In 1952, Virginia Apgar MD proposed a scoring system to assess newborns at 5 min after birth, based on five clinical signs: heart rate, respiratory effort, muscle tone, response to stimulation (originally termed “reflex irritability”), and color (1). Following its validation in 1958 (2), the assessment was extended to include 1-minute scoring for earlier evaluation, with the same components repeated at 1, 5, and (when indicated) 10 min.

The Apgar score comprises five components, each scored 0–2 (1): color (reflecting peripheral perfusion), heart rate, reflex irritability, muscle tone, and respiratory effort. This scoring effectively quantifies signs of neonatal depression, including cyanosis/pallor (score 0–2), bradycardia (<100 bpm = score 1, absent = 0), depressed reflexes (score 0–2), hypotonia (score 0–2), and apnea/gasping (score 0–2). Current guidelines mandate scoring at 1 and 5 min for all newborns, with continued 5 min interval assessments until 20 min for scores below 7 (3, 4). The score serves three primary functions: immediate neonatal assessment, documentation of clinical status, and (when persistently low) identification of infants who may benefit from closer monitoring. Although population-level studies have shown statistical associations between Apgar scores and long-term outcomes, the score was never intended to predict individual neurodevelopmental trajectories. Current neonatal resuscitation guidelines emphasize that only heart rate and respiratory effort (not the overall Apgar score) should guide immediate interventions. Despite its widespread adoption as the standard method for reporting neonatal status immediately after birth (5, 6), the Apgar score has notable limitations: it cannot, by itself, diagnose perinatal asphyxia or accurately predict individual neurodevelopmental outcomes (7).

Although it remains the most widely used neonatal assessment tool (8), numerous studies have identified three key limitations: inter-rater variability in subjective components (particularly color and tone assessment), confounding influences of gestational age and maternal medications, and the lack of a linear relationship with acid-base status (7, 9).

Recent systematic reviews (7, 9) have highlighted persistent gaps in the psychometric validation of the Apgar score, including the absence of an established minimal clinically important difference, inadequate statistical power for rare outcomes (such as cerebral palsy), and context-dependent predictive value. These limitations may introduce measurement bias that affects both clinical decisions and research outcomes (10, 11).

Infrared thermography, based on the measurement of infrared radiation (12), has been recently evolved for medical temperature monitoring (13–16) and diverse clinical applications, including the evaluation of inflammation and vascularization (17, 18). Abnormalities such as malignancies, inflammation, and infection cause localized increases in temperature which have been shown as hot spots (13) or as asymmetrical patterns (15) in an infrared thermogram.

The widespread adoption of this technology stems from its precision, reliability, and ease of use, offering rapid, non-contact, non-invasive, and non-radiating diagnostic capabilities for both therapeutic and preventive medical applications (19–23).

As the clinical signs captured by the Apgar score are closely related to perfusion (perfusion is the principal vector of heat distribution in the human body), we proposed to describe thermal patterns in neonates during the first minutes after birth and to benchmark these descriptive patterns against concurrently assigned Apgar scores. Specifically, we hypothesized that newborns with lower Apgar scores at 1 min would display observable differences in early surface thermal adaptation compared with higher-scoring peers.

We focused on skin surface temperature distribution rather than central temperature, as peripheral perfusion reflects the cardiovascular and respiratory components captured by the Apgar score. This proof-of-concept study aims to establish whether thermal biomarkers merit further validation against clinical outcomes.

Of 223 enrolled neonates, 3 were excluded due to all images being unusable (severe occlusion or blur), leaving 220 participants in the analysis. Among these, 177 (80.5%) had Apgar scores of 10 at all time points (1, 3, 5, and 10 min), and 43 (19.5%) had Apgar scores <10 at one or more time points. Based on 1 min Apgar scores, 11 infants were classified in the low Apgar group (≤7) and 209 in the high Apgar group (≥8). The number of infants per group remained constant across all time points.

Maternal and neonatal baseline characteristics are presented in Table 1. Maternal age ranged from <25 to ≥35 years (51.4% aged 25–34 years), 64.3% were born in Europe, and 58.4% had BMI ≥ 25. Gestational age was 38.5 (0.9) weeks, and birth weight was 3,315 (464) grams. Maternal and neonatal baseline characteristics are presented in Table 1. Most characteristics did not differ significantly between the low- and high-Apgar groups, including BMI, parity, gestational diabetes, fetal growth restriction, analgesia type, cesarean type, gestational age, sex, and birth weight (all p > 0.05). However, a significant difference in maternal age distribution was observed (p = 0.001), with a higher proportion of mothers aged <25 years in the low-Apgar group (27.3% vs. 1.9%). This finding should be interpreted with caution given the small absolute numbers (3 vs. 4 mothers).

Clinical interventions included mask ventilation (n = 14), CPAP support (n = 38), and no infants required intubation or chest compression. Overall, 52 neonates (23.6%) required some form of resuscitation or respiratory support.

All Apgar scores were assessed by two experienced midwives independently under standardized conditions (heated resuscitation table with optimal lighting). Assessments were performed at 1, 3, 5, and 10 min post-birth.

“Birth is the riskiest moment of your life. It's fundamental to quickly assess a newborn's status and immediately identify those who need urgent care.” (V. Apgar 1953). Birth is still a high-risk event in 2025: a newborn is 500 times more likely to die at birth than during the rest of their life. Assessing the newborn's clinical condition is a fundamental step, as it determines both the immediate management and the long-term prognosis.

The Apgar score, introduced by Virginia Apgar, has played a pivotal role in standardizing this early evaluation. Its simplicity and reproducibility have made it the global reference for assessing neonatal vitality. However, inter-observer variability and the subjectivity of some components, particularly color and tone, remain important limitations. The present study explored whether infrared thermography, a non-contact and objective technique, could provide complementary information about early adaptation by visualizing peripheral perfusion patterns immediately after birth.

Humans are homeothermic beings, and thermoregulation is a key physiological process, particularly during the neonatal transition. Heat is generated through non-shivering thermogenesis in brown adipose tissue and transported by blood flow, making temperature distribution an indirect marker of circulatory adaptation (25–28) and a key aspect of neonatal physiology (24). In this context, surface thermography offers a way to monitor peripheral heat diffusion, which is closely linked to perfusion and vascular regulation in the minutes following delivery.

In this feasibility study, infrared imaging revealed observable differences in surface temperature distribution between newborns with low and high Apgar scores during the first minutes of life. While rectal (central) temperature measurements suggested a tendency toward higher initial values in low-Apgar infants, likely related to delayed cooling, surface thermal profiles demonstrated a progressive warming pattern and eventual convergence between groups. These findings are descriptive and should be interpreted qualitatively, but they suggest that infrared thermography may capture subtle differences in thermal adaptation that parallel circulatory stabilization.

The visual representation developed for this study (Figure 4) was designed as a straightforward graphical tool for summarizing thermal data. By simultaneously displaying the spatial and quantitative distribution of temperature ranges, this visualization provides a rapid, intuitive overview of each newborn's thermal adaptation pattern. Such representations could, in future work, support automated or semi-automated analyses for early assessment of peripheral perfusion.

The immediate potential of thermal imaging lies in its ability to serve as a non-contact, objective adjunct to conventional clinical assessment. In practice, a thermal camera could be mounted above the resuscitation table to provide real-time, automated visual feedback on perfusion and thermal adaptation without disturbing care. Future work should focus on developing and validating machine-learning algorithms capable of recognizing characteristic thermal patterns over time. Such approaches could eventually generate a continuous “thermal adaptation score” to complement, rather than replace, the Apgar score. Larger prospective studies will be required to evaluate whether these thermal biomarkers correlate with short-term morbidities such as prolonged respiratory support or early signs of hypoxic-ischemic injury.

The broader variability observed among high-Apgar newborns likely reflects normal physiological diversity in thermal adaptation rather than a technical artifact. In contrast, the relative homogeneity in the low-Apgar group may arise from both smaller sample size and reduced thermal reactivity during early circulatory compromise. Importantly, these descriptive differences do not imply that infrared thermography can increase the reliability of the Apgar score. Rather, thermography provides an objective, quantitative view of one physiological component—peripheral perfusion—without assessing respiratory effort, heart rate, or reflex response. The purpose of thermal imaging at this stage is not to predict the Apgar score, but to explore whether this technology can eventually serve as a non-contact adjunct to standard assessment by quantifying aspects of neonatal adaptation that are otherwise evaluated qualitatively.

This study has several limitations. In addition to technical constraints, methodological factors may have influenced our observations. Maternal temperature was not systematically documented, and subtle variations could have affected early neonatal thermal readings despite exclusion of febrile mothers. All thermographic measurements were performed under a standardized radiant warmer, which may have impacted absolute skin temperature values but was identical across participants. Missing data were more frequent in the low-Apgar group due to clinical priorities during resuscitation, limiting early comparisons. Finally, restricting inclusion to term cesarean deliveries enhanced environmental control but reduced generalizability to vaginal or preterm births. Future studies should include more diverse delivery contexts and systematically record maternal and environmental parameters to strengthen interpretability.

Furthermore, although our cohort included infants with diverse skin tones, this factor is unlikely to have influenced thermal measurements. In long-wave infrared thermography, human skin emissivity is uniformly high across all pigmentation levels (ε ≈ 0.97–0.98), resulting in minimal bias related to skin color (13, 15). Additionally, the significant difference in maternal age distribution between groups, with younger mothers overrepresented in the low-Apgar group, represents a potential confounding factor. However, the small sample size of the low-Apgar group (n = 11) precludes adjustment for this variable or definitive conclusions about its influence on the observed thermal patterns.

In summary, this proof-of-concept study supports the feasibility of infrared thermography for observing neonatal thermal adaptation immediately after birth. While additional validation in larger and more heterogeneous cohorts is necessary, these findings provide a foundation for developing automated, quantitative tools that could enhance the objectivity and precision of early neonatal assessment.

This proof-of-concept study demonstrates the feasibility of infrared thermography for visualizing thermal adaptation patterns in the first minutes of life. The descriptive differences observed between infants with low and high Apgar scores suggest that thermography could serve as a non-contact, objective adjunct to conventional assessment. Future work will refine image-processing methods and develop automated algorithms to analyze thermal dynamics in real time. Validation in larger, more heterogeneous cohorts will be essential to determine clinical relevance and generalizability. This study provides a foundational framework for using thermal imaging as a complementary, non-invasive tool to monitor the physiological transition at birth.