Does My Baby's Skin Colour Change What the Oxygen Monitor Shows?

What recent research from Arkansas, Atlanta and California tells families about the little red light on their newborn's foot, and why researchers now measure skin itself rather than relying on race

Almost every baby in a neonatal intensive care unit wears a small sensor with a glowing red light that measures how much oxygen is in the blood. After studies in adults suggested these monitors can overestimate oxygen levels in people with darker skin, researchers asked whether the same problem affects newborns. New studies suggest that newborn skin is different, that a baby's race is a poor guide to their actual skin tone, and that so far there is no clear sign of a meaningful skin-tone difference in newborn monitor accuracy.

The monitor every family comes to know

If your baby has spent time in a neonatal intensive care unit (NICU), you have probably watched the numbers on the screen above the cot more closely than almost anything else. One of the most important is the oxygen saturation, often shown as "SpO2" or "sats". It comes from a small sensor, called a pulse oximeter, usually wrapped around a baby's foot or hand. The sensor shines red and infrared light through the skin and measures how much comes out the other side. Because blood carrying plenty of oxygen absorbs light differently from blood carrying less, the monitor can estimate oxygen levels without a needle. The care team uses that number many times a day to decide how much extra oxygen or breathing support your baby needs.

How a worry about fairness began

For decades, doctors assumed these monitors worked equally well for everyone. In 2020, researchers in the United States compared oximeter readings in adults with the more accurate measurement from a blood sample. They found that dangerously low oxygen levels were missed more often in Black patients than in White patients [1]. Other large adult studies found similar gaps, and some linked them to worse health outcomes [2], [3]. Scientists had noticed hints of this even earlier in laboratory testing [4]. One idea is that melanin, the natural pigment that gives skin its colour, absorbs some of the light the sensor depends on, although this has not been proven [5].

That news understandably worried parents and NICU teams. Babies born early can be harmed both by too little oxygen and by too much. Studies of very premature babies have linked repeated drops in oxygen to later lung disease and to problems with development [6], [7]. If the monitor were quietly less accurate for some babies, those babies could spend more time with low oxygen without anyone knowing. But the few newborn studies that existed gave mixed answers [8], [9], and nearly all of them grouped babies by the race of the mother rather than by how dark or light the baby's skin actually was.

Newborn skin is not simply small adult skin

A team of neonatologists and dermatologists at the University of Arkansas for Medical Sciences, who had already written about this problem in infants and young children [10], set out in 2025 to fix that blind spot. Their first paper was a careful review of everything known about measuring skin colour in newborns [5]. They found only eight studies that had measured newborn skin pigment with an instrument rather than by eye, and almost none had included babies with darker skin.

The review explains some surprising facts about newborn skin. Babies are born with all the pigment-making cells they will need, but those cells make much less melanin at birth than they will later. The outer layers of a newborn's skin are about 30% thinner than an adult's. And simple colour charts are unreliable: the most famous one, the Fitzpatrick scale, was designed to predict how adults tan or burn in the sun [11], and even a chart made especially for newborns matched instrument measurements only moderately well [12]. A better option is a small handheld device, a little like a camera held against the skin, that measures reflected light and turns it into numbers describing skin tone [13], [14]. The review's advice to other researchers was to measure the skin right where the oxygen sensor sits.

Measuring 100 babies' feet

In their second paper, the same team did exactly that [15]. Between August 2023 and February 2025, they studied 100 babies in the NICU and heart intensive care unit at Arkansas Children's, a regional referral hospital. With parents' permission, a trained researcher gently placed the handheld device on the top of each baby's foot, where the oxygen sensor usually goes, three times in a row. As is standard in newborn research, each baby's race was recorded from the mother's own description. Thirty-three babies were Black, 57 were White, 7 were Hispanic and 3 were of another background.

What they found: the groups overlapped a lot

On average, Black babies did have darker skin at the foot than White babies. But the averages hid a great deal of overlap. Roughly two-thirds to three-quarters of the range of skin tones was shared between the two groups. Put simply, knowing a baby's race told you surprisingly little about how dark that particular baby's skin was. Of the ten babies whose skin fell into the darkest measured category, six were recorded as White. This was not explained by babies having parents of different races, because almost all had parents of the same race.

An everyday comparison may help. Men are taller than women on average, yet you would never guess a particular person's height just from knowing whether they are a man or a woman, because so many women are taller than many men. Skin tone in these newborns behaved in much the same way. The authors point out that race is a social category, and that it is genes and environment, not the label itself, that shape how much pigment a baby's skin contains [15]. That matters for monitors because a light sensor responds only to the skin in front of it, never to the box ticked on a form.

Another finding was just as striking. How early a baby was born mattered more than race. Babies born earlier and smaller had skin that read as darker on the device, whatever their race. The researchers think this is because very premature babies have thin, almost see-through skin with visible tiny blood vessels, not because they have more pigment [15].

Do the monitors actually read differently?

The Arkansas papers measured skin, not monitor accuracy. Two newer studies, published in 2026 and available to us only in summary form, tested the monitors themselves. A team at Children's Healthcare of Atlanta looked back at records from 1,645 newborns and compared monitor readings with blood tests taken up to 10 minutes apart [16]. The monitors tended to read higher than the blood test, but equally so for Black, White and Hispanic babies. A second study, called the Neonatal Pulse Oximetry Accuracy and Disparities by Skin Pigmentation study (NeoPODS), was led from the University of California, Davis, in two NICUs [17]. Its team measured each baby's skin tone with instruments and compared monitor readings with blood samples taken at almost exactly the same moment in 70 newborns. On average the monitor was off by only about 1%, slightly on the low side, with no meaningful difference by skin tone. Only one baby had a reading that the researchers counted as hidden low oxygen, and that baby had light skin.

Why did the two studies look so different? The summaries alone cannot fully answer that. The Atlanta team was looking back over 12 years of hospital records, where the monitor number and the blood test were usually taken within a minute or so of each other but could be up to 10 minutes apart, and the published summary does not say which foot or hand the sensor was on. The California-led team set up their study in advance so that the sensor sat on the same limb the blood came from and the reading was taken in the 30 seconds before the sample. Careful planning of this kind is better at showing how accurate the device itself is.

What this means for your baby

For families, the message is reassuring but not the final word. The newest newborn evidence does not show that the oxygen monitor works worse for babies with darker skin, and the Arkansas work shows why it would be a mistake to "adjust" the numbers based on a baby's race: race and actual skin tone simply do not line up closely enough in newborns [15]. Every monitor has some error for every baby, which is why your baby's team also looks at breathing, colour, behaviour and, when needed, blood tests. The same kind of sensor is used for the heart screening test offered to newborns before they go home, which you can read about in our newborn heart screening article.

It is always reasonable to ask questions. You might ask where the sensor is placed, what oxygen range the team is aiming for, and what they would do if the monitor and your baby's condition did not seem to match. Good NICU teams welcome these questions.

What researchers are working on next

These studies were small, and most came from one or two hospitals. Researchers now want larger studies in many hospitals that measure every baby's skin tone with instruments, follow premature babies as their skin matures over weeks, include enough babies across the whole range of skin tones, and test different monitor brands at the low oxygen levels that matter most [5], [14]. The shift these papers represent is simple but important: to learn whether a light-based device treats every baby fairly, scientists have to measure the skin the light passes through, not the label on the chart.

References

  1. Sjoding MW, Dickson RP, Iwashyna TJ, Gay SE, Valley TS. Racial Bias in Pulse Oximetry Measurement. N Engl J Med. 2020;383(25):2477-2478. doi:10.1056/NEJMc2029240 ↩
  2. Wong AI, Charpignon M, Kim H, et al. Analysis of Discrepancies Between Pulse Oximetry and Arterial Oxygen Saturation Measurements by Race and Ethnicity and Association With Organ Dysfunction and Mortality. JAMA Netw Open. 2021;4(11):e2131674. doi:10.1001/jamanetworkopen.2021.31674 ↩
  3. Valbuena VSM, Seelye S, Sjoding MW, et al. Racial bias and reproducibility in pulse oximetry among medical and surgical inpatients in general care in the Veterans Health Administration 2013-19: multicenter, retrospective cohort study. BMJ. 2022;378:e069775. doi:10.1136/bmj-2021-069775 ↩
  4. Feiner JR, Severinghaus JW, Bickler PE. Dark Skin Decreases the Accuracy of Pulse Oximeters at Low Oxygen Saturation: The Effects of Oximeter Probe Type and Gender. Anesth Analg. 2007;105(6 Suppl):S18-S23. doi:10.1213/01.ane.0000285988.35174.d9 ↩
  5. Sharma M, Pickhardt AJ, McClanahan M, Tong L, Evans MS. Objective Assessment and Quantification of Skin Color and Melanin in Neonates and Infants: A State-of-the-Art Review. Pediatr Dermatol. 2025;42(3):447-456. doi:10.1111/pde.15902 ↩
  6. Poets CF, Roberts RS, Schmidt B, et al. Association Between Intermittent Hypoxemia or Bradycardia and Late Death or Disability in Extremely Preterm Infants. JAMA. 2015;314(6):595-603. doi:10.1001/jama.2015.8841 ↩
  7. Jensen EA, Whyte RK, Schmidt B, Bassler D, Vain NE, Roberts RS. Association between Intermittent Hypoxemia and Severe Bronchopulmonary Dysplasia in Preterm Infants. Am J Respir Crit Care Med. 2021;204(10):1192-1199. doi:10.1164/rccm.202105-1150OC ↩
  8. Vesoulis Z, Tims A, Lodhi H, Lalos N, Whitehead H. Racial discrepancy in pulse oximeter accuracy in preterm infants. J Perinatol. 2022;42(1):79-85. doi:10.1038/s41372-021-01230-3 ↩
  9. Foglia EE, Whyte RK, Chaudhary A, et al. The Effect of Skin Pigmentation on the Accuracy of Pulse Oximetry in Infants with Hypoxemia. J Pediatr. 2017;182:375-377.e2. doi:10.1016/j.jpeds.2016.11.043 ↩
  10. 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 ↩
  11. Fitzpatrick TB. The Validity and Practicality of Sun-Reactive Skin Types I Through VI. Arch Dermatol. 1988;124(6):869-871. doi:10.1001/archderm.1988.01670060015008 ↩
  12. Maya-Enero S, Candel-Pau J, Garcia-Garcia J, Giménez-Arnau AM, López-Vílchez M. Validation of a neonatal skin color scale. Eur J Pediatr. 2020;179(9):1403-1411. doi:10.1007/s00431-020-03623-6 ↩
  13. Ly BCK, Dyer EB, Feig JL, Chien AL, Del Bino S. Research Techniques Made Simple: Cutaneous Colorimetry: A Reliable Technique for Objective Skin Color Measurement. J Invest Dermatol. 2020;140(1):3-12.e1. doi:10.1016/j.jid.2019.11.003 ↩
  14. Vasudevan S, Vogt WC, Weininger S, Pfefer TJ. Melanometry for objective evaluation of skin pigmentation in pulse oximetry studies. Commun Med (Lond). 2024;4(1):138. doi:10.1038/s43856-024-00550-7 ↩
  15. Sharma M, Brown AW, Chung S, Sexton KW, Schootman M, Mourani PM. Race Is an Incomplete Surrogate for Skin Pigmentation in Neonates with Potential Relevance for Pulse Oximetry. J Pediatr. 2025;286:114720. doi:10.1016/j.jpeds.2025.114720 ↩
  16. Lin M, Mills M, Jergel A, Aljiffry A, Oster ME. Pulse oximetry and arterial saturation bias in neonates: retrospective analysis by race & ethnicity. Cardiol Young. 2026;36(2):325-331. doi:10.1017/S1047951125110718 ↩
  17. Siefkes H, Holla I, Giusto E, et al. Neonatal Pulse Oximetry Accuracy and Disparities by Skin Pigmentation (NeoPODS): A Prospective Study. J Pediatr. 2026:115114. doi:10.1016/j.jpeds.2026.115114 ↩