Smart infant monitors: a pediatrician’s guideLatest revision | Image Credit: © AdobeStock

Over the past decade, there has been an emergence of commercially available home devices to help monitor an infant’s vital signs during sleep. These devices aim to provide reassurance and peace of mind to parents with real-time continuous data on an infant’s respiratory rate, heart rate, peripheral oxygen saturation, and even quality of sleep. These technologies can come in the form of cameras, wearable socks, belts, and swaddles. As these devices continue to gain popularity, there is limited guidance for pediatricians and health care providers on how to counsel families regarding their use, how to interpret data generated from these devices, and whether these devices are providing reassurance or preventing adverse outcomes for families with infants.

The technology behind wearable infant cardiorespiratory monitoring devices

Pulse oximeter technology was first developed by Japanese bio-engineer Dr Takuo Aoyagi in 1974 and was driven by the need to have closer monitoring for patients receiving anesthesia.¹ Once limited to operating rooms and hospitals, pulse oximeters have become ubiquitous—now a staple in a household medicine cabinet or on the wrists of those with smartwatches. Pulse oximeters measure pulsatile blood flow using light-emitting diodes (LEDs) and photosensors.²

The 2 main types of pulse oximeters use either transmittance or reflectance to determine the percentage of oxygen saturation in the blood (SpO₂). Transmittance technology, often found in most hospital wrap pulse oximeter probes and commercially available finger pulse oximeters, measures the light that passes through tissues, with the photosensor on the opposite end of the LED. Conversely, reflectance technology, often found in smartwatches that can display SpO₂, measures the amount of light that is reflected from tissue back onto the photosensor, usually on the same side as the LED.²

Most of the commercially available wearable infant pulse oximeter devices utilize transmittance technology, which is thought to be less sensitive to a child’s movements and unwanted signal noise than reflectance probes.^2,3 These devices often require a wrap or sock that can position the LED and photosensor stably on 2 sides of a tissue, most commonly the foot. Some of these devices are outfitted with accelerometers, sensors that measure motion, to help reduce false-positive readings of hypoxia that may come from poor signals secondary to movement.³

Pulse oximeter devices can generate a reading of the SpO₂ (%) and heart rate nearly continuously. Some of the commercially available infant pulse oximeters have also integrated auto-videosomnography technology that uses cameras to determine a child’s chest wall, eyes, and gross body movements to provide added data on respiratory rates, sleep-wake cycles, and even sleep quality.⁴

Devices available in the market

A wide array of products aimed at monitoring cardiorespiratory metrics for infants are on the market, including those commercially available ves those that require a provider prescription and are then considered durable medical equipment. Three common commercially available devices are the Owlet Dream Sock, Masimo Stork, and Nanit Pro Camera.^5-7 Both the Owlet Dream Sock and Masimo Stork devices are cleared by the FDA and targeted for use in infants 0-18 months of age to provide information on infant SpO₂ and heart rate through a smartphone app.^5,7 The Nanit Pro Camera and Owlet Dream Duo camera (which can be bundled with the Dream Sock) can provide information on a child’s respiratory rate, sleep-wake cycles, and environmental factors such as temperature and humidity.^6,7 Manufacturers of these devices claim that they provide continuous cardiorespiratory data to reassure and improve the sleep of caregivers. With the rise of these devices, there has also been a sharp increase in similarly designed infant pulse oximeter socks available for online purchase; however, none of these devices is FDA cleared (Table).

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In understanding the full scope of how these devices have been evaluated and validated, it is important to be aware of the FDA review process for medical devices and the difference between FDA approval and FDA clearance. Most novel prescription drugs, high-risk medical devices, and surgical tools will undergo a rigorous evaluation process involving establishing basic safety profiles, clinical research, regulatory scrutiny, and review of manufacturing practices before getting the FDA’s approval. Conversely, FDA clearance allows for a device or drug company to determine that their device is “substantially equivalent” to already existing technology or medications that have received FDA approval.⁸ As a result, the FDA clearance procedure is often more expedient than the FDA approval process, with less need for novel clinical studies.

Both the Owlet and Masimo companies also have prescription-only “medical-grade” versions of these wireless wearable pulse oximeter devices, such as the Owlet BabySat, that are marketed toward parents and physicians for the monitoring of conditions such as apnea of prematurity, supplemental oxygen dependence, congenital heart disease, and even respiratory syncytial virus bronchiolitis.⁷ These devices are very similar to their commercially available counterparts in terms of monitoring features and the design of the pulse oximetry probe.

Accuracy of the devices

Historically, there have been very limited clinical data to support the accuracy of wearable infant cardiorespiratory monitoring devices. However, as more of these devices have gone through the FDA clearance process, a few studies have emerged, albeit with small sample sizes and limited amounts of monitoring data.

In April 2023, a study performed on 21 preterm and low-birth-weight infants admitted to the neonatal intensive care unit compared the wireless Owlet Smart Sock 3 (an older model of the Dream Sock) to the standard wired Masimo wrap probe pulse oximeter. It monitored the infants for 60 minutes with both devices in place and found a strong correlation in both heart rate and SpO₂ between both devices, although, on the Owlet, SpO₂ became less accurate at lower percent SpO₂ and with motion. The authors concluded that there would need to be significantly more research on this device before it could be implemented in the inpatient setting.⁹

As part of the process of receiving FDA clearance for its medical-grade BabySat, Owlet self-published the results of a home-monitoring clinical study in March 2024. The study enrolled 35 infants aged 2 to 18 months who used the BabySat sock and Masimo Rad-97 medical-grade wired pulse oximeter in the home setting for 2 hours. The BabySat sock performed within 2% of the SpO₂ measured by Masimo’s pulse oximeter and within 3.5 beats per minute (bpm) for heart rate measurement, which is within acceptable industry margins for pulse-oximeter devices.¹⁰

Potential benefits

Wearable cardiorespiratory monitoring certainly promises several benefits for families and clinicians, the most notable of which is caregiver reassurance and peace of mind. The results of a study done by the Owlet company evaluating initial experiences and usage patterns with caregivers using the Owlet Smart Sock found that 75% of caregivers chose to use the device for “peace of mind,” and 94% of parents reported better quality of sleep.¹¹ An added theoretical benefit of the newer wireless smart socks is that they could potentially reduce the risk of strangulation or injury related to corded devices.^7,11

Although these commercially available devices are not marketed as diagnostic and epidemiologic surveillance tools, they have the potential to be used as such. An observational study done in 2021 analyzed the company-provided heart rate data of 100,949 healthy infants using the Owlet Smart Sock in the home setting. It wasdetermined that the incidence of tachyarrhythmia (HR >240 bpm for >60 seconds) was higher than known estimates of incidence in the population that relies on clinical diagnosis alone.¹² While this likely represents subclinical disease, it remains unclear how these results would change clinical management. Analysis of such detailed large cohort data from infants could yield important trends and findings.

Limitations and challenges

Despite the popularity of these devices and the potential benefits both at the individual and population levels, there are several limitations to these devices. Firstly, as described above, there remain limited clinical data regarding the accuracy of these devices, particularly the commercially available (nonmedical-grade) devices. If the accuracy of these devices is impacted by factors such as movement, it can result in false alarms and misrepresent hypoxia or abnormal heart rates in the child. Data from infants who were prescribed a medical-grade pulse oximeter to use in the home suggest that pulse oximeters used in infants had a median of 10 alarms per night.¹³ While the alarm rate is likely to be lower in healthy infants, repeated alarms, especially if they are false-positive alarms, can lead to anxiety, disruption of sleep, or even alarm fatigue.

Secondly, there also remains the significant challenge of how clinicians should interpret and incorporate the results of these devices into their clinical practice. The app interface of most of these devices makes it easy to share results with an infant’s health care provider. However, making clinical recommendations, telehealth management of results, and its effect on overall health care use remains unclear. A 7-year retrospective cohort study in Oklahoma published in 2024 followed infants who used the Owlet Smart Sock for home monitoring of supraventricular tachycardia (SVT) syndrome compared with those who did not receive home monitoring (standard of care for most SVT). The study found that users of the Smart Sock had more emergency department visits and physician telephone calls compared with those who did not. While there was no difference in hospitalization rates, infants who consistently used the device were found to have a shorter length of stay and better-preserved cardiac ejection fraction on echocardiogram.¹⁴

Finally, pulse oximeters, in general, not only home infant cardiorespiratory monitors, also may have some limitations and disparities in accuracy and function based on skin color. An increasing body of literature suggests that in hypoxic states, pulse oximeters may overestimate SpO₂ in populations with darker skin colors and possibly impact clinical management and patient outcomes.¹⁵ While the Owlet website suggests that the devices have equal efficacy among all skin colors,⁷ there remain few published data to support this at a population level.

Practical considerations for pediatricians

As these devices continue to gain considerable popularity among consumers, pediatricians must develop strategies on how to counsel families and integrate the results of these devices into their clinical decision-making and practice workflows. The American Academy of Pediatrics (AAP) does not recommend the use of these infant physiologic monitoring devices specifically as a strategy to reduce the risk of sudden infant death syndrome (SIDS), primarily due to a lack of data to support this use. Furthermore, it expresses concerns that the use of these devices will take the place of other safe sleep practices, such as back-to-sleep and avoiding bed-sharing, which have shown a tremendous reduction in SIDS-related deaths in the past several decades.¹⁶ Results of the initial usage pattern study by Owlet showed that 18% of caregivers who used the Smart Sock were not using safe sleep practices.³ In discussing these devices with caregivers, it will remain imperative to stress that they are not a replacement for well-established safe sleep recommendations.

Another practical consideration when counseling families on these devices is their considerable cost. The Owlet, Masimo, and Nanit devices range from $250 to $400 with additional costs related to optional camera upgrades, accessories, and monthly app subscription fees.^5-7 These high costs may be prohibitive for many families, and formal recommendation for use of these products by the AAP could further widen already existing socioeconomic health care disparities.

It is also important to note that as device companies such as Owlet and Masimo develop their prescription-only, medical-grade, app-enabled wearable sock devices (which also may be partly covered through insurance), pediatricians will have the ability to prescribe these products in lieu of the traditional wired probe devices for medically indicated patients. However, the availability of these devices and commercial popularity should not necessarily change the criteria for medically required at-home cardiorespiratory monitoring.

Conclusion

The emergence of at-home infant cardiorespiratory monitoring devices shows considerable promise for improving caregiver stress and providing reassurance. However, limited clinical data remain on the accuracy, efficacy, and clinical outcomes of these devices. Limitations include costs, alarm fatigue, and the potential for these devices to serve as a replacement for safe sleep practices. As such, it will continue to be challenging for pediatricians and professional associations such as the AAP to recommend or integrate the results of these devices into their clinical decision-making for otherwise healthy infants. However, the move toward FDA approval and development of prescription-only versions of these commercial devices shows promise in the advancement of pulse oximetry technology overall and will hopefully promote more research in this field.

Click here for more from the March Mental Health issue of Contemporary Pediatrics.

References:

1. Miyasaka K, Shelley K, Takahashi S, et al. Tribute to Dr. Takuo Aoyagi, inventor of pulse oximetry. J Anesth. 2021;35(5):671-709. doi:10.1007/s00540-021-02967-z

2. Joo MG, Lim DH, Park KK, Baek J, Choi JM, Baac HW. Reflection-boosted wearable ring-type pulse oximeters for SpO₂ measurement with high sensitivity and low power consumption. Biosensors (Basel). 2023;13(7):711. doi:10.3390/bios13070711

3. Dangerfield MI, Ward K, Davidson L, Adamian M. Initial experience and usage patterns with the Owlet Smart Sock monitor in 47,495 newborns. Glob Pediatr Health. 2017;4:2333794X17742751. doi:10.1177/2333794X17742751

4. Tikotzky L, Ran-Peled D, Ben-Zion H. A preliminary study on the performance of the Nanit auto-videosomnography scoring system against observed video scoring and actigraphy to estimate sleep-wake states in infants. Sleep Health. 2023;9(5):611-617. doi:10.1016/j.sleh.2023.07.014

5. Masimo Stork. Accessed February 5, 2025. https://www.masimostork.com/en-us/product/shop-stork/137719.html

6. Nanit Pro Baby Monitor. Nanit. Accessed October 11, 2024. https://www.nanit.com/products/nanit-pro-camera

7. Owlet Dream Duo 2. Owlet US. Accessed October 11, 2024. https://owletcare.com/products/dream-duo-with-cam-2

8. Center for Devices and Radiological Health. Premarket notification 510(K). FDA. August 22, 2024. Accessed February 5, 2025. https://www.fda.gov/medical-devices/premarket-submissions-selecting-and-preparing-correct-submission/premarket-notification-510k#:~:text=The%20legally%20marketed%20device(s,violation%20of%20the%20FD&C%20Act

9. Thomas M, Day H, Petersen B, et al. Accuracy of wireless pulse oximeter on preterm or <2.5 kg infants. Am J Perinatol. 2024;41(S 01):e1606-e1612. doi:10.1055/s-0043-1768068

10. Owlet Baby Care, Inc. Accuracy evaluation of the FDA-cleared BabySat pulse oximeter in a home-monitoring study. March 2024. Accessed October 11, 2024. https://cdn.shopify.com/s/files/1/1004/3036/files/Accuracy_Evaluation_of_the_FDA_Cleared_BabySat_ManuscriptFormFinal2_4.7.24.pdf?v=1712785298

11. Anjewierden S, Humpherys J, LaPage MJ, Asaki SY, Aziz PF. Detection of tachyarrhythmias in a large cohort of infants using direct-to-consumer heart rate monitoring. J Pediatr. 2021;232:147-153.e1. doi:10.1016/j.jpeds.2020.12.080

12. Ferro DF, Bonafide CP, Fregene N, et al. Parental insights into improving home pulse oximetry monitoring in infants. Pediatr Qual Saf. 2022;7(2):e538. doi:10.1097/pq9.0000000000000538

13. Silverstein L, Dreger N, Anza OA, Behere S. Resource use and clinical outcomes in infants with supraventricular tachycardia monitored with the Owlet Smart Sock. J Pediatr. 2024;268:113946. doi:10.1016/j.jpeds.2024.113946

14. Sharma M, Brown AW, Powell NM, et al. Racial and skin color mediated disparities in pulse oximetry in infants and young children. Paediatr Respir Rev. 2024;50:62-72. doi:10.1016/j.prrv.2023.12.006

15. Moon RY, Carlin RF, Hand I; Task Force on Sudden Infant Death Syndrome and the Committee on Fetus and Newborn. Sleep-related infant deaths: updated 2022 recommendations for reducing infant deaths in the sleep environment. Pediatrics. 2022;150(1):e2022057990. doi:10.1542/peds.2022-057990