On the outbreak of the global COVID-19 pandemic, high-risk and vulnerable groups in the population were at particular risk of severe disease progression. Pregnant women were one of these groups. The infectious disease endangered not only the physical health of pregnant women, but also their mental well-being. Improving the mental health of pregnant women and reducing their risk of an infectious disease could be achieved by using remote home monitoring solutions. These would allow the health of the mother and fetus to be monitored from the comfort of their home, a reduction in the number of physical visits to the doctor and thereby eliminate the need for the mother to venture into high-risk public places. The most commonly used technique in clinical practice, cardiotocography, suffers from low specificity and requires skilled personnel for the examination. For that and due to the intermittent and active nature of its measurements, it is inappropriate for continuous home monitoring. The pandemic has demonstrated that the future lies in accurate remote monitoring and it is therefore vital to search for an option for fetal monitoring based on state-of-the-art technology that would provide a safe, accurate, and reliable information regarding fetal and maternal health state. In this paper, we thus provide a technical and critical review of the latest literature and on this topic to provide the readers the insights to the applications and future directions in fetal monitoring. We extensively discuss the remaining challenges and obstacles in future research and in developing the fetal monitoring in the new era of Fetal monitoring 4.0, based on the pillars of Healthcare 4.0.

Department of Computer Science Faculty of Electrical Engineering and Computer Science VSB Technical University of Ostrava Ostrava Czechia

Department of Cybernetics and Biomedical Engineering Faculty of Electrical Engineering and Computer Science VSB Technical University of Ostrava Ostrava Czechia

Department of Pediatrics Faculty Hospital Faculty of Medicine Ostrava University Ostrava Czechia

Zobrazit více v PubMed

Goyder C. COVID-19: Crystallising the Importance of Patient Safety. Br J Gen Pract. 2020;70(698):449. doi: 10.3399/bjgp20X712373. PubMed DOI PMC

World Health Organization. Coronavirus disease (COVID-19): pregnancy and childbirth: World Health Organization; 2020. Available: https://www.who.int/. Accessed 1 Jan 2022.

Lebel C, MacKinnon A, Bagshawe M, Tomfohr-Madsen L, Giesbrecht G. Elevated Depression and Anxiety Symptoms among Pregnant Individuals during the COVID-19 Pandemic. J Affect Disord. 2020;277:5–13. doi: 10.1016/j.jad.2020.07.126. PubMed DOI PMC

Moyer CA, Compton SD, Kaselitz E, Muzik M. Pregnancy-Related Anxiety during COVID-19: A Nationwide Survey of 2740 Pregnant Women. Arch Womens Mental Health. 2020;23(6):757–765. doi: 10.1007/s00737-020-01073-5. PubMed DOI PMC

Salehi L, Rahimzadeh M, Molaei E, Zaheri H, Esmaelzadeh-Saeieh S. The Relationship among Fear and Anxiety of COVID-19, Pregnancy Experience, and Mental Health Disorder in Pregnant Women: A Structural Equation Model. Brain Behav. 2020;10(11). 10.1002/brb3.1835. PubMed PMC

Abdoli A, Falahi S, Kenarkoohi A, Shams M, Mir H, Jahromi MAM. The COVID-19 Pandemic, Psychological Stress during Pregnancy, and Risk of Neurodevelopmental Disorders in Offspring: A Neglected Consequence. J Psychosom Obstet Gynecol. 2020;41(3):247–248. doi: 10.1080/0167482X.2020.1761321. PubMed DOI

Mortazavi F, Mehrabadi M, KiaeeTabar R. Pregnant Women’s Well-Being and Worry during the COVID-19 Pandemic: A Cross-Sectional Study. BMC Pregnancy Childbirth. 2021;21(1):59. doi: 10.1186/s12884-021-03548-4. PubMed DOI PMC

Asai K, Wakashima K, Toda S, Koiwa K. Fear of Novel Coronavirus Disease (COVID-19) among Pregnant and Infertile Women in Japan. J Affect Disord Rep. 2021;4:100104. doi: 10.1016/j.jadr.2021.100104. PubMed DOI PMC

Nausheen S, Bhamani S, Makhdoom A, Sheikh L. Fear of COVID-19 among Pregnant Women in Pakistan: A Cross-Sectional Study. Int J Community Med Public Health. 2020;7(12):4749. doi: 10.18203/2394-6040.ijcmph20205145. DOI

Cardwell MS. Stress: Pregnancy Considerations. Obstet Gynecol Surv. 2013;68(2):119–129. doi: 10.1097/OGX.0b013e31827f2481. PubMed DOI

Coussons-Read ME. Effects of Prenatal Stress on Pregnancy and Human Development: Mechanisms and Pathways. Obstet Med. 2013;6(2):52–57. doi: 10.1177/1753495x12473751. PubMed DOI PMC

Yu Y, Zhang S, Wang G, Hong X, Mallow EB, Walker SO, et al. The Combined Association of Psychosocial Stress and Chronic Hypertension with Preeclampsia. Am J Obstet Gynecol. 2013;209(5):438.e1–438.e12. doi: 10.1016/j.ajog.2013.07.003. PubMed DOI PMC

Ben-Ami I, Maymon R, Svirsky R, Cuckle H, Jauniaux E. Down Syndrome Screening in Assisted Conception Twins: An Iatrogenic Medical Challenge. Obstet Gynecol Surv. 2013;68(11):764–773. doi: 10.1097/OGX.0000000000000001. PubMed DOI

Dunkel Schetter C, Tanner L. Anxiety, Depression and Stress in Pregnancy: Implications for Mothers, Children, Research, and Practice. Curr Opin Psychiatry. 2012;25(2):141–148. doi: 10.1097/YCO.0b013e3283503680. PubMed DOI PMC

de Weerth C, Buitelaar JK. Physiological Stress Reactivity in Human Pregnancy–a Review. Neurosci Biobehav Rev. 2005;29(2):295–312. doi: 10.1016/j.neubiorev.2004.10.005. PubMed DOI

Dashraath P, Wong JLJ, Lim MXK, Lim LM, Li S, Biswas A, et al. Coronavirus Disease 2019 (COVID-19) Pandemic and Pregnancy. Am J Obstet Gynecol. 2020;222(6):521–531. doi: 10.1016/j.ajog.2020.03.021. PubMed DOI PMC

Chiu NC, Chi H, Tai YL, Peng CC, Tseng CY, Chen CC, et al. Impact of Wearing Masks, Hand Hygiene, and Social Distancing on Influenza, Enterovirus, and All-Cause Pneumonia During the Coronavirus Pandemic: Retrospective National Epidemiological Surveillance Study. J Med Internet Res. 2020;22(8):e21257. doi: 10.2196/21257. PubMed DOI PMC

Alimohamadi Y, Holakouie-Naieni K, Sepandi M, Taghdir M. Effect of Social Distancing on COVID-19 Incidence and Mortality in Iran Since February 20 to May 13, 2020: An Interrupted Time Series Analysis. Risk Manag Healthc Policy. 2020;13:1695–1700. doi: 10.2147/RMHP.S265079. PubMed DOI PMC

Sun B, Yeh J. Mild and Asymptomatic Covid-19 Infections: Implications for Maternal, Fetal, and Reproductive Health. Front Reprod Health. 2020;2:1. doi: 10.3389/frph.2020.00001. PubMed DOI PMC

Yee J, Kim W, Han JM, Yoon HY, Lee N, Lee KE, et al. Clinical Manifestations and Perinatal Outcomes of Pregnant Women with COVID-19: A Systematic Review and Meta-Analysis. Scientific Reports. 2020;10(1):18126. doi: 10.1038/s41598-020-75096-4. PubMed DOI PMC

Wastnedge EAN, Reynolds RM, van Boeckel SR, Stock SJ, Denison FC, Maybin JA, et al. Pregnancy and COVID-19. Physiol Rev. 2021;101(1):303–318. doi: 10.1152/physrev.00024.2020. PubMed DOI PMC

Adhikari EH, Moreno W, Zofkie AC, MacDonald L, McIntire DD, Collins RRJ, et al. Pregnancy Outcomes Among Women With and Without Severe Acute Respiratory Syndrome Coronavirus 2 Infection. JAMA Netw Open. 2020;3(11):e2029256. doi: 10.1001/jamanetworkopen.2020.29256. PubMed DOI PMC

Panahi L, Amiri M, Pouy S. Risks of Novel Coronavirus Disease (COVID-19) in Pregnancy; a Narrative Review. Arch Acad Emerg Med. 2020;8(1). 10.22037/aaem.v8i1.595. PubMed PMC

Karavadra B, Stockl A, Prosser-Snelling E, Simpson P, Morris E. Women’s Perceptions of COVID-19 and Their Healthcare Experiences: A Qualitative Thematic Analysis of a National Survey of Pregnant Women in the United Kingdom. BMC Pregnancy and Childbirth. 2020;20(1):600. doi: 10.1186/s12884-020-03283-2. PubMed DOI PMC

Tirachini A, Cats O. COVID-19 and Public Transportation: Current Assessment, Prospects, and Research Needs. J Public Transp. 2020;22(1). 10.5038/2375-0901.22.1.1. PubMed PMC

Ahmad T, Khan M, Haroon, Musa TH, Nasir S, Hui J, et al. COVID-19: Zoonotic Aspects. Travel Med Infect Dis. 2020;36:101607. 10.1016/j.tmaid.2020.101607. PubMed PMC

on behalf of COVID-19 Evidence and Recommendations Working Group, Zhou Q, Gao Y, Wang X, Liu R, Du P, et al. Nosocomial Infections among Patients with COVID-19, SARS and MERS: A Rapid Review and Meta-Analysis. Annals of Translational Medicine. 2020;8(10):629. 10.21037/atm-20-3324. PubMed PMC

Ji H, Liu L, Huang T, Zhu Y. Nosocomial Infections in Psychiatric Hospitals during the COVID-19 Outbreak. Eur J Psychiatr. 2020;34(3):177–179. doi: 10.1016/j.ejpsy.2020.04.001. PubMed DOI PMC

Rickman HM, Rampling T, Shaw K, Martinez-Garcia G, Hail L, Coen P, et al. Nosocomial Transmission of Coronavirus Disease 2019: A Retrospective Study of 66 Hospital-Acquired Cases in a London Teaching Hospital. Clinical Infectious Diseases. 2021;72(4):690–693. doi: 10.1093/cid/ciaa816. PubMed DOI PMC

Wang X, Zhou Q, He Y, Liu L, Ma X, Wei X, et al. Nosocomial Outbreak of COVID-19 Pneumonia in Wuhan, China. Eur Respir J. 2020;55(6):2000544. doi: 10.1183/13993003.00544-2020. PubMed DOI PMC

Klompas M. Coronavirus Disease 2019 (COVID-19): Protecting Hospitals From the Invisible. Ann Intern Med. 2020;172(9):619–620. doi: 10.7326/M20-0751. PubMed DOI PMC

Van Praet JT, Claeys B, Coene AS, Floré K, Reynders M. Prevention of Nosocomial COVID-19: Another Challenge of the Pandemic. Infect Control Hosp Epidemiol. 2020;41(11):1355–1356. doi: 10.1017/ice.2020.166. PubMed DOI PMC

Nosratabadi M, Sarabi N, Masoudiyekta L. A Case Report of Vaginal Delivery at Home Due to Fear of Covid-19. Iran J Psychiatry. 2020. 10.18502/ijps.v15i4.4306. PubMed PMC

Hossain N, Samuel M, Sandeep R, Imtiaz S, Zaheer S. Perceptions, Generalized Anxiety and Fears of Pregnant Women about Corona Virus Infection in the Heart of Pandemic. 2020. 10.21203/rs.3.rs-32235/v1.

Madjunkov M, Dviri M, Librach C. A Comprehensive Review of the Impact of COVID-19 on Human Reproductive Biology, Assisted Reproduction Care and Pregnancy: A Canadian Perspective. J Ovarian Res. 2020;13(1):140. doi: 10.1186/s13048-020-00737-1. PubMed DOI PMC

Kotlyar AM, Grechukhina O, Chen A, Popkhadze S, Grimshaw A, Tal O, et al. Vertical Transmission of Coronavirus Disease 2019: A Systematic Review and Meta-Analysis. Am J Obstet Gynecol. 2021;224(1):35–53.e3. doi: 10.1016/j.ajog.2020.07.049. PubMed DOI PMC

Vivanti AJ, Vauloup-Fellous C, Prevot S, Zupan V, Suffee C, Do Cao J, et al. Transplacental Transmission of SARS-CoV-2 Infection. Nat Commun. 2020;11(1):3572. doi: 10.1038/s41467-020-17436-6. PubMed DOI PMC

Ashraf MA, Keshavarz P, Hosseinpour P, Erfani A, Roshanshad A, Pourdast A, et al. Coronavirus Disease 2019 (COVID-19): A Systematic Review of Pregnancy and the Possibility of Vertical Transmission. J Reprod Infertility. 2020;21(3):157. PubMed PMC

Nowacka U, Kozlowski S, Januszewski M, Sierdzinski J, Jakimiuk A, Issat T. COVID-19 Pandemic-Related Anxiety in Pregnant Women. Int J Environ Res Public Health. 2021;18(14):1–10. doi: 10.3390/ijerph18147221. PubMed DOI PMC

Wu D, Fang D, Wang R, Deng D, Liao S. Management of Pregnancy during the COVID-19 Pandemic. Glob Challenges. 2021;5(2):1–8. doi: 10.1002/gch2.202000052. PubMed DOI PMC

Al-Jaroodi J, Mohamed N, Abukhousa E. Health 4.0. IEEE Access. 2020;8:211189–211210. doi: 10.1109/ACCESS.2020.3038858. PubMed DOI PMC

Li J, Carayon P. Health Care 4.0: A Vision for Smart and Connected Health Care. IISE Trans Healthc Syst Eng. 2021;1–10. 10.1080/24725579.2021.1884627. PubMed PMC

Embracing Healthcare 4.0. https://www.siemens-healthineers.com/insights/news/embracing-healthcare-4-0.html. Accessed 30 Mar 2022.

Hathaliya JJ, Tanwar S, Tyagi S, Kumar N. Securing Electronics Healthcare Records in Healthcare 4.0 : A Biometric-Based Approach. Comput Electr Eng. 2019;76:398–410. doi: 10.1016/j.compeleceng.2019.04.017. DOI

Schmidt JV, McCartney PR. History and Development of Fetal Heart Assessment. J Obstet Gynecol Neonatal Nurs. 2000;29(3):295–305. doi: 10.1111/j.1552-6909.2000.tb02051.x. PubMed DOI

Alfirevic Z, Gyte GM, Cuthbert A, Devane D. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database Syst Rev. 2019;2019(5). 10.1002/14651858.CD006066.pub3. PubMed

Smith VJ, Marshall A, Lie M, Bidmead E, Beckwith B, Van Oudgaarden E, et al. Implementation of a fetal ultrasound telemedicine service: women’s views and family costs. BMC Pregnancy Childbirth. 2021;21(1):1–8. doi: 10.1186/s12884-020-03532-4. PubMed DOI PMC

Mhajna M, Schwartz N, Levit-Rosen L, Warsof S, Lipschuetz M, Jakobs M, et al. Wireless, Remote Solution for Home Fetal and Maternal Heart Rate Monitoring. Am J Obstet Gynecol MFM. 2020;2(2):100101. doi: 10.1016/j.ajogmf.2020.100101. PubMed DOI

Al-Turjman F, Nawaz MH, Ulusar UD. Intelligence in the Internet of Medical Things era. Comput Commun. 2020;150:644–660. doi: 10.1016/j.comcom.2019.12.030. DOI

Cömert Z, Kocamaz A. A Study of Artificial Neural Network Training Algorithms for Classification of Cardiotocography Signals. Bitlis Eren Univ J Sci Technol. 2017;7(2):93–103. 10.17678/beuscitech.338085.

Marzbanrad F, Stroux L, Clifford GD. Cardiotocography and beyond: A Review of One-Dimensional Doppler Ultrasound Application in Fetal Monitoring. Physiol Meas. 2018;39(8):08TR01. doi: 10.1088/1361-6579/aad4d1. PubMed DOI PMC

Kovács F, Horváth C, Balogh ÁT, Hosszú G. Fetal Phonocardiography—Past and Future Possibilities. Comput Methods Programs Biomed. 2011;104(1):19–25. doi: 10.1016/j.cmpb.2010.10.006. PubMed DOI

Várady P, Wildt L, Benyó Z, Hein A. An Advanced Method in Fetal Phonocardiography. Comput Methods Prog Biomed. 2003;71(3):283–296. doi: 10.1016/S0169-2607(02)00111-6. PubMed DOI

Maulik D, Nanda NC, Maulik D, Vilchez G. A Brief History of Fetal Echocardiography and Its Impact on the Management of Congenital Heart Disease. Echocardiography (Mount Kisco, NY). 2017;34(12):1760–1767. doi: 10.1111/echo.13713. PubMed DOI

Lee MY, Won HS. Technique of Fetal Echocardiography. Obstet Gynecol Sci. 2013;56(4):217. doi: 10.5468/ogs.2013.56.4.217. PubMed DOI PMC

Satomi G. Guidelines for Fetal Echocardiography: Guidelines for Fetal Echocardiography. Pediatr Int. 2015;57(1):1–21. doi: 10.1111/ped.12467. PubMed DOI

Peters MJ, Stinstra JG, Uzunbajakau S, Srinivasan N. Fetal Magnetocardiography. In: Lin JC, editor. Advances in Electromagnetic Fields in Living Systems. vol. 4. New York: Springer-Verlag; 2005. p. 1–40. 10.1007/0-387-24024-1_1.

Strasburger JF, Cheulkar B, Wakai RT. Magnetocardiography for Fetal Arrhythmias. Heart Rhythm Off J Heart Rhythm Soc. 2008;5(7):1073–1076. doi: 10.1016/j.hrthm.2008.02.035. PubMed DOI PMC

Quartero HWP, Stinstra JG, Golbach EGM, Meijboom EJ, Peters MJ. Clinical Implications of Fetal Magnetocardiography: Clinical Use of Fetal MCG. Ultrasound Obstet Gynecol. 2002;20(2):142–153. doi: 10.1046/j.1469-0705.2002.00754.x. PubMed DOI

Abdulhay EW, Oweis RJ, Alhaddad AM, Sublaban FN, Radwan MA, Almasaeed HM. Non-Invasive Fetal Heart Rate Monitoring Techniques: Review Article. Biomed Sci Eng. 2014;2:53–67.

Kahankova R, Martinek R, Jaros R, Behbehani K, Matonia A, Jezewski M, et al. A Review of Signal Processing Techniques for Non-Invasive Fetal Electrocardiography. IEEE Rev Biomed Eng. 2020;13:51–73. doi: 10.1109/RBME.2019.2938061. PubMed DOI

Hamelmann P, Kolen A, Schmitt L, Vullings R, van Assen H, Mischi M, et al. Ultrasound Transducer Positioning Aid for Fetal Heart Rate Monitoring. In: 2016 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC). Orlando: IEEE; 2016. p. 4105–4108. 10.1109/EMBC.2016.7591629. PubMed

Cohen WR, Hayes-Gill B. Influence of maternal body mass index on accuracy and reliability of external fetal monitoring techniques. Acta Obstet Gynecol Scand. 2014;93(6):590–595. doi: 10.1111/aogs.12387. PubMed DOI

Sameni. A Review of Fetal ECG Signal Processing Issues and Promising Directions. Open Pacing Electrophysiol Ther J. 2010. 10.2174/1876536X01003010004. PubMed PMC

Okada DM, Chow AW, Bruce VT. Neonatal Scalp Abscess and Fetal Monitoring: Factors Associated with Infection. Am J Obstet Gynecol. 1977;129(2):185–189. doi: 10.1016/0002-9378(77)90742-6. PubMed DOI

Graatsma E, Miller J, Mulder E, Harman C, Baschat A, Visser G. Maternal Body Mass Index Does Not Affect Performance of Fetal Electrocardiography. Am J Perinatol. 2010;27(07):573–577. doi: 10.1055/s-0030-1248945. PubMed DOI

Barnova K, Martinek R, Jaros R, Kahankova R, Matonia A, Jezewski M, et al. A Novel Algorithm Based on Ensemble Empirical Mode Decomposition for Non-Invasive Fetal ECG Extraction. PLoS ONE. 2021;16(8):e0256154. doi: 10.1371/journal.pone.0256154. PubMed DOI PMC

Jaros R, Martinek R, Kahankova R, Koziorek J. Novel Hybrid Extraction Systems for Fetal Heart Rate Variability Monitoring Based on Non-Invasive Fetal Electrocardiogram. IEEE Access Pract Innovations Open Solutions. 2019;7:131758–131784. doi: 10.1109/ACCESS.2019.2933717. DOI

Barnova K, Martinek R, Jaros R, Kahankova R, Behbehani K, Snasel V. System for Adaptive Extraction of Non-Invasive Fetal Electrocardiogram. Appl Soft Comput. 2021;113:107940. doi: 10.1016/j.asoc.2021.107940. DOI

Gobillot S, Fontecave-Jallon J, Equy V, Rivet B, Gumery PY, Hoffmann P. Non-Invasive Fetal Monitoring Using Electrocardiography and Phonocardiography: A Preliminary Study. J Gynecol Obstet Hum Reprod. 2018;47(9):455–459. doi: 10.1016/j.jogoh.2018.08.009. PubMed DOI

Castillo E, Morales DP, García A, Parrilla L, Ruiz VU, Álvarez-Bermejo JA. A Clustering-Based Method for Single-Channel Fetal Heart Rate Monitoring. PLoS ONE. 2018;13(6):e0199308. doi: 10.1371/journal.pone.0199308. PubMed DOI PMC

Gurve D, Krishnan S. Separation of Fetal-ECG From Single-Channel Abdominal ECG Using Activation Scaled Non-Negative Matrix Factorization. IEEE J Biomed Health Inform. 2020;24(3):669–680. doi: 10.1109/JBHI.2019.2920356. PubMed DOI

Da Poian G, Bernardini R, Rinaldo R. Separation and Analysis of Fetal-ECG Signals From Compressed Sensed Abdominal ECG Recordings. IEEE Trans Biomed Eng. 2016;63(6):1269–1279. doi: 10.1109/TBME.2015.2493726. PubMed DOI

Signorini M, Lanzola G, Torti E, Fanelli A, Magenes G. Antepartum Fetal Monitoring through a Wearable System and a Mobile Application. Technologies. 2018;6(2):44. doi: 10.3390/technologies6020044. DOI

Corona-Figueroa A. A Portable Prototype for Diagnosing Fetal Arrhythmia. Inform Med Unlocked. 2019;17:100268. doi: 10.1016/j.imu.2019.100268. DOI

Yuan L, Yuan Y, Zhou Z, Bai Y, Wu S. A Fetal ECG Monitoring System Based on the Android Smartphone. Sensors. 2019;19(3):446. doi: 10.3390/s19030446. PubMed DOI PMC

Rashkovska A, Avbelj V. Abdominal Fetal ECG Measured with Differential ECG Sensor. In: 2017 40th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO). Opatija: IEEE; 2017. p. 289–291. 10.23919/MIPRO.2017.7973436.

Theodoridou A. Current Methods of Non-Invasive Fetal Heart Rate Surveillance. Clinical and Experimental Obstetrics & Gynecology. 2020;47(4):459. 10.31083/j.ceog.2020.04.5422.

Kapaya H, Dimelow ER, Anumba D. Women’s Experience of Wearing a Portable Fetal-Electrocardiogram Device to Monitor Small-for-Gestational Age Fetus in Their Home Environment. Womens Health. 2018;14:174550651878562. doi: 10.1177/1745506518785620. PubMed DOI PMC

GE Healthcare Systems. https://www.gehealthcare.com. Accessed 30 Mar 2022.

Mindchild. https://www.mindchild.com. Accessed 30 Mar 2022.

Sulas E, Urru M, Tumbarello R, Raffo L, Sameni R, Pani D. A Non-Invasive Multimodal Foetal ECG–Doppler Dataset for Antenatal Cardiology Research. Sci Data. 2021;8(1):30. doi: 10.1038/s41597-021-00811-3. PubMed DOI PMC

Nemo Healthcare. https://nemohealthcare.com. Accessed 30 Mar 2022.

Vullings R, van Laar JOEH. Non-Invasive Fetal Electrocardiography for Intrapartum Cardiotocography. Front Pediatr. 2020;8:599049. doi: 10.3389/fped.2020.599049. PubMed DOI PMC

Avalon beltless feotal monitoring solution. Philips. Available: https://www.philips.co.uk/healthcare/product/HC866488/avalon-beltless-feotal-monitoring-solution. Accessed 1 Jan 2022.

Martinek R, Kahankova R, Nazeran H, Konecny J, Jezewski J, Janku P, et al. Non-Invasive Fetal Monitoring: A Maternal Surface ECG Electrode Placement-Based Novel Approach for Optimization of Adaptive Filter Control Parameters Using the LMS and RLS Algorithms. Sensors. 2017;17(5):1154. doi: 10.3390/s17051154. PubMed DOI PMC

Aggarwal G, Wei Y. Non-Invasive Fetal Electrocardiogram Monitoring Techniques: Potential and Future Research Opportunities in Smart Textiles. Signals. 2021;2(3):392–412. doi: 10.3390/signals2030025. DOI

Kubicek J, Fiedorova K, Vilimek D, Cerny M, Penhaker M, Janura M, et al. Recent Trends, Construction and Applications of Smart Textiles and Clothing for Monitoring of Health Activity: A Comprehensive Multidisciplinary Review. IEEE Rev Biomed Eng. 2020;1. 10.1109/RBME.2020.3043623. PubMed

Stoppa M, Chiolerio A. Wearable Electronics and Smart Textiles: A Critical Review. Sensors. 2014;14(7):11957–11992. doi: 10.3390/s140711957. PubMed DOI PMC

Zarzoso V, Nandi AK. Noninvasive Fetal Electrocardiogram Extraction: Blind Separation versus Adaptive Noise Cancellation. IEEE Trans Biomed Eng. 2001;48(1):12–18. doi: 10.1109/10.900244. PubMed DOI

Martín-Clemente R, Camargo-Olivares JL, Hornillo-Mellado S, Elena M, Román I. Fast Technique for Noninvasive Fetal ECG Extraction. IEEE Trans Biomed Eng. 2011;58(2):227–230. doi: 10.1109/TBME.2010.2059703. PubMed DOI

Ghobadi Azbari P, Mohaqeqi S, Ghanbarzadeh Gashti N, Mikaili M. Introducing a Combined Approach of Empirical Mode Decomposition and PCA Methods for Maternal and Fetal ECG Signal Processing. J Matern-Fetal Neonatal Med. 2016;29(19):3104–3109. doi: 10.3109/14767058.2015.1114089. PubMed DOI

Wu S, Shen Y, Zhou Z, Lin L, Zeng Y, Gao X. Research of Fetal ECG Extraction Using Wavelet Analysis and Adaptive Filtering. Comput Biol Med. 2013;43(10):1622–1627. doi: 10.1016/j.compbiomed.2013.07.028. PubMed DOI

Assaleh K. Extraction of Fetal Electrocardiogram Using Adaptive Neuro-Fuzzy Inference Systems. IEEE Trans Biomed Eng. 2007;54(1):59–68. doi: 10.1109/TBME.2006.883728. PubMed DOI

Liu Sj, Liu Dl, Zhang Jq, Zeng Yj. Extraction of Fetal Electrocardiogram Using Recursive Least Squares and Normalized Least Mean Squares Algorithms. In: 2011 3rd International Conference on Advanced Computer Control. Harbin: IEEE; 2011. p. 333–336. 10.1109/ICACC.2011.6016426.

Alexander ST. Fast Transversal Filters. In: Adaptive Signal Processing. New York: Springer New York; 1986. p. 154–176. 10.1007/978-1-4612-4978-8_11.

Martinek R, Kahankova R, Jaros R, Barnova K, Matonia A, Jezewski M, et al. Non-Invasive Fetal Electrocardiogram Extraction Based on Novel Hybrid Method for Intrapartum ST Segment Analysis. IEEE Access Pract Innovations Open Solutions. 2021;9:28608–28631. doi: 10.1109/ACCESS.2021.3058733. DOI

Martinek R, Barnova K, Jaros R, Kahankova R, Kupka T, Jezewski M, et al. Passive Fetal Monitoring by Advanced Signal Processing Methods in Fetal Phonocardiography. IEEE Access Pract Innovations Open Solutions. 2020;8:221942–221962. doi: 10.1109/ACCESS.2020.3043496. DOI

Mhajna M, Sadeh B, Yagel S, Sohn C, Schwartz N, Warsof S, et al. A novel, cardiac-derived algorithm for uterine activity monitoring in a wearable remote device. Front Bioeng Biotechnol. 2022;10:1–19. doi: 10.3389/fbioe.2022.933612. PubMed DOI PMC

de Campos DA, Arulkumaran S. FIGO consensus guidelines on intrapartum fetal monitoring. Int J Gynecol Obstet. 2015;131(1):5–8. doi: 10.1016/j.ijgo.2015.06.018. PubMed DOI

Bergstra J, Bengio Y. Random search for hyper-parameter optimization. J Mach Learn Res. 2012;13(2):281–305.

Kennedy J, Eberhart R. Particle Swarm Optimization. In: Proceedings of ICNN’95 - International Conference on Neural Networks. vol. 4. Perth: IEEE; 1995. p. 1942–1948. 10.1109/ICNN.1995.488968.

Storn R, Price K. Differential Evolution - A Simple and Efficient Heuristic for global Optimization over Continuous Spaces. J Glob Optim. 1997;11(4):341–359. doi: 10.1023/A:1008202821328. DOI

Mirjalili S. Moth-Flame Optimization Algorithm: A Novel Nature-Inspired Heuristic Paradigm. Knowl-Based Syst. 2015;89:228–249. doi: 10.1016/j.knosys.2015.07.006. DOI

Nasiri M. Fetal Electrocardiogram Signal Extraction by ANFIS Trained with PSO Method. Int J Electr Comput Eng (IJECE). 2012;2(2):247–260. 10.11591/ijece.v2i2.231.

Elmansouri K, Latif R, Maoulainine F. Improvement of Fetal Electrocardiogram Extraction by Application of Fuzzy Adaptive Resonance Theory to Adaptive Neural Fuzzy System. Int J Innov Appl Stud. 2014;9(1):95.

Panigrahy D, Rakshit M, Sahu PK. An Efficient Method for Fetal ECG Extraction from Single Channel Abdominal ECG. In: 2015 International Conference on Industrial Instrumentation and Control (ICIC). Pune: IEEE; 2015. p. 1083–1088. 10.1109/IIC.2015.7150908.

Kockanat S, Kockanat S. Analysis and Extraction of Fetal Electrocardiogram Signal with Adaptive Filtering Using Differential Evolution Algorithm. Cumhuriyet Sci J. 2018;294–302. 10.17776/csj.407424.

Panigrahy D, Sahu PK. Extraction of Fetal ECG Signal by an Improved Method Using Extended Kalman Smoother Framework from Single Channel Abdominal ECG Signal. Australas Phys Eng Sci Med. 2017;40(1):191–207. doi: 10.1007/s13246-017-0527-5. PubMed DOI

Jibia MS, Jibia AU. Fetal Electrocardiogram Extraction Using Moth Flame Optimization (MFO)-Based Adaptive Filter. Adv Sci Technol Eng Syst J. 2021;6(2):303–312. 10.25046/aj060235.

Silwattananusarn T, Kanarkard W, Tuamsuk K. Enhanced Classification Accuracy for Cardiotocogram Data with Ensemble Feature Selection and Classifier Ensemble. J Comput Commun. 2016;04(04):20–35. doi: 10.4236/jcc.2016.44003. DOI

Subasi A, Kadasa B, Kremic E. Classification of the Cardiotocogram Data for Anticipation of Fetal Risks Using Bagging Ensemble Classifier. Procedia Comput Sci. 2020;168:34–39. doi: 10.1016/j.procs.2020.02.248. DOI

Krupa N, Ma M, Zahedi E, Ahmed S, Hassan FM. Antepartum Fetal Heart Rate Feature Extraction and Classification Using Empirical Mode Decomposition and Support Vector Machine. Biomed Eng Online. 2011;10(1):6. doi: 10.1186/1475-925X-10-6. PubMed DOI PMC

Carter EB, Tuuli MG, Caughey AB, Odibo AO, Macones GA, Cahill AG. Number of Prenatal Visits and Pregnancy Outcomes in Low-Risk Women. J Perinatol. 2016;36(3):178–181. doi: 10.1038/jp.2015.183. PubMed DOI PMC

Laranjo L, Dunn AG, Tong HL, Kocaballi AB, Chen J, Bashir R, et al. Conversational Agents in Healthcare: A Systematic Review. J Am Med Inform Assoc. 2018;25(9):1248–1258. doi: 10.1093/jamia/ocy072. PubMed DOI PMC

Mutabazi E, Ni J, Tang G, Cao W. A Review on Medical Textual Question Answering Systems Based on Deep Learning Approaches. Appl Sci. 2021;11(12):5456. doi: 10.3390/app11125456. DOI

Abdallah A, Kasem M, Hamada MA, Sdeek S. Automated Question-Answer Medical Model Based on Deep Learning Technology. In: Proceedings of the 6th International Conference on Engineering & MIS 2020. Almaty Kazakhstan: ACM; 2020. p. 1–8. 10.1145/3410352.3410744.

Nadarzynski T, Miles O, Cowie A, Ridge D. Acceptability of Artificial Intelligence (AI)-Led Chatbot Services in Healthcare: A Mixed-Methods Study. Digital Health. 2019;5:205520761987180. doi: 10.1177/2055207619871808. PubMed DOI PMC

Adamopoulou E, Moussiades L. Chatbots: History, Technology, and Applications. Mach Learn Appl. 2020;2:100006. doi: 10.1016/j.mlwa.2020.100006. DOI

Philip P, Micoulaud-Franchi JA, Sagaspe P, Sevin ED, Olive J, Bioulac S, et al. Virtual Human as a New Diagnostic Tool, a Proof of Concept Study in the Field of Major Depressive Disorders. Sci Rep. 2017;7(1):42656. doi: 10.1038/srep42656. PubMed DOI PMC

Lucas GM, Rizzo A, Gratch J, Scherer S, Stratou G, Boberg J, et al. Reporting Mental Health Symptoms: Breaking Down Barriers to Care with Virtual Human Interviewers. Front Robot AI. 2017;4:51. doi: 10.3389/frobt.2017.00051. DOI

Levin E, Levin A. Evaluation of Spoken Dialogue Technology for Real-Time Health Data Collection. J Med Internet Res. 2006;8(4):e30. doi: 10.2196/jmir.8.4.e30. PubMed DOI PMC

Giorgino T, Azzini I, Rognoni C, Quaglini S, Stefanelli M, Gretter R, et al. Automated Spoken Dialogue System for Hypertensive Patient Home Management. Int J Med Inform. 2005;74(2–4):159–167. doi: 10.1016/j.ijmedinf.2004.04.026. PubMed DOI

Azzini I, Falavigna D, Giorgino T, Gretter R, Quaglini S, Rognoni C, et al. Automated spoken dialog system for home care and data acquisition from chronic patients. In: The New Navigators: From Professionals to Patients. Amsterdam: IOS Press; 2003. p. 146–51. PubMed

Black LA, McTear M, Black N, Harper R, Lemon M. Appraisal of a Conversational Artefact and Its Utility in Remote Patient Monitoring. In: 18th IEEE Symposium on Computer-Based Medical Systems (CBMS’05). Dublin: IEEE; 2005. p. 506–508. 10.1109/CBMS.2005.33.

Harper R, Nicholl P, McTear M, Wallace J, Black LA, Kearney P. Automated Phone Capture of Diabetes Patients Readings with Consultant Monitoring via the Web. In: 15th Annual IEEE International Conference and Workshop on the Engineering of Computer Based Systems (Ecbs 2008). Belfast: IEEE; 2008. p. 219–226. 10.1109/ECBS.2008.31.

Griol D, Carbó J, Molina JM. An Automatic Dialog Simulation Technique to Develop and Evaluate Interactive Conversational Agents. Appl Artif Intell. 2013;27(9):759–780. doi: 10.1080/08839514.2013.835230. DOI

Battineni G, Chintalapudi N, Amenta F. AI Chatbot Design during an Epidemic like the Novel Coronavirus. Healthcare. 2020;8(2):154. doi: 10.3390/healthcare8020154. PubMed DOI PMC

Rodsawang C, Thongkliang P, Intawong T, Sonong A, Thitiwatthana Y, Chottanapund S. Designing a competent chatbot to counter the Covid-19 pandemic and empower risk communication in an emergency response system. OSIR J. 2020;13(2):71–77.

Dennis AR, Kim A, Rahimi M, Ayabakan S. User Reactions to COVID-19 Screening Chatbots from Reputable Providers. J Am Med Inform Assoc. 2020;27(11):1727–1731. doi: 10.1093/jamia/ocaa167. PubMed DOI PMC

Walwema J, The WHO. Health Alert: Communicating a Global Pandemic with WhatsApp. J Bus Tech Commun. 2021;35(1):35–40. doi: 10.1177/1050651920958507. DOI

Almalki M, Azeez F. Health Chatbots for Fighting COVID-19: A Scoping Review. Acta Inform Med. 2020;28(4):241. doi: 10.5455/aim.2020.28.241-247. PubMed DOI PMC

Chung K, Cho HY, Park JY. A Chatbot for Perinatal Women’s and Partners’ Obstetric and Mental Health Care: Development and Usability Evaluation Study. JMIR Med Inform. 2021;9(3):e18607. doi: 10.2196/18607. PubMed DOI PMC

Vaira L, Bochicchio MA, Conte M, Casaluci FM, Melpignano A. MamaBot: A System Based on ML and NLP for Supporting Women and Families during Pregnancy. In: Proceedings of the 22nd International Database Engineering & Applications Symposium on - IDEAS 2018. Villa San Giovanni: ACM Press; 2018. p. 273–277. 10.1145/3216122.3216173.

Marko KI, Ganju N, Krapf JM, Gaba ND, Brown JA, Benham JJ, et al. A Mobile Prenatal Care App to Reduce In-Person Visits: Prospective Controlled Trial. JMIR mHealth uHealth. 2019;7(5):e10520. doi: 10.2196/10520. PubMed DOI PMC

Lavariega JC, Córdova GA, Gómez LG, Avila A. Monitoring and Assisting Maternity-Infant Care in Rural Areas (Mamicare). In: E-Health and Telemedicine: Concepts, Methodologies, Tools, and Applications. Pennsylvania: IGI Global; 2016. p. 347–59.

Razaque A, Amsaad F, Jaro Khan M, Hariri S, Chen S, Siting C, et al. Survey: Cybersecurity Vulnerabilities, Attacks and Solutions in the Medical Domain. IEEE Access Pract Innovations Open Solutions. 2019;7:168774–168797. doi: 10.1109/ACCESS.2019.2950849. DOI

Independent component analysis algorithms for non-invasive fetal electrocardiography