Stress assessment instruments for hospitalized preterm newborns: scoping review

Approximately 13,4 million preterm newborns are born annually worldwide, a number that has progressively decreased over the years, but preterm birth complications continue to be the leading cause of death among children under 5 years of age [1]. In 2020, there was an estimated 3,4 million preterm birth, worldwide [1]. In Portugal, in 2023, the rate of premature live births, corresponding to births before 37 completed weeks of gestation and regardless of birth weight [2, 3], was 7,2%, corresponding to a total of 6190 births [4].

Prematurity assumes special relevance in the evaluation of perinatal health indicators and is associated with an increased risk of compromised neurodevelopment [5‐7], a rate that in very premature infants, whose gestational age is less than 28 weeks, is between 15 and 25% [8, 9]. Preterm birth influences the healthy evolution of the child [10], increasing the probability of problems occurring in different areas and moments of child development [5‐7, 11] and whose growth is contrary to what was expected and intended [12].

The main cause of neonatal mortality is still prematurity, but the survival of preterm newborns has been increasing, including that of very premature newborns [8, 9]. Despite the technological advances leading to improved survival of preterm newborns, namely newborns with very low birth weight [3, 13], the preterm newborn term is associated with a higher risk of mortality and morbidity [13, 14]. This fact is due to the increased tendency of excessive weight loss, food intolerance, hyperbilirubinemia, hypoglycaemia, hypothermia, respiratory stress, apnea and weak sucking, compared to the term newborn [14].

The highly technological environment existing in intensive care units, essential for survival, contributes with a potentially devastating and traumatic effect on newborns and their future lives, due to early and frequent exposure to multiple stressors, namely, hyperstimulating sensory stimuli, constant invasive procedures, lack of satisfaction of basic needs, especially the constant interruption of sleep and also by maternal and family deprivation that deprive them of affective relationships, protection and security [5, 15, 16].

By understanding that the hospitalization of preterm newborns is a traumatic event, professionals have a duty to increase their knowledge in order to incorporate the best practices based on evidence, minimizing and mitigating the associated toxic stress, contributing favourably to the reduction of long-term complications associated with language disorders, learning difficulties or emotional, mental and/or behavioural disorders [5‐7, 15, 17‐19].

The stress experienced in the perinatal period constitutes a pathogenic component that needs to be studied and deepened, to improve practices, since, due to their developmental phase, preterm newborns are not provided with effective strategies to deal with the various stimuli and, subsequently, reach a state of harmony and well-being.

Nurses must provide, in their care, a properly organized environment that promotes the harmonious development of the newborn, to minimize harmful stimuli and individualize stimulation based on the behavioural and physiological responses of the newborn, avoiding practices that are simply routine but unnecessary [6, 20‐22]. Some author also suggest that nurses must create algorithms and practice standards to ensure the implementation of evidence-based practice [22] to manage stress exposure.

The newborn subject to constant sensory overload, has difficulties in managing energy in order to achieve regulation in all its subsystems [23], showing signs of exhaustion and stress. Faced with the nursing diagnosis, “stress” or “risk of stress” [24], which is always present in hospitalizations in neonatology, a careful assessment of the autonomic, motor, attention-interaction, self-regulation and general state of the subsystems is necessary [25, 26]. The preterm newborn must be observed in a systematic and structured way, before, during and after any intervention, aiming at the correct evaluation and interpretation of his behaviour. Therefore, it is important that the nurses perceive the neurobehavioral functioning of the preterm newborn, identifying the signs and symptoms of stress, aiming at the timely planning of interventions that minimize and prevent stress. The assessment is the first step of nursing process and nurses use several different instruments to provide safe and evidence-based care to patients. Systematic and structured assessment tools ensure the rigour of collected data and help nurses to evaluate the newborn stress correctly.

The aim of this scoping review (ScR) is to identify and map the instruments for assessing the stress of preterm newborns (NB) hospitalized in neonatology units in the scientific evidence. For this purpose, the following research intends to answer the question:

In pursuit of the determined objective and question, a scoping review was developed on the instruments for assessing the stress of preterm newborns hospitalized in neonatology units, using the methodology presented by JBI (2020) and the PRISMA model ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extended for Scoping Reviews) for structuring the collected information [27].

At the beginning of this path, 209 articles were identified for analysis in this review. Duplicate articles in the various databases were removed, leaving 109. An article obtained after analysing the references of the studies included in this review was also included. At the end of the process, 19 studies were obtained for full reading. 10 articles met the defined criteria, so they were included in this study. Of the total of excluded articles, 6 did not present the intended intervention (stress assessment), 1 was duplicated, 1 had no indication for stress and the last one was intended for another population, differently from the one defined in the inclusion criteria.

The 9 articles correspond to primary studies. The most frequent study design was experimental (n = 4), followed by clinical trial (n = 2), cross-sectional (n = 1), observational (n = 1) and methodological (1). Table 2 summarizes the main information extracted from the studies, namely the stress assessment tools used.

After analysing the studies, seven instruments were found in these studies, Neonatal Infant Stressor Scale (NISS) (n = 6), Newborn Stress Scale (NSS) (n = 3), ALPS – Neo pain and stress assessment scale (n = 1), Neurobehavioral Assessment of Preterm Infant (NAPI) (n = 1), NICU Network Neurobehavioral Scale (n = 1), Neurobiologic Risk Score (n = 1) and Newborn Comfort Behavior Scale (n = 1).

Aiming a greater understanding of the identified instruments, Table 3 shows their characterization, namely their aims and indicators.

After analysis, 3 of the scales refer to the assessment or prediction of the risk of alterations in the neurodevelopment of newborns (Neurobiologic Risk Score [36], NICU Network Neurobehavioral Scale [31] and NAPI [30]).

The Newborn Comfort Behavior Scale [17] and the ALPS—Neo pain and stress assessment scale [31] are instruments that aim to assess pain and stress.

The most mentioned scale in the included studies was the NISS [20, 30, 31, 33, 35, 37]. This scale aims to identify stress-generating experiences (stressors) in the daily routine of care for hospitalized newborns.

The NSS [17, 32, 34] is a scale that aims to assess the stress of newborns hospitalized in neonatology and includes 8 behavioural items, promoting a non-invasive assessment.

The assessment of newborn’ stress admitted to NICU is a crucial data of neuroprotective and humanized care, particularly because of the impact that environmental stimuli, invasive procedures, and clinical conditions can have on their well-being and development. However, during the research for instruments specifically designed to evaluate neonatal stress, it was observed that most available scales focus predominantly on pain assessment, with few tools dedicated exclusively to stress.

The Newborn Comfort Behavior Scale [17] and the ALPS—Neo pain and stress assessment scale [31] are good examples of that reality, because they are instruments that aim to assess pain and stress together, however they were accepted in this review because they were aimed at assessing also stress. Pain assessment was an exclusion element in the instruments that were intended to be found. This predominance of pain-focused scales partly reflects the heightened awareness of the adverse effects of untreated pain in newborns. Nevertheless, it is essential to recognize that stress and pain are distinct experiences, although they are often interrelated. Painful experiences are always stressful, but there are experiences that aren't recognized as painful, but they are very stressful, like mother separation or hyperstimulant environment in NICU. Both involve similar physiological and behavioral responses, but the use of pain-assessment scales may underestimate or fail to capture the full extent of stress experienced by newborns.

Identifying and monitoring neonatal stress is equally important, as it can have long-term repercussions, including an increased risk of emotional, behavioral, and cognitive developmental issues [5‐7, 15, 16]. Neuroprotective care aims to provide care based on the newborn’s behavioral response, individualizing care to their rhythm and focusing on their need [5‐7].

Neurobiologic Risk Score [36], NICU Network Neurobehavioral Scale [31] and NAPI [30]), aim to assess the progression of early neurobehavioral and to predict neurodevelopmental problems, so they do not correspond to what was intended with this review.

The NISS was introduced as a practical and non-invasive method for assessing the cumulative stress experienced by preterm infants in the NICU [20, 30, 31, 33, 35, 37]. With this instrument researchers can concluded that neonatal stress varies significantly between infants and over time, with the highest average scores occurring in the first week after birth. NISS scores are closely linked to various clinical factors, potentially indicating the severity of illness during the NICU stay [37]. The researchers also studied the role of stress in the NICU, and they concluded that NISS can be used as a reasonable indicator of a newborn's acute stress [33]. However, the limitation of this instrument is the fact that it evaluates the number of interventions, and not the newborn's response to them. NISS provides a practical way to estimate cumulative stress in preterm infants, but it does not assist nurses in recognizing specific signs of stress in these newborns, so important to individualize the nursing care according to newborn’s tolerance.

NSS promotes a non-invasive stress assessment, using only observation [17, 34]. It was developed by Ceylan & Bolʟşʟk in 2017 in Turkey and is only available in this language. As it is a behavioural scale, it cannot be applied to newborns under analgesic, sedative, or muscle relaxant medication, or with neurological disease, congenital anomalies, hyperbilirubinemia, or undergoing surgery [17]. It is an easy-to-use instrument and does not involve associated costs, as it does not require specific equipment. According to the authors, this instrument will contribute to the planning of individualized care based on the stress of newborns hospitalized in NICU and can also be used in studies that aim to assess neonatal stress [17].

Furthermore, distinguishing between pain and stress is essential for implementing targeted and effective interventions, preventing future development problems.

It is crucial for nurses to differentiate between pain and stress in preterm infants admitted to the NICU. While both can have negatively impact on the infant’s development and well-being, they require different management approaches. Acute pain is typically a response to a specific stimulus and often necessitates immediate intervention, such as analgesics or non-pharmacological strategies. Stress, on the other hand, may result from cumulative stressors like noise, handling, mother separation or even pain, and it’s managed through strategies to minimize the negative impact of that stressors or to extinguish the stressors. Recognizing and addressing these distinct concepts, although the responses of newborn could be similar, ensures that preterm infants receive appropriate and individualized care to support their recovery and development. Researchers found that infants' total stress scores during and after tube feeding were higher in the semi-elevated supine position compared to the semi-elevated right lateral position, and this difference was larger [34]. These findings were possible because a stress assessment scale was used, allowing for the precise detection of differences in stress levels between the two feeding positions.

NICU must adapt their routines, care practices and environment to minimize preterm newborn stress. This includes implementing strategies to reduce noise and light exposure, minimizing unnecessary handling, and ensuring a supportive environment. Adjusting daily care routines to prioritize the infant's comfort and incorporating family-centered practices, such as kangaroo care, can significantly reduce stress levels. These adaptations are essential to minimize stress and consequently to promote the infant's neurological development, physiological stability, and overall well-being during their stay in the NICU. There is, therefore, a clear need to expand the range of available tools to include validated and specific instruments for neonatal stress, fostering a more holistic approach to the care of hospitalized newborns. This would enable more precise interventions and contribute to neonatal practices that fully respect the emotional and physical needs of this vulnerable population.

The findings of this review highlight the critical importance of identifying and assessing neonatal stress in the NICU setting as part of neuroprotective and humanized care. While significant progress has been made in understanding the impact of environmental and procedural stressors on newborns, the limited availability of specific tools to assess neonatal stress remains a key challenge.

Most existing instruments, such as the Newborn Comfort Behavior Scale and the ALPS-Neo, focus predominantly on pain and stress combined, reflecting a historical emphasis on pain management. However, stress and pain, though interconnected, are distinct phenomena that require differentiated approaches to assessment and management. The lack of tools specifically designed to evaluate stress independently from pain underscores the need for further research and development in this area.

The review also underscored the potential of tools like the NISS and NSS for stress assessment. While the NISS provides valuable insights into cumulative stress through a non-invasive approach, its limitation lies in its inability to capture individual newborn responses. On the other hand, the NSS offers a behavioral-based assessment that aligns with neuroprotective care principles, though its applicability is constrained by factors such as language availability and exclusion of certain populations.

Given the implications of neonatal stress on long-term development, there is a pressing need for NICUs to adapt their practices to minimize stressors. This includes creating a supportive environment, prioritizing individualized care, and integrating family-centered practices. Moreover, fostering the development and validation of new tools focused exclusively on stress assessment would enable nurses to implement more precise interventions tailored to the unique needs of each newborn.