Associations of First-Trimester Screening Markers and Hematological Indices with Placenta Accreta Spectrum in Pregnancies Complicated by Placenta Previa

<b>Background</b>: Placenta accreta spectrum (PAS) is a serious pregnancy complication associated with significant hemorrhaging and elevated maternal morbidity. Timely prenatal diagnosis is critical for reducing the risk of adverse outcomes. In this study, we aimed to investigate the association between PAS and first-trimester maternal serum screening markers, as well as selected hematological and inflammatory indices, in pregnancies complicated by placenta previa (PP). <b>Methods</b>: A retrospective study was conducted at a tertiary care center. Pregnant women with singleton pregnancies who had been diagnosed with PP and undergone first-trimester aneuploidy screening and delivered at the same institution were included. The participants were divided into two groups: those diagnosed with PAS (including placenta accreta, increta, and percreta) and those with PP without placental invasion. Data on maternal demographics, the first-trimester serum levels of pregnancy-associated plasma protein-A (PAPP-A), and free β-human chorionic gonadotropin (β-hCG), as well as pre-delivery complete blood count parameters, were collected. Associations between these markers and abnormal placental implantation were analyzed. <b>Results</b>: In total, 181 participants were included in this study, corresponding to 15 cases of PAS and 166 cases of non-invasive PP. The women in the PAS group were significantly younger than those in the non-invasive-PP group (25.3 ± 5.1 vs. 30.0 ± 6.3 years, <i>p</i> < 0.001). The serum levels of PAPP-A and free β-hCG were significantly higher in the PAS cases (<i>p</i> < 0.05). The mean platelet volume (MPV) was significantly lower inF the PAS group (<i>p</i> < 0.05). We did not observe any significant differences in other hematological parameters, including hemoglobin concentration, white blood cell count, neutrophil and lymphocyte counts, platelet count, red cell distribution width, and inflammatory ratios such as the neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios. <b>Conclusions</b>: Elevated first-trimester levels of PAPP-A and β-hCG, along with a reduced MPV, may serve as early indicators of PAS in pregnancies complicated by PP. These biomarkers may assist in early risk stratification and help inform perinatal management strategies.