Characterization of systolic and diastolic pressure time series in pregnant women with preeclampsia through symbolic dynamics. Daniel Ch´ avez-Leyva 1 , Guadalupe Dorantes-M´ endez 1 , Samantha Alvarado-Jalomo 2 , Lisbeth Camargo-Mar´ ın 3 , and Mercedes J. Gait´ an-Gonz´ alez 4 Abstract— Preeclampsia (PE) is one of the leading causes of maternal mortality worldwide. Although clinical strategies to prevent the early onset of PE have been proposed, the ultimate solution is to end the pregnancy. Therefore, patients’ identification with major PE risk is important towards the prevention and better management of a severe manifestation of the illness. This study aims to analyze the systolic blood pressure (SBP) and diastolic blood pressure (DBP) time series through a nonlinear perspective using symbolic dynamics and to incorporate a multi-scale assessment in the first trimester of pregnancy, previous to the clinical manifestation of PE. The study group of normotensive women who developed and were diagnosed with PE included 14 pregnant women, a normotensive throughout pregnancy control group (N) consisting of 14 participants, and a group of 14 normotensive women during pregnancy without comorbidities (S) were matched with PE by age, body mass index, gestational age and comorbidities. The preliminary results of this study showed a decreased complexity of SBP, assessed by multiscale symbolic entropy in the first trimester in PE patients, in comparison with normotensive pregnant women. Clinical relevance— This work shows how nonlinear analysis of systolic and diastolic blood pressure time series are useful to detect preeclampsia in the first trimester of pregnancy. I. INTRODUCTION During the pregnancy, maternal autonomic cardiovascular control changes occur with the aim to optimize maternal and fetal oxygen and nutrients support. However, these cardio- vascular control mechanisms can be disturbed, generating hypertensive disorders such as Preeclampsia (PE), which is a common multisystem disorder defined by the presence of high blood pressure (BP) after week 20 of pregnancy accom- panied by signs such as proteinuria, severe headaches, vision affections, nausea, vomiting, thrombocytopenia, symptoms of liver or kidney damage, among others [1]. PE is one of the leading causes of maternal mortality worldwide. In Latin America and the Caribbean, 25.7% of * D. Ch´ avez Leyva is supported by CONACyT Master fellowship with #1006950. 1 D. Ch´ avez-Leyva and G. Dorantes-M´ endez are with Faculty of Sciences, Autonomous University of San Luis Potosi (UASLP), S.L.P., Mexico. 2 S Alvarado-Jalomo is with Basic Sciences and Engineering Department, Universidad Aut´ onoma Metropolitana (UAM), CDMX, Mexico. 3 L Camargo-Mar´ ın is with Translational Medicine Department, Instituto Nacional de Perinatolog´ ıa, CDMX, Mexico. 4 J Gait´ an-Gonz´ alez is with Health Sciences Department, Universidad Aut´ onoma Metropolitana (UAM), CDMX, Mexico. Corresponding author e-mail: guadalupe.dorantes@uaslp.mx, emails: danielchavezleyva@gmail.com, samantha.alvaradojalomo@gmail.com, lisbethcamargo@yahoo.com.mx, jatziri.gaitan@gmail.com. maternal deaths are attributed to PE and in Mexico this percentage rises up to 34% [2]. Clinical manifestation of PE typically begins at the second trimester. However, an average of 21% of the patients with mild PE and 6% with severe PE may be asymptomatic [2]. Although clinical strategies to prevent early onset of PE have been proposed, the ultimate solution is to end pregnancy, which in some cases can result in adverse perinatal outcomes and maternal complications. Therefore, patients’ identification with major PE risk is important towards the prevention and better management of a severe manifestation of the illness. Blood pressure variability (BPV) has been studied to de- scribe normal pregnancies and pregnancies with hypertensive disorders, such as PE. Increase in BPV has been reported in PE patients compared to normotensive pregnant women [3], [4]. Most of the studies regarding PE are performed when the disease is clinically manifested. However, Hermida et al. [4] showed that differences in BP between healthy and complicated pregnancies can be observed as early as in the first trimester of pregnancy and Malberg et al. [5] were able to predict PE with a predictive value of 70% several weeks before clinical manifestations, in the period between the 18th and 26th weeks of pregnancy, based on variability indexes and baroreflex parameters. Also, elevated first trimester systolic BPV was associated with PE [6]. The pathophysiologic processes in PE are a result of multiple factors and nonlinear interactions of different phys- iological regulations and systems could be present. There- fore, a nonlinear method could help to elucidate additional information about the behavior of systolic blood pressure (SBP) and diastolic blood pressure (DBP), considering also that biological systems operate across multiple scales of space and time. In this context, Faber et al. [3] reported a decrease of low-variability patterns in PE in comparison with healthy pregnant women using symbolic dynamics, while the joint symbolic dynamics (JSD) method was capable of demonstrating differences in the autonomic regulation between normal pregnancies and PE in the second and third trimester [7]. Thus, the aim of this study is to analyze the SBP and DBP time series by means of a nonlinear perspective using sym- bolic dynamics and to incorporate a multi scale assessment in the first trimester of pregnancy previous to the clinical manifestation of PE. 2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) Oct 31 - Nov 4, 2021. Virtual Conference 978-1-7281-1178-0/21/$31.00 ©2021 IEEE 5638