total of 337 pregnant women were recruited into the study, with 222 abnormal placentations (85 were classified as LP, 72 as PP and 65 as PAS) and 155 controls. Among the participants, 37 women (9.81%) were diagnosed with HDPs. The incidence of HDPs was significantly lower in the PP (4.2%) and PAS (7.7%) groups compared to the control group (12.3%) (p<0.001). The prevalence rates of HDPs were 10.3% in women without PAS, 11.1% with accreta, 8.7% with increta, and 4.1% with percreta (p<0.001). For PIH, the prevalence rates were 7.4% without PAS, 5.6% with accreta, 4.3% with increta, and 0% with percreta (p<0.001). After adjustment for confounders, including advanced maternal age, nulliparity, gestational diabetes mellitus (GDM), and elevated thyroid-stimulating hormone (TSH) levels, a significant negative association was observed between PP and the risk of PIH (OR=0.215, 95% CI: 0.128–1.243, p=0.001) and HDPs (OR=0.215, 95% CI: 0.128–1.243, p=0.001). Similarly, a negative association was observed between PAS and the risk of PIH (OR = 0.550, 95% CI: 0.295–1.120, p = 0.004) and HDPs (OR=0.610, 95% CI: 0.350–1.320, p=0.004). However, no association was found between HDPs and LP. Abnormal placentation, particularly PP and PAS, is associated with a reduced risk of HDPs, suggesting a potential protective effect. Additionally, the prevalence of HDPs decreases as the invasiveness of PAS increases.