Woodward, P. J., Kennedy, A. & Sohaey, R. Diagnostic Imaging: Obstetrics 4th edn (Elsevier, 2021).
Hutter, D., Kingdom, J. & Jaeggi, E. Causes and mechanisms of intrauterine hypoxia and its impact on the fetal cardiovascular system: a review. Int. J. Pediatr. 2010, 401323 (2010).
Google Scholar
Berkley, E., Chauhan, S. P. & Abuhamad, A. Doppler assessment of the fetus with intrauterine growth restriction. Am. J. Obstet. Gynecol. 206, 300–308 (2012).
Google Scholar
Nelson, K. B. & Grether, J. K. Causes of cerebral palsy. Curr. Opin. Pediatr. 11, 487–491 (1999).
Google Scholar
McClure, E. et al. Global Network for Women’s and Children’s Health Research: probable causes of stillbirth in low- and middle-income countries using a prospectively defined classification system. BJOG 125, 131–138 (2018).
Google Scholar
Smith, G. C. S. & Fretts, R. C. Stillbirth. Lancet 370, 1715–1725 (2007).
Google Scholar
Lawn, J. E. et al. Stillbirths: rates, risk factors, and acceleration towards 2030. Lancet 387, 587–603 (2016).
Google Scholar
Rouse, D. J. Antepartum fetal surveillance ACOG practice bulletin, number 229. Obstet. Gynecol. 137, E116–E127 (2021).
Google Scholar
Rouse, D. J., Owen, J., Goldenberg, R. L. & Cliver, S. P. Determinants of the optimal time in gestation to initiate antenatal fetal testing: a decision-analytic approach. Am. J. Obstet. Gynecol. 173, 1357–1363 (1995).
Google Scholar
Harkey, K. T., Casale, M. B., Pantelopoulos, A. A. & Zurcher, M. A. Assessing the clinical use of a novel, mobile fetal monitoring device. Obstet. Gynecol. 123, 55S (2014).
Google Scholar
Ryu, D. et al. Comprehensive pregnancy monitoring with a network of wireless, soft, and flexible sensors in high- and low-resource health settings. Proc. Natl Acad. Sci. USA 118, e2100466118 (2021).
Google Scholar
Freeman, R. K. Problems with intrapartum fetal heart rate monitoring interpretation and patient management. Obstet. Gynecol. 100, 813–826 (2002).
Google Scholar
Grivell, R. M., Alfirevic, Z., Gyte, G. M. & Devane, D. Antenatal cardiotocography for fetal assessment. Cochrane Database Syst. Rev. 9, CD007863 (2015).
Alfirevic, Z., Devane, D., Gyte, G. M. & Cuthbert, A. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database Syst. Rev. 2, CD006066 (2017).
Google Scholar
Marzbanrad, F., Stroux, L. & Clifford, G. D. Cardiotocography and beyond: a review of one-dimensional Doppler ultrasound application in fetal monitoring. Physiol. Meas. 39, 08TR01 (2018).
Google Scholar
Hayes-Gill, B. R. Monica Healthcare: from the research laboratory to commercial reality—a real-life case study. Healthc. Technol. Lett. 8, 1–10 (2021).
Google Scholar
Gunther, J. E., Jayet, B., Sekar, S. K. V., Kainerstorfer, J. M. & Andersson-Engels, S. Review of optical methods for fetal monitoring in utero. J. Biophotonics 15, e202100343 (2022).
Google Scholar
Du, Y.-C., Yen, L. B., Kuo, P.-L. & Tsai, P.-Y. A wearable device for evaluation of relative position, force, and duration of fetal movement for pregnant woman care. IEEE Sens. J. 21, 19341–19350 (2021).
Google Scholar
Nicolaides, K., Rizzo, G., Hecher, K. & Ximenes, R. Doppler in Obstetrics (The Fetal Medicine Foundation, 2002).
Salomon, L. J. et al. ISUOG Practice Guidelines: ultrasound assessment of fetal biometry and growth. Ultrasound Obstet. Gynecol. 53, 715–723 (2019).
Google Scholar
Bhide, A. et al. ISUOG Practice Guidelines (updated): use of Doppler velocimetry in obstetrics. Ultrasound Obstet. Gynecol. 58, 331–339 (2021).
Google Scholar
Oros, D. et al. Reference ranges for Doppler indices of umbilical and fetal middle cerebral arteries and cerebroplacental ratio: systematic review. Ultrasound Obstet. Gynecol. 53, 454–464 (2019).
Google Scholar
Drukker, L. et al. International gestational age-specific centiles for umbilical artery Doppler indices: a longitudinal prospective cohort study of the INTERGROWTH-21st Project. Am. J. Obstet. Gynecol. 222, 602.e1–602.e15 (2020).
Google Scholar
Kiserud, T. et al. The World Health Organization fetal growth charts: a multinational longitudinal study of ultrasound biometric measurements and estimated fetal weight. PLOS Med. 14, e1002220 (2017).
Google Scholar
Papageorghiou, A. T. et al. International standards for fetal growth based on serial ultrasound measurements: the fetal growth longitudinal study of the INTERGROWTH-21st Project. Lancet 384, 869–879 (2014).
Google Scholar
Goldenberg, R. L., Harrison, M. S. & McClure, E. M. Stillbirths: the hidden birth asphyxia—US and global perspectives. Clin. Perinatol. 43, 439–453 (2016).
Google Scholar
AIUM practice parameter for the performance of standard diagnostic obstetric ultrasound. J. Ultrasound Med. 43, E20–E32 (2024).
Wang, C. et al. Bioadhesive ultrasound for long-term continuous imaging of diverse organs. Science 377, 517–523 (2022).
Google Scholar
Hu, H. et al. A wearable cardiac ultrasound imager. Nature 613, 667–675 (2023).
Google Scholar
Du, W. et al. Conformable ultrasound breast patch for deep tissue scanning and imaging. Sci. Adv. 9, eadh5325 (2023).
Google Scholar
Zhang, L. et al. A conformable phased-array ultrasound patch for bladder volume monitoring. Nat. Electron. 7, 77–90 (2023).
Google Scholar
Khalil, A. et al. ISUOG Practice Guidelines: performance of third-trimester obstetric ultrasound scan. Ultrasound Obstet. Gynecol. 63, 131–147 (2024).
Google Scholar
Hoskins, P. R., Martin, K. & Thrush, A. (eds) Diagnostic Ultrasound Physics and Equipment (CRC Press, 2019).
Evans, D. H., Jensen, J. A. & Nielsen, M. B. Ultrasonic colour Doppler imaging. Interface Focus 1, 490–502 (2011).
Google Scholar
Zhang, L., Du, W., Kim, J.-H., Yu, C.-C. & Dagdeviren, C. An emerging era: conformable ultrasound electronics. Adv. Mater. 36, e2307664 (2024).
Google Scholar
Aksoy, B. et al. Shielded soft force sensors. Nat. Commun. 13, 4649 (2022).
Google Scholar
Institute of Physics and Engineering in Medicine. IPEM Report 102—Quality Assurance of Ultrasound Imaging Systems. (IPEM, 2010).
Thijssen, J. M., van Wijk, M. C. & Cuypers, M. H. M. Performance testing of medical echo/Doppler equipment. Eur. J. Ultrasound 15, 151–164 (2002).
Google Scholar
Browne, J. E. A review of Doppler ultrasound quality assurance protocols and test devices. Physica Medica 30, 742–751 (2014).
Google Scholar
Ter Haar, G. (ed.) The Safe Use of Ultrasound in Medical Diagnosis (The British Institute of Radiology, 2012).
AIUM official statement for recommended maximum scanning times for displayed thermal index values. J. Ultrasound Med. 42, E74–E75 (2023).
Safety Group of the British Medical Ultrasound Society. Guidelines for the Safe Use of Diagnostic Ultrasound Equipment. (BMUS, 2010).
Food and Drug Administration. Marketing Clearance of Diagnostic Ultrasound Systems and Transducers: Guidance for Industry and Food and Drug Administration Staff. Report No. FDA-2017-D-5372 (FDA, 2023).
Hekkenberg, R. T. & Bezemer, R. A. Aspects Concerning the Measurement of Surface Temperature of Ultrasonic Diagnostic Transducers, Part 2: On a Human and Artificial Tissue. (TNO Preventie en Gezondheid, 2003).
International Electrotechnical Commission. Ultrasonics: Field Characterization—Test Methods for the Determination of Thermal and Mechanical Indices Related to Medical Diagnostic Ultrasonic Fields. Report No. IEC 62359:2010/AMD1:2017 (IEC, 2017).
Maulik, D. & Lees, C. C. (eds) Doppler Ultrasound in Obstetrics and Gynecology (Springer, 2023).
Conde-Agudelo, A., Villar, J., Kennedy, S. H. & Papageorghiou, A. T. Predictive accuracy of cerebroplacental ratio for adverse perinatal and neurodevelopmental outcomes in suspected fetal growth restriction: systematic review and meta-analysis. Ultrasound Obstet. Gynecol. 52, 430–441 (2018).
Google Scholar
Hadlock, F. P., Harrist, R. B., Sharman, R. S., Deter, R. L. & Park, S. K. Estimation of fetal weight with the use of head, body, and femur measurements—a prospective study. Am. J. Obstet. Gynecol. 151, 333–337 (1985).
Google Scholar
Zhou, S. et al. Transcranial volumetric imaging using a conformal ultrasound patch. Nature 629, 810–818 (2024).
Google Scholar
Oates, C. Ultrasound Technology for Clinical Practitioners (Wiley, 2023).
Ali, S. et al. Prognostic accuracy of antenatal Doppler ultrasound for adverse perinatal outcomes in low-income and middle-income countries: a systematic review. BMJ Open 11, e049799 (2021).
Google Scholar
Ali, S. et al. Standardization and quality control of Doppler and fetal biometric ultrasound measurements in low-income setting. Ultrasound Obstet. Gynecol. 61, 481–487 (2023).
Google Scholar
Demi, L. Practical guide to ultrasound beam forming: beam pattern and image reconstruction analysis. Appl. Sci. 8, 1544 (2018).
Google Scholar
Ronneberger, O., Fischer, P. & Brox, T. U-Net: convolutional networks for biomedical image segmentation. In Proceedings of the Medical Image Computing and Computer-Assisted Intervention (eds Navab, N., Hornegger, J., Wells, W. M. & Frangi, A. F.) (Springer, 2015).
Shi, X. et al. Convolutional LSTM network: a machine learning approach for precipitation nowcasting. In Proceedings of the 29th International Conference on Neural Information Processing Systems (eds Cortes, C., Lee, D. D., Sugiyama, M. & Garnett, R.) (ACM, 2015).
Alfirevic, Z., Stampalija, T. & Dowswell, T. Fetal and umbilical Doppler ultrasound in high-risk pregnancies. Cochrane Database Syst. Rev. 6, CD007529 (2017).
Google Scholar
Lees, C. C. et al. ISUOG Practice Guidelines: diagnosis and management of small-for-gestational-age fetus and fetal growth restriction. Ultrasound Obstet. Gynecol. 56, 298–312 (2020).
Google Scholar
Sotiriadis, A. et al. ISUOG Practice Guidelines: role of ultrasound in screening for and follow-up of pre-eclampsia. Ultrasound Obstet. Gynecol. 53, 7–22 (2019).
Google Scholar
Vogel, J. P. et al. The global epidemiology of preterm birth. Best Pract. Res. Clin. Obstet. Gynaecol. 52, 3–12 (2018).
Google Scholar
Gardosi, J., Madurasinghe, V., Williams, M., Malik, A. & Francis, A. Maternal and fetal risk factors for stillbirth: population based study. BMJ 346, f108 (2013).
Google Scholar
Freeman, R. K., Garite, T. J., Nageotte, M. P. & Miller, L. A. Fetal Heart Rate Monitoring 4th edn (Lippincott Williams & Wilkins, 2012).
Pildner Von Steinburg, S. et al. What is the ‘normal’ fetal heart rate? PeerJ 1, e82 (2013).
Google Scholar
Chang, L. W., Hsu, K. H. & Li, P. C. Graphics processing unit-based high-frame-rate color doppler ultrasound processing. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 56, 1856–1860 (2009).
Google Scholar
So, H., Chen, J., Yiu, B. & Yu, A. Medical ultrasound imaging: to GPU or not to GPU? IEEE Micro 31, 54–65 (2011).
Google Scholar
Lee, W. et al. Universal assembly of liquid metal particles in polymers enables elastic printed circuit board. Science 378, 637–641 (2022).
Google Scholar
You, I. et al. Artificial multimodal receptors based on ion relaxation dynamics. Science 370, 961–965 (2020).
Google Scholar
Wang, S. et al. Skin electronics from scalable fabrication of an intrinsically stretchable transistor array. Nature 555, 83–88 (2018).
Google Scholar
Son, D. et al. Multifunctional wearable devices for diagnosis and therapy of movement disorders. Nat. Nanotechnol. 9, 397–404 (2014).
Google Scholar
Liu, Z. et al. A three-dimensionally architected electronic skin mimicking human mechanosensation. Science 384, 987–994 (2024).
Google Scholar
Lin, M. et al. A fully integrated wearable ultrasound system to monitor deep tissues in moving subjects. Nat. Biotechnol. 42, 448–457 (2024).
Google Scholar
Skow, R. J. et al. Effects of prenatal exercise on fetal heart rate, umbilical and uterine blood flow: a systematic review and meta-analysis. Br. J. Sports Med. 53, 124–133 (2019).
Google Scholar
Georgieva, A., Abry, P., Nunes, I. & Frasch, M. G. Editorial: Fetal–maternal monitoring in the age of artificial intelligence and computer-aided decision support: a multidisciplinary perspective. Front. Pediatr. 10, 2296–2360 (2022).
Google Scholar
Huang, Z. et al. Three-dimensional integrated stretchable electronics. Nat. Electron. 1, 473–480 (2018).
Google Scholar
Kempski, K. M., Graham, M. T., Gubbi, M. R., Palmer, T. & Lediju Bell, M. A. Application of the generalized contrast-to-noise ratio to assess photoacoustic image quality. Biomed. Opt. Express 11, 3684–3698 (2020).
Google Scholar
Wear, K. A. & Shah, A. Nominal versus actual spatial resolution: comparison of directivity and frequency-dependent effective sensitive element size for membrane, needle, capsule, and fiber-optic hydrophones. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 70, 112–119 (2023).
Google Scholar
Harris, G. R. et al. Hydrophone measurements for biomedical ultrasound applications: a review. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 70, 85–100 (2023).
Google Scholar
Wear, K. A., Gammell, P. M., Maruvada, S., Liu, Y. & Harris, G. R. Improved measurement of acoustic output using complex deconvolution of hydrophone sensitivity. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 61, 62–75 (2014).
Google Scholar
Wear, K. A. Hydrophone spatial averaging correction for acoustic exposure measurements from arrays—part I: theory and impact on diagnostic safety indexes. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 68, 358–375 (2021).
Google Scholar
Szabo, T. L. Diagnostic Ultrasound Imaging: Inside Out 2nd edn (Academic Press, 2014).
International Electrotechnical Commission. Medical Electrical Equipment—Part 2–37: Particular Requirements for the Basic Safety and Essential Performance of Ultrasonic Medical Diagnostic and Monitoring Equipment. Report No. IEC 60601-2-37:2024 (IEC, 2024).
Kennedy, A. M. & Woodward, P. J. A radiologist’s guide to the performance and interpretation of obstetric Doppler US. Radiographics 39, 893–910 (2019).
Google Scholar