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Cited by 105Non-Invasive Vital Sign MonitoringAdvanced Sensor and Energy Harvesting MaterialsWireless Body Area Networks

Comprehensive pregnancy monitoring with a network of wireless, soft, and flexible sensors in high- and low-resource health settings

Open access
Ryu, Dennis, Kim, Dong Hyun, Price, Joan T., Lee, Jong Yoon, Chung, Ha Uk, Allen, Emily, Walter, Jessica R., Jeong, Hyoyoung +24 more·2021·Proceedings of the National Academy of Sciences
DOI 10.1073/pnas.2100466118PMC PMC8157941
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Abstract

Significance: Monitoring vital signs for laboring women and their fetuses is foundational to the delivery of obstetrical care; however, monitoring platforms for pregnancy have undergone little innovation over the last several decades with many low-income settings lacking basic access. We report a new time-synchronized, flexible, and wireless sensor system applicable across the entire continuum of antepartum and postpartum care that provides continuous, comprehensive, and noninvasive monitoring (heart rate, respiratory rate, and pulse oxygenation) compatible with a wide range of mobile devices. This system offers advanced features such as continuous blood pressure, uterine electrohysterography, and automated body position classification. We further demonstrate the performance of this new system among pregnant individuals ( n = 576) in both high-resource settings and low-resource care settings.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper reports a time-synchronized, wireless, soft, flexible sensor network for comprehensive maternal–fetal pregnancy monitoring across antepartum and postpartum care. It was tested in 576 pregnant individuals in high-resource Chicago and low-resource Lusaka, with comparisons against gold-standard monitors for vital signs, fetal heart rate, uterine contraction, and continuous blood pressure surrogates.

Key findings

  • The system uses chest, limb, and abdominal sensors: chest and limb sensors operate for 24 h, the abdominal sensor for 8 h; the three sensors are time-synchronized with 1-ms timing accuracy and an SD of 3.6 ms over 24 consecutive hours.
  • In 13 healthy nonpregnant adults, compared with a Philips Intellivue MP50, mean differences were −0.09 bpm for HR (SD 0.95 bpm), −0.19% for SpO2 (SD 1.68%), and −0.45 breaths per minute for RR (SD 1.64 breaths per minute), within FDA guidelines for new cardiopulmonary monitoring platforms.
  • Fetal heart rate from the abdominal sensor compared with gold-standard Doppler in n = 10 laboring women across 3,213 single data points had a mean difference of 0.1 bpm (SD 1 bpm).
  • In the total cohort of 576 pregnant people, 91 (16%) were recruited in Chicago using all three sensors and 485 (84%) in Lusaka using maternal sensors only; more than 85% of surveyed laboring people (41 of 48 respondents) and all 10 surveyed obstetrical providers reported a positive or very positive experience.

Methods

  • Design and sample: field trials/validation among pregnant women at 25–41 wk gestation (n = 576), including 91 at Prentice Women’s Hospital in Chicago (59 nonstress testing, 32 active labor) and 485 in Lusaka, Zambia, as part of the LABOR study; additional validation included n = 13 healthy nonpregnant adults, n = 10 laboring women for FHR, and n = 3 healthy subjects for cold-pressor BP testing.
  • Sensor construction: four-layer flexible printed circuit boards for chest and limb sensors, two-layer for the abdominal sensor, packaged in silicone; chest sensor measures ECG, SCG, chest-wall movement for RR, and skin temperature; limb sensor measures PPG and skin temperature; abdominal sensor measures Doppler ultrasound, EHG, and ECG.
  • Analysis: real-time algorithms on mobile devices derived HR, SpO2, RR, temperature, FHR, uterine contraction, PAT-based BP, and body position; Bland–Altman comparisons were made against gold-standard systems; body position was classified using a Gaussian mixture model with n = 8 clusters merged into four postures; time-series heat maps were generated for HR, RR, SpO2, and derived SBP in the low-resource cohort (n = 485).

Limitations

  • The paper states that PAT-based BP measurements still require initial calibration with a gold-standard BP device, and this calibration step leads to further errors; further work is needed to validate PAT-based measurements for elevated BP following established guidelines with at least n = 85 subjects before wider clinical use.
  • The paper states that further development efforts are targeting enhancement of fetal ECG capabilities of the system.
  • Evident from the text: the low-resource cohort of 485 pregnant people in Lusaka used maternal sensors only (chest and limb), so fetal monitoring with the abdominal sensor was not validated in that setting; the abdominal sensor also has a shorter operation time (8 h) than the chest and limb sensors (24 h).

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1073/pnas.2100466118

Cites

56 of 56 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 52 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    The abdominal sensor is capable of detecting uterine contractions during labor.

    “We demonstrate the sensor’s capability of detecting uterine contractions during labor.”
    Quote in the paperSubstantial claim
  • Findingown data

    In a cohort of 13 healthy nonpregnant adults, the experimental system and a commercially available gold-standard monitoring system (Intellivue MP50; Philips) showed agreement in heart rate, SpO2, and respiratory rate calculations.

    “In Fig. 2 D–F we demonstrate the agreement in HR, SpO2, and RR calculations between the experimental system and a commercially available gold-standard monitoring system (Intellivue MP50; Philips) operating concomitantly in a cohort of 13 healthy nonpregnant adults.”
    Quote in the paperSubstantial claim
  • Findingown data

    The abdominal sensor is capable of capturing incidental fetal ECG, which coincides with fetal Doppler signal.

    “Although intended for measuring maternal ECG, maternal HR, and uterine contraction, the abdominal sensor is also capable of capturing incidental fetal ECG, which coincides with fetal Doppler signal.”
    Quote in the paperNot a substantial claim
  • Findingown data

    An additional 485 (84%) pregnant people were recruited in Lusaka, Zambia using the maternal sensors only (chest and limb).

    “An additional 485 (84%) pregnant people were recruited in Lusaka, Zambia using the maternal sensors only (chest and limb).”
    Quote in the paperSubstantial claim
  • Findingown data

    The system's performance was demonstrated among pregnant individuals (n = 576) in both high-resource and low-resource care settings.

    “We further demonstrate the performance of this new system among pregnant individuals (n = 576) in both high-resource settings and low-resource care settings.”
    Quote in the paperSubstantial claim
  • May combine two claims. 38
  • Classified as probably not a substantial claim. 17
  • The quote only partly states this claim. 1

  • May combine two claims.

    Findingown data

    The mean difference between the experimental system and gold standard was −0.09 beats per minute for heart rate (SD 0.95 bpm), −0.19% for SpO2 (SD 1.68%), and −0.45 breaths per minute for respiratory rate (SD 1.64 breaths per minute).

    “The mean difference is −0.09 beats per minute (bpm) for HR (SD 0.95 bpm), −0.19% for SpO2 (SD 1.68%), and −0.45 breaths per minute for RR (SD 1.64 breaths per minute).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given

    The chest and limb sensors have an operation time of 24 h and the abdominal sensor has an operation time of 8 h.

    “The chest and limb sensors have an operation time of 24 h and the abdominal sensor has an operation time of 8 h.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In a subset of people, the R-to-R peak interval for maternal ECG averaged 635 ms, and the fetal ECG R-to-R peak interval averaged 344 ms.

    “In a subset of people the abdominal sensor output was analyzed to isolate fetal ECG; the R-to-R peak interval for maternal ECG averaged 635 ms, and the fetal ECG R-to-R peak interval averaged 344 ms.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The final cohort recruited in the pilot study included a wide range of maternal ages (18 to 43 y), races and ethnicities, and gestational ages (25 to 41 wk).

    “The final cohort recruited in the pilot study included a wide range of maternal ages (18 to 43 y), races and ethnicities, and gestational ages (25 to 41 wk) (SI Appendix, Table S1).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    The new sensor system is time-synchronized, flexible, and wireless; applicable across the entire continuum of antepartum and postpartum care; provides continuous, comprehensive, and noninvasive monitoring of heart rate, respiratory rate, and pulse oxygenation; and is compatible with a wide range of mobile devices.

    “We report a new time-synchronized, flexible, and wireless sensor system applicable across the entire continuum of antepartum and postpartum care that provides continuous, comprehensive, and noninvasive monitoring (heart rate, respiratory rate, and pulse oxygenation) compatible with a wide range of mobile devices.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The abdominal sensor offers onboard wireless Doppler ultrasound, electrohysterography, and ECG.

    “The abdominal sensor (Fig. 1C) offers an onboard wireless Doppler ultrasound (US), EHG, and ECG, each sampled at 504 and 500 Hz, respectively.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    The chest sensor measures ECG, seismocardiogram, chest wall movement for respiratory rate, and skin temperature.

    “The chest sensor (Fig. 1A) measures ECG, seismocardiogram (SCG), chest wall movement for respiratory rate (RR), and skin temperature, each sampled at 512, 416, 52, and 0.2 Hz, respectively.”
    Quote in the paperNot a substantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingown data

    In a subset of n = 10 laboring women who contributed 3,213 single data points, the mean difference in fetal heart rate between the abdominal sensor and gold-standard Doppler ultrasound systems was 0.1 bpm with an SD of 1 bpm, showing strong agreement.

    “A Bland–Altman plot comparing data from the abdominal sensor to the gold standard is presented in Fig. 3C for a subset of n = 10 laboring women who contributed 3,213 single data points.”
    • Also stated in: § FHR and Uterine Contraction via a Soft, Flexible, and Wireless Abdominal Sensor. · boosted
      “The mean difference is 0.1 bpm with an SD of 1 bpm, showing strong agreement.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    The system offers continuous blood pressure, uterine electrohysterography, and automated body position classification.

    “This system offers advanced features such as continuous blood pressure, uterine electrohysterography, and automated body position classification.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Findingnone given

    The sensor is able to obtain high signal quality even in the presence of motion and is water-resistant such that it can be worn in the shower.

    “The sensor is able to obtain high signal quality even in the presence of motion and is water-resistant such that it can be worn in the shower.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning

    The chest and abdominal sensors communicate, enabling maternal ECG elimination from the abdominal sensor's outputs and allowing for fetal ECG isolation.

    “The chest and abdominal sensors also communicate, which enables maternal ECG elimination from the abdominal sensor’s outputs, allowing for fetal ECG isolation.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    The limb sensor measures photoplethysmogram and skin temperature.

    “The limb sensor (Fig. 1B) measures photoplethysmogram (PPG) and skin temperature, sampled at 256 and 0.2 Hz, respectively.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    The authors' data show cold-pressor-induced hypertensive episodes.

    “While our data show cold-pressor-induced hypertensive episodes”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The method has a high degree of agreement with traditional sphygmomanometers, capturing blood pressure at discrete time points with average errors less than 10 mmHg.

    “In Fig. 4A we demonstrate a high degree of agreement with traditional sphygmomanometers, capturing BP at discrete time points with average errors less than 10 mmHg.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The Bland-Altman plot demonstrates the accuracy of the method, which has a mean difference from the sphygmomanometer of 0.4 mmHg (SD 7.8 mmHg).

    “A Bland–Altman plot in Fig. 4B demonstrates the accuracy of our method, which has a mean difference from the sphygmomanometer of 0.4 mmHg (SD 7.8 mmHg).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In n = 3 healthy normal subjects with cold-pressor-induced variable blood pressure, PAT-based blood pressure measurement had an average mean error of 0.6 mmHg and root mean square error of 5.31 mmHg for systolic blood pressure, and an average mean error of 0.2 mmHg and root mean square error of 7.07 mmHg for diastolic blood pressure.

    “Our demonstration here in n = 3 healthy normal subjects in highly controlled settings with variable BP achieved via the cold-pressor method shows an average mean and root mean square error of 0.6 and 5.31 mmHg for SBP and 0.2 and 7.07 mmHg for diastolic BP”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    The authors present a wireless monitoring platform that provides comprehensive assessment of both the mother and fetus with compatibility across a wide range of mobile devices.

    “We present a wireless monitoring platform that provides comprehensive assessment of both the mother and fetus with compatibility across a wide range of mobile devices.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    The system is able to provide continuous body positioning categorization and continuous blood pressure assessments and has been deployed in a significant number of pregnant women.

    “This system is able to provide continuous body positioning categorization and continuous BP assessments and has been deployed in a significant number of pregnant women.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    The system offers comprehensive and advanced measurement modalities with evidence of feasibility, performance, and user-preference acceptability among laboring women in both high-resource and low-resource settings for both in-hospital and remote monitoring applications.

    “The system we present here offers comprehensive and advanced measurement modalities with evidence of feasibility, performance, and user-preference acceptability among laboring women in both high-resource and low-resource settings for both in-hospital and remote monitoring applications.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: In both high- and low-resource settings the burden placed on clinical staff in order to obtain physiologic information on a woman and her fetus is significant.

  • Classified as probably not a substantial claim.

    Findingnone given

    The system can be configured so as to alert providers only when thresholds of vital signs that are indicative of concern are crossed.

    “The system provided here can be configured so as to alert providers only when thresholds of vital signs that are indicative of concern are crossed.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    The system provides objective and real-time data outputs on the impact of maternal body position on both maternal and fetal health with the ability to assess how position may be associated with clinical outcomes and the potential to include automated alerts.

    “The system we present here provides objective and real-time data outputs on the impact of maternal body position on both maternal and fetal health with the ability to assess how position may be associated with clinical outcomes and the potential to include automated alerts to patients and providers for body position changes if indicated.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Research on the effects and benefits of laboring positions has been largely limited because of inability to monitor and collect data in clinical settings with fidelity.

  • May combine two claims.

    Findingnone given

    The consumables of the system are low-cost and consist of only single-use hydrogel adhesives and latex-free fabric strap (estimated <$0.25 per use).

    “The consumables of the system are also low-cost and consist of only single-use hydrogel adhesives and latex-free fabric strap (estimated <$0.25 per use).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    The sensors themselves are low-cost (estimated <$40 per sensor at large-scale manufacturing) and fully reusable after a wireless recharge and simple cleaning procedure.

    “First, the sensors themselves are low-cost (estimated <$40 per sensor at large-scale manufacturing) and fully reusable after a wireless recharge and simple cleaning procedure.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The Invu reports both fetal heart rate and maternal heart rate but does not capture uterine contractions.

    “The Invu reports both FHR and maternal HR but does not capture uterine contractions (15).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [15] M. Mhajna., Wireless, remote solution for home fetal and maternal heart rate monitoring. Am. J. Obstet. Gynecol. MFM 2, 100101 (2020). 33345967 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Study design and conductnone given

    The adhesive's adhesion strength has been deemed safe to use by a board-certified dermatologist.

    “A biocompatible, double-sided hydrogel adhesive conducts the signal from the patient to the chest and abdominal sensors and its adhesion strength has been deemed safe to use by a board-certified dermatologist.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Additional monitoring equipment designed to assess maternal or fetal status, such as pulse oximetry, blood pressure monitors, and electrocardiography, are typically used in a noncontinuous manner and place a relatively high burden on providers.

    “Additional monitoring equipment designed to assess maternal or fetal status, such as pulse oximetry, blood pressure (BP) monitors, and electrocardiography (ECG), are typically used in a noncontinuous manner and place a relatively high burden on providers (11).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [11] A. A. Boatin., Wireless vital sign monitoring in pregnant women: A functionality and acceptability study. Telemed. J. E Health 22, 564– 571 (2016). 27172448 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The most common causes of maternal morbidity and mortality-hemorrhage, hypertensive disorders, infection, and sepsis-are often preceded by predictable vital signs perturbations in both high-resource and low-resource settings, and early intervention is key to improving outcomes.

    “The most common causes of maternal morbidity and mortality—hemorrhage, hypertensive disorders, infection, and sepsis—are often preceded by predictable vital signs perturbations in both high-resource and low-resource settings, and early intervention is key to improving outcomes (4–9).”
    Quote in the paperSubstantial claim0 of 6 sources checked
    • cites [4] R. W. Rochat, L. M. Koonin, H. K. Atrash, J. F. Jewett, Maternal mortality in the United States: Report from the maternal mortality collaborative. Obstet. Gynecol. 72, 91– 97 (1988). 3380512

      Not checked in the free run.

    • cites [5] B. Kodio., Levels and causes of maternal mortality in Senegal. Trop. Med. Int. Health 7, 499– 505 (2002). 12031071 source

      Not checked in the free run.

    • cites [6] M. E. D’Alton., Putting the “M” back in maternal-fetal medicine: A 5-year report card on a collaborative effort to address maternal morbidity and mortality in the United States. Am. J. Obstet. Gynecol. 221, 311– 317.e1 (2019). 30849353 PMC6728226 source

      Not checked in the free run.

    • cites [7] V. Filippi, D. Chou, C. Ronsmans, W. Graham, L. Say, “ Levels and causes of maternal mortality and morbidity” in Reproductive, Maternal, Newborn, and Child Health: Disease Control Priorities, R. E. Black, R. Laxminarayan, M. Temmerman, N. Walker, Eds. (International Bank for Reconstruction and Development/The World Bank, Washington, DC, ed. 3, 2016), vol. 2, pp. 51– 70. source

      Not checked in the free run.

    • cites [8] K. Nagaya., Causes of maternal mortality in Japan. JAMA 283, 2661– 2667 (2000). 10819948 source

      Not checked in the free run.

    • cites [9] N. Vousden, H. L. Nathan, A. H. Shennan, Innovations in vital signs measurement for the detection of hypertension and shock in pregnancy. Reprod. Health 15 (suppl. 1), 92 (2018). 29945641 PMC6020004 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The Bloomlife Pregnancy Tracker captures electrohysterography without fetal ECG.

    “The Bloomlife Pregnancy Tracker captures electrohysterography (EHG) without fetal ECG (16).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [16] M. Altini., 785: Early labour detection in laboratory and free-living conditions using combined electrohysterography and heart rate data. Am. J. Obstet. Gynecol. 220, S513– S514 (2019). source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The time synchronization infrastructure was previously established and yields an SD of 3.6 ms over 24 consecutive hours.

    “The time synchronization infrastructure was previously established and yields an SD of 3.6 ms over 24 consecutive hours (22).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [22] H. U. Chung., Skin-interfaced biosensors for advanced wireless physiological monitoring in neonatal and pediatric intensive-care units. Nat. Med. 26, 418– 429 (2020). 32161411 PMC7315772 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    The R-to-R peak intervals translate to 94 bpm and 170 bpm for maternal and fetal heart rate, respectively.

    “The R-to-R peak intervals translate to 94 bpm and 170 bpm for maternal and fetal HR, respectively.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    All participants provided written informed consent with research protocols approved by the Institutional Review Boards of Northwestern University (STU00205895) and the University of North Carolina (19-0765).

    “All participants provided written informed consent with research protocols approved by the Institutional Review Boards of Northwestern University (STU00205895) and the University of North Carolina (19-0765).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The Novii Wireless Patch System can acquire fetal ECG but cannot monitor nonsingleton pregnancies and is limited to term pregnancies (at least 37 wk of gestation).

    “Other systems, such as the Novii Wireless Patch System from Monica Healthcare, are available to acquire fetal ECG, but such systems alone cannot monitor nonsingleton pregnancies and are limited to term pregnancies (at least 37 wk of gestation) (17).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [17] A. Wacker-Gussmann., Fetal cardiac time intervals in healthy pregnancies–An observational study by fetal ECG (Monica Healthcare System). J. Perinat. Med. 46, 587– 592 (2018). 28453441 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Altering maternal positioning during labor as a means of fetal resuscitation is common.

    “Altering maternal positioning during labor as a means of fetal resuscitation is common (38–40).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [38] P. R. Stone.; Maternal Sleep in Pregnancy Research Group, The University of Auckland, Effect of maternal position on fetal behavioural state and heart rate variability in healthy late gestation pregnancy. J. Physiol. 595, 1213– 1221 (2017). 27871127 PMC5309385 source

      Not checked in the free run.

    • cites [39] G. Cito., Maternal position during non-stress test and fetal heart rate patterns. Acta Obstet. Gynecol. Scand. 84, 335– 338 (2005). 15762962 source

      Not checked in the free run.

    • cites [40] B. Carbonne, A. Benachi, M. L. Lévèque, D. Cabrol, E. Papiernik, Maternal position during labor: Effects on fetal oxygen saturation measured by pulse oximetry. Obstet. Gynecol. 88, 797– 800 (1996). 8885916 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Use of newer fetal ECG systems in multiple-gestation or preterm fetuses has not been validated extensively and would be considered off-label.

    “Use of these newer systems in multiple-gestation or preterm fetuses have not been validated extensively and would be considered off-label if used in these clinical scenarios.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [17] A. Wacker-Gussmann., Fetal cardiac time intervals in healthy pregnancies–An observational study by fetal ECG (Monica Healthcare System). J. Perinat. Med. 46, 587– 592 (2018). 28453441 source

      Not checked in the free run.

    • cites [36] R. Sameni, G. D. Clifford, A review of fetal ECG signal processing; issues and promising directions. Open Pacing Electrophysiol. Ther. J. 3, 4– 20 (2010). 21614148 PMC3100207

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    The use of Doppler in the abdominal sensors allows the system to potentially monitor nonsingleton pregnancies with multiple patches.

    “The use of Doppler in our abdominal sensors allows the system to potentially monitor nonsingleton pregnancies with multiple patches.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Some studies suggest upright postures have been associated with shorter early labor stages, a trend toward fewer cesarean deliveries, and less use of analgesia.

    “Some studies suggest upright postures have been associated with shorter early labor stages, a trend toward fewer cesarean deliveries, and less use of analgesia (41).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [41] J. K. Gupta, A. Sood, G. J. Hofmeyr, J. P. Vogel, Position in the second stage of labour for women without epidural anaesthesia. Cochrane Database Syst. Rev. 5, CD002006 (2017). 28539008 PMC6484432

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The supine position is often avoided given worse uteroplacental perfusion because of maternal hypotension and prolonged labor.

    “The supine position is often avoided given worse uteroplacental perfusion because of maternal hypotension (42) and prolonged labor (43).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [42] S. M. Kinsella, A. Lee, J. A. Spencer, Maternal and fetal effects of the supine and pelvic tilt positions in late pregnancy. Eur. J. Obstet. Gynecol. Reprod. Biol. 36, 11– 17 (1990). 2365116 source

      Not checked in the free run.

    • cites [43] A. Lawrence, L. Lewis, G. J. Hofmeyr, C. Styles, Maternal positions and mobility during first stage labour. Cochrane Database Syst. Rev., CD003934 (2013). PMC11664456 24105444

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    Previous research has demonstrated maternal position impacts maternal blood flow, labor progression, and patient comfort.

    “Previous research efforts have also demonstrated maternal position impacts maternal blood flow, labor progression, and patient comfort (44–46).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [44] O. Moraloglu., The influence of different maternal pushing positions on birth outcomes at the second stage of labor in nulliparous women. J. Matern. Fetal Neonatal Med. 30, 245– 249 (2017). 27028537 source

      Not checked in the free run.

    • cites [45] M. J. Guittier, V. Othenin-Girard, [Correcting occiput posterior position during labor: The role of maternal positions]. Gynécol. Obstét. Fertil. 40, 255– 260 (2012). 22099975 source

      Not checked in the free run.

    • cites [46] J. Roberts, L. Malasanos, C. Mendez-Bauer, Maternal positions in labor: Analysis in relation to comfort and efficiency. Birth Defects Orig. Artic. Ser. 17, 97– 128 (1981). 7326378

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    The ability to track body position continuously and concurrently with maternal and fetal vital signs offers an opportunity for improved monitoring and the ability to manage labor by modifying maternal body position as clinically indicated.

    “The ability to track body position continuously and concurrently with maternal and fetal vital signs offers an opportunity for improved monitoring and the ability to manage labor by modifying maternal body position as clinically indicated (37).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [37] G. J. Hofmeyr., Obstetric care in low-resource settings: What, who, and how to overcome challenges to scale up? Int J Gynaecol Obstet 107 (suppl. 1), S21– S44, S44-5 (2009). 19815204 source

      Not checked in the free run.

    • Rests on an assumption: Research on the effects and benefits of laboring positions has been largely limited because of inability to monitor and collect data in clinical settings with fidelity.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The cold-pressor test is a well-established, safe, and reproducible method to induce a blood pressure response.

    “In this scenario, we demonstrated the responsiveness of our system to controlled changes of BP with a cold-pressor test, a well-established, safe, and reproducible method to induce a BP response (53).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [53] Q. Zhao., Reproducibility of blood pressure response to the cold pressor test: The GenSalt study. Am. J. Epidemiol. 176 (suppl. 7), S91– S98 (2012). 23035148 PMC3530368 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The key drivers of the failure of medical devices in low-income settings are multifactorial and include the cost of maintenance, lack of skilled technicians to maintain the equipment, lack of spare parts, and high consumable costs.

    “The key drivers of this failure are multifactorial and include the cost of maintenance, lack of skilled technicians to maintain the equipment, lack of spare parts, and high consumable costs (50).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [50] B. Compton., “Access to medical devices in low-income countries: Addressing sustainability challenges in medical device donations” (NAM Perspectives, National Academy of Medicine, 2018). source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Continuous data of maternal BP, HR, SpO2, uterine contractility, and FHR are potentially life-saving if acted on, but access is heavily dependent on clinical infrastructure, availability of skilled healthcare providers, and integration of disparate devices and their displays.

    “Continuous data of maternal BP, HR, SpO2, uterine contractility, and FHR are potentially life-saving if acted on, but access is heavily dependent on clinical infrastructure, availability of skilled healthcare providers, and integration of disparate devices and their displays (52).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [52] S. Thaddeus, D. Maine, Too far to walk: Maternal mortality in context. Soc. Sci. Med. 38, 1091– 1110 (1994). 8042057 source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Interpretationreasoning

    These systems can provide a wealth of data in different clinical settings with labeled clinical outcomes, such as that generated by the LABOR study, that offer the opportunity for more population-specific and sensitive delineation of maternal or fetal status to support clinical decision-making.

    “Additionally, these systems can provide a wealth of data in different clinical settings with labeled clinical outcomes, such as that generated by the LABOR study, that offer the opportunity for more population-specific and sensitive delineation of maternal or fetal status to support clinical decision-making.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    By 2025, there will be nearly 700 million smartphones in sub-Saharan Africa, making these mobile devices readily available to be used to operate the sensors for healthcare applications in even the most rural settings.

    “By 2025, it is estimated that there will be nearly 700 million smartphones in sub-Saharan Africa, making these mobile devices readily available to be used in order to operate the sensors for healthcare applications in even the most rural settings (51).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [51] D. Radcliffe, Mobile in Sub-Saharan Africa: Can world’s fastest-growing mobile region keep it up? ZDNet (2018). https://www.zdnet.com/article/mobile-in-sub-saharan-africa-can-worlds-fastest-growing-mobile-region-keep-it-up/. Accessed 23 November 2020.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Other studies have found that the hands-and-knees position has not been associated with negative labor outcomes.

    “Other studies have found that the hands-and-knees position has not been associated with negative labor outcomes (47).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [47] S. Hunter, G. J. Hofmeyr, R. Kulier, Hands and knees posture in late pregnancy or labour for fetal malposition (lateral or posterior). Cochrane Database Syst. Rev., CD001063 (2007). 17943750 PMC8407052

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In previous work, the chest- and finger-mounted sensors were demonstrated to monitor vital signs in both children and adults; the abdominal sensor allows for maternal-fetal monitoring of pregnant women in both high- and low-resource settings as well as the clinical and home settings.

    “In previous work, we demonstrate the ability for the chest- and finger-mounted sensors to monitor vital signs in both children and adults; the abdominal sensor allows for maternal–fetal monitoring of pregnant women in both high- and low-resource settings as well as the clinical and home settings (22, 23).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [22] H. U. Chung., Skin-interfaced biosensors for advanced wireless physiological monitoring in neonatal and pediatric intensive-care units. Nat. Med. 26, 418– 429 (2020). 32161411 PMC7315772 source

      Not checked in the free run.

    • cites [23] H. U. Chung., Binodal, wireless epidermal electronic systems with in-sensor analytics for neonatal intensive care. Science 363, eaau0780 (2019). 30819934 PMC6510306 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    As demonstrated by previous work, neonatal vital signs can also be tracked with the same sensors in both high-resource and low-resource settings as well as support kangaroo care.

    “Additionally, as demonstrated by our previous work, neonatal vital signs can also be tracked with the same sensors in both high-resource and low-resource settings as well as support kangaroo care (22, 48).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [22] H. U. Chung., Skin-interfaced biosensors for advanced wireless physiological monitoring in neonatal and pediatric intensive-care units. Nat. Med. 26, 418– 429 (2020). 32161411 PMC7315772 source

      Not checked in the free run.

    • cites [48] A. S. Ginsburg., Evaluation of non-invasive continuous physiological monitoring devices for neonates in Nairobi, Kenya: A research protocol. BMJ Open 10, e035184 (2020). PMC7200030 32284391 source

      Not checked in the free run.

47 of 47

  • The paper relies on this without support.

    The S1 and S2 peaks in the Doppler ultrasound signal represent closure of the fetal heart valves.

    “The first peak “S1” represents closure of the tricuspid and mitral valves of the fetal heart, and the second peak “S2” represents closure of the pulmonary semilunar valves of the fetal heart (Audio S1).”

  • The paper relies on this without support.

    The electrohysterography contraction can be converted to millimeters of mercury or pressure with a simple calibration.

    “The EHG contraction can be converted to millimeters of mercury (mmHg) or pressure with a simple calibration.”

  • The paper relies on this without support.

    Of all wireless pregnancy monitoring devices currently approved for clinical use, none incorporates maternal vital signs.

    “Perhaps most notable, of all the wireless pregnancy monitoring devices currently approved for clinical use, none incorporates maternal vital signs.”

  • The paper relies on this without support.

    Assessing maternal vital signs such as HR, RR, SpO2, and BP requires additional systems wired to the body and configured to another monitoring system that is often not interoperable.

    “Assessing maternal vital signs such as HR, RR, SpO2, and BP requires additional systems wired to the body and configured to another monitoring system that is often not interoperable.”

  • The paper relies on this without support.

    Research on the effects and benefits of laboring positions has been largely limited because of inability to monitor and collect data in clinical settings with fidelity.

    “Despite these studies, research on the effects and benefits of laboring positions has been largely limited because of inability to monitor and collect data in clinical settings with fidelity.”

  • The paper relies on this without support.

    In both high- and low-resource settings the burden placed on clinical staff in order to obtain physiologic information on a woman and her fetus is significant.

    “In both high- and low-resource settings the burden placed on clinical staff in order to obtain physiologic information on a woman and her fetus is significant.”
6 of 6

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Time-series heat maps assigned to two different figures

    Minor

    The Methods section places the normalized time-series heat maps in Fig. 6, but the figure caption places them in Fig. 5. Fig. 6 is described as showing vital signs by body position.

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 1

  1. World Health Organization, Trends in Maternal Mortality 2000 to 2017: Estimates by WHO, UNICEF, UNFPA (World Bank Group and the United Nations Population Division, 2019).

Cited by

Sorted by citations

Related

Authors
Ryu, D., Kim, D. H., Price, J. T., Lee, J. Y., Chung, H. U., Allen, E., Walter, J. R., Jeong, H., Cao, J., Kulikova, E., Abu-Zayed, H., Lee, R., Martell, K. L., Zhang, M., Kampmeier, B. R., Hill, M., Lee, J., Kim, E., Park, Y., Jang, H., Arafa, H., Liu, C., Chisembele, M., Vwalika, B., Sindano, N., Spelke, M. B., Paller, A. S., Premkumar, A., Grobman, W. A., Stringer, J. S. A., Rogers, J. A., & Xu, S.
Affiliations
  • Sibel (United States) (US)
  • University of North Carolina at Chapel Hill (US)
  • Northwestern University (US)
  • Sibel Inc., Niles, IL 60714;
  • University Teaching Hospital (ZM)
  • University of Zambia (ZM)
  • University of North Carolina Global Projects–Zambia, Lusaka 10101, Zambia;
Corresponding author
  • Stringer, Jeffrey S. A.
  • Rogers, John A.
  • Xu, Shuai
ORCID
Venue
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences
Published
2021-05-10
Volume
118
Issue
20
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
DOI
10.1073/pnas.2100466118
PMC
PMC8157941
OpenAlex
W3161046902
Semantic Scholar
5064baf350d8a9304f964bf07726272852491dcf
Cited by
105
References
56
Citations by year
2026: 16 · 2025: 23 · 2024: 18 · 2023: 29 · 2022: 14 · 2021: 5
FWCI
5.01
Type
journal article
Language
en
Open access
Licence
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • eScholarship (California Digital Library) (submittedVersion, cc-by)
Funders
Bill and Melinda Gates Foundation (OPP1193311)
Topics
  • Physical Sciences › Engineering › Biomedical Engineering › Non-Invasive Vital Sign Monitoring
  • Physical Sciences › Engineering › Biomedical Engineering › Advanced Sensor and Energy Harvesting Materials
  • Physical Sciences › Engineering › Biomedical Engineering › Wireless Body Area Networks
Keywords
pregnancy monitoring, wireless sensors, flexible sensors, vital signs monitoring, antepartum care, postpartum care, fetal monitoring, continuous blood pressure monitoring, resource-limited settings, mobile health, non-invasive monitoring
MeSH terms
Wearable Electronic Devices, Female, Health Resources, Heart Rate, Fetal, Humans, Monitoring, Physiologic, Pregnancy, Uterine Contraction, Vital Signs, Wireless Technology

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-09.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-09.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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