Comparison of Maternal Serum Neuropilin-1 (NRP-1) and Fetal Cord Blood NRP-1 Concentrations in Between Normotensive Pregnant Women and Those with Preeclampsia

<b>Background:</b> The aim of this study was to compare the levels of Neuropilin-1 (NRP-1) in maternal plasma and fetal cord blood plasma between pregnancies complicated by preeclampsia (PE) and those in normotensive pregnant women. <b>Materials and Methods:</b> This prospectively designed study included 53 pregnant women aged 18 years or older and at least 20 weeks into gestation, who were admitted to the Maternity Department of Izmir Katip Çelebi University Atatürk Training and Research Hospital. The patient group consisted of 28 pregnant women who met the diagnostic criteria for PE, while the control group included 25 normotensive pregnant women. The diagnosis of PE was established based on the 2020 diagnostic criteria of the American College of Obstetricians and Gynecologists (ACOG). After detailed anamnesis, blood samples were collected immediately after delivery in EDTA tubes to assess serum NRP-1 levels. These samples included maternal blood, fetal cord blood, and additional tests such as CBC, liver and kidney function tests, serum electrolytes, spot urinalysis, prothrombin time (PT), and activated partial thromboplastin time (APTT). <b>Results:</b> There was a statistically significant difference between the two groups in terms of gestational week, presence of comorbidities, hypertension (HT), diabetes mellitus (DM), history of PE, and protein detected in spot urine examinations. Pregnant women in the PE group had significantly higher rates of comorbidities, HT, and DM compared to the control group (<i>p</i> < 0.001, 0.002, and 0.007, respectively). No statistically significant differences were observed between the two groups regarding hemoglobin, platelet count, aspartate aminotransferase (AST), alanine aminotransferase (ALT), or fetal cord plasma NRP-1 levels (<i>p</i>: 0.736, 0.831, 0.561, and 0.734, respectively). However, a statistically significant difference was found in maternal plasma NRP-1 levels (<i>p</i>: 0.02), which were lower in the control group compared to the PE group (median: 473.3 pg/mL vs. 587.7 pg/mL, respectively). The optimal cut-off value for maternal plasma NRP-1 to predict PE, with the best sensitivity and specificity, was determined to be 358.4 pg/mL. Among the study participants, 40 pregnant women had maternal plasma NRP-1 levels above the cut-off value, while 13 had levels below it. PE occurred significantly more frequently in the high NRP-1 group than in the low group. When demographic and clinical characteristics were analyzed, a statistically significant but weak positive correlation was found between body mass index (BMI) and maternal plasma NRP-1 levels (<i>p</i>: 0.02, Rho: 0.304). No strong or statistically significant relationships were identified with other variables. There was no significant difference in fetal cord plasma NRP-1 levels between the PE group and the normotensive group. In contrast, maternal plasma NRP-1 levels were significantly higher in the PE group. The cut-off value for maternal plasma NRP-1, providing optimal sensitivity and specificity for predicting PE, remained 358.4 pg/mL. <b>Conclusions:</b> While further studies involving larger cohorts of pregnant women from diverse racial backgrounds and various hospitals are needed to better understand the relationship between NRP-1 and PE, maternal NRP-1 concentration shows promise as a diagnostic marker.