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These numbers show the urgency of investing in the quality of fetal health care. The heart rate signal is a complex signal and sometimes behaves unpredictably. Thus, it becomes relevant to study approaches that take into account their complexity, namely non-linear compression-based methods. In this work, feature extraction was based on two approaches: univariate and bivariate. The univariate approach is concerned with the extraction of fetal, maternal and maternal-fetal compression ratios and the bivariate approach aims to extract compression indices from maternal-fetal heart rate simultaneous signals and of each of the signals individually over time. To understand how the features calculated in this work can be useful in distinguishing acidemic and non-acidemic cases, a classifier was applied. Three different classifiers were tested, and the one that proved to be more effective was the Support-Vector Machine. Furthermore, it was also possible to conclude that the input set of variables that provides a better performance (f1-score = 0.793) of the classifier is composed of the variables of maternal-fetal compression ratio, maternal-fetal normalized relative compression and maternal-fetal normalized compression distance, obtained through trend and residual signal, which indicates that slow and fast fluctuations on the heart rate time series are important in acidemia assessment.<\/jats:p>","DOI":"10.1371\/journal.pone.0313709","type":"journal-article","created":{"date-parts":[[2025,1,2]],"date-time":"2025-01-02T19:04:31Z","timestamp":1735844671000},"page":"e0313709","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":1,"title":["Extraction of compression indices from maternal-fetal heart rate simultaneous signals"],"prefix":"10.1371","volume":"20","author":[{"given":"Mariana S.","family":"Ramos","sequence":"first","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8650-9219","authenticated-orcid":true,"given":"Susana","family":"Br\u00e1s","sequence":"additional","affiliation":[]},{"given":"Paula","family":"Pinto","sequence":"additional","affiliation":[]},{"given":"Lu\u00edsa","family":"Castro","sequence":"additional","affiliation":[]}],"member":"340","published-online":{"date-parts":[[2025,1,2]]},"reference":[{"key":"pone.0313709.ref001","first-page":"1","article-title":"Reducing one million child deaths from birth asphyxia\u2014A survey of health systems gaps and priorities","volume":"5","author":"JE Lawn","year":"2007","journal-title":"Health Research Policy and Systems"},{"issue":"03","key":"pone.0313709.ref002","doi-asserted-by":"crossref","first-page":"411","DOI":"10.1142\/S0218213006002746","article-title":"Feature extraction and classification of fetal heart rate using wavelet analysis and support vector machines","volume":"15","author":"G Georgoulas","year":"2006","journal-title":"International Journal on Artificial Intelligence Tools"},{"issue":"October 2018","key":"pone.0313709.ref003","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1016\/j.compbiomed.2019.04.041","article-title":"On the prediction of foetal acidaemia: A spectral analysis-based approach","volume":"109","author":"MN Zarmehri","year":"2019","journal-title":"Computers in Biology and Medicine"},{"issue":"2","key":"pone.0313709.ref004","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/j.jogoh.2016.11.005","article-title":"Understanding fetal physiology and second line monitoring during labor","volume":"46","author":"C Garabedian","year":"2017","journal-title":"Journal of Gynecology Obstetrics and Human Reproduction"},{"issue":"1","key":"pone.0313709.ref005","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1016\/j.ijgo.2015.06.018","article-title":"FIGO consensus guidelines on intrapartum fetal monitoring: Physiology of fetal oxygenation and the main goals of intrapartum fetal monitoring","volume":"131","author":"D Ayres-De-Campos","year":"2015","journal-title":"International Journal of Gynecology and Obstetrics"},{"issue":"18","key":"pone.0313709.ref006","doi-asserted-by":"crossref","first-page":"6","DOI":"10.1097\/01.PGO.0000453617.48477.32","article-title":"Neonatal Encephalopathy and Neurologic Outcome","volume":"34","author":"Gynecologists The American College of Obstetricians and","year":"2014","journal-title":"Postgraduate Obstetrics Gynecology"},{"issue":"7313","key":"pone.0313709.ref007","doi-asserted-by":"crossref","first-page":"625","DOI":"10.1136\/bmj.323.7313.625","article-title":"Complexity science: The challenge of complexity in health care. 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