Correlation of biological parameters with placental parameters and pregnancy outcomes in pre-eclamptic women

Introduction: Pre-eclampsia is characterized by maternal vascular malperfusion and chronic inflammation in placenta. Our purpose was to investigate the potential correlation of biological parameters with placental parameters and pregnancy outcomes in pre-eclamptic women. Methods: Pre-eclamptic women were identified by interrogation of the Medical Registry Department in six French maternities between April 2013 and June 2018. Histological parameters in placentas (weight, macroscopic and microscopic lesions), baseline maternal characteristics and pregnancy outcomes (course of pregnancy, newborns' characteristics) were collected. Biological parameters were blood cell ratios (Platelet-to-Lymphocyte Ratio (PLR), Neutrophil-to-Lymphocyte Ratio (NLR)) collected at delivery and Placental growth factor (PlGF) measured in women with an available first trimester serum sample. Correlations of blood cell ratios and PlGF levels with placental parameters and pregnancy outcomes were assessed by Pearson's correlation test for quantitative parameters and by logistic regression analysis for qualitative parameters. Results: 202 pregnancies were included, among which 68 had a first trimester PlGF quantification. No correlation was found between biological parameters and placental lesions. Low PLR was correlated with low placental weight (r = 0.156, p = 0.036) and with low birth weight (r = 0.179, p = 0.015). Low PlGF was correlated with long time from pre-eclampsia diagnosis to delivery (r = -0.250, p = 0.048). Conclusions: There is no correlation between biological parameters and placental lesions in pre-eclamptic women. Yet, low PLR at delivery is correlated with low placental and birth weights. Moreover, low first trimester PlGF is correlated with long time from pre-eclampsia diagnosis to delivery.