Background
The Neonatal Behavioral Assessment NBAS (NBAS) (Brazelton, 1973, Brazelton, 1985, Brazelton and Nugent, 1995, 2011), now in its fourth edition, was developed in 1973 by Dr. T. Berry Brazelton and his colleagues and is still regarded as one of the most comprehensive examinations of newborn behavior available to researchers. The NBAS is best described as a neurobehavioral assessment and is designed to describe the newborn’s behavioral responses to their new extrauterine environment and to document the contribution of the newborn infant to the development of the emerging parent-child relationship. The NBAS has been used to study the effects of wide range of perinatal variables such as prenatal exposure to alcohol, tobacco, cocaine and other drugs, low birth weight, environmental toxins, caesarian section and other pre- and perinatal variables. It is also used in cross-cultural and prediction studies.
The NBAS is based on the assumption that the newborn infant is both competent and complexly organized. The NBAS, therefore, does not merely provide a catalogue of newborn competencies but over the course of serial examinations, allows us to see how the baby’s discrete behaviors are integrated into coherent patterns of behavior and development. The NBAS assesses the newborn’s behavioral repertoire with 28 behavioral items, each scored on a 9-point scale. It also includes an assessment of the infant’s neurological status on 20 items, each scored on a 4-point scale. Seven supplementary items, which are designed to capture the qualitative aspects of the infant’s performance and the more subtle signs of stress, are scored on a 9 point scale. “The Scale gives us the chance to see what the baby’s behavior will tell us,” according to Dr. Brazelton. “It gives us a window into what it will take to nurture the baby.” The NBAS looks at a wide range of behaviors and is suitable for examining newborns and infants up to two months old. By the end of the assessment, the examiner has a behavioral “profile” of the infant, describing the baby’s strengths, adaptive responses and possible vulnerabilities.
Infant individuality
When the NBAS was published in the early 1970s, people were just beginning to appreciate the infant’s full breadth of capabilities, and the only assessments available were designed to detect abnormalities. The NBAS was designed to go beyond available assessments by revealing the infant’s strengths and range of individuality, while still providing a health screen. The NBAS is based on several key assumptions.
First, infants, even ones that seem vulnerable, are highly capable when they are born. “Newborns already have nine months of experience when they are born,” Dr. Brazelton noted. “They are capable of controlling their behavior in order to respond to their new environment.”
Second, babies “communicate” through their behavior, which, although it may not always seem like it, is a rational language. Not only do infants respond to cues around them, like their parents’ faces, but they also take steps to control their environment, such as crying to get a response from their caregivers.
Assessing the baby’s capabilities
In an effort to reveal the full richness of the newborn’s behavioral repertoire, the NBAS was built to include 28 behavioral and 18 reflex items. The exam does not yield a single score but instead assesses the baby’s capabilities across different developmental areas and describes how the baby integrates these areas as they deal with their new environment. When infants are born, they face four developmental tasks vital to their growth. The NBAS examines how well infants manage these interrelated tasks and sees if they may need extra caregiving support in some areas. The most basic challenge facing newborns is to regulate their breathing, their temperature and the rest of their autonomic system, which needs to be functioning properly before infants can concentrate on other developmental areas. High-risk infants may spend most of their energy trying to maintain their autonomic systems, so they cannot focus on other areas of growth. Sights and sounds may overtax them, so looking at their mother’s face may disturb their breathing, or noise may set off tremors, startles or color changes, signals that are assessed by the NBAS. Next, infants strive to control their motor system. Inhibiting random movements and controlling activity levels lets the newborn focus their energy on other developmental tasks vital to growth. If the baby is having difficulty in this area, caregivers can help them by providing as much tactile support as necessary to help them settle down, such as holding or swaddling her. The NBAS assesses the quality of the baby’s tone, activity level and reflexes. Once the baby can manage motor behavior, they will be ready to tackle the next sphere in their developmental agenda: “state” regulation. State is a key developmental concept that describes levels of consciousness, which range from quiet sleep to full cry. Infants’ ability to control their states enables them to process and respond to information from their caregiving environment. The NBAS examiner looks at how infants control their states, and at the transition from one state to another.
For example, the exam reveals how infants respond to light and sound during the sleep state. The examiner briefly shines a light in a sleeping baby’s eyes. Generally, the child blinks and squirms in response. When we repeat the process several times, the infant may tune out the stimulation and remain asleep. The baby’s ability to ignore the stimulation allows them to conserve energy and to develop. Finally, when an infant’s autonomic, motor and state systems are in equilibrium, they are ready to interact socially, the ultimate developmental task. The NBAS shows how babies are ready to be engaged in their new world from the first moments of life. In this portion of the assessment, the examiner looks to see how a baby follows a red ball, a face and a voice.
Best performance
NBAS examiners are trained to get the “best performance” from the child by responding to their behavioral cues and doing everything possible to enable babies to demonstrate the full range of their behavioral capacities. For example, one part of the exam looks at an infant’s ability to self-console when they are upset. Some infants console themselves easily, while others have a more difficult time. If they cannot console themselves, the examiner takes measured steps to help them. Not only do we learn how much support the infant may need at home, but also at what stage they are in terms of completing their developmental agenda.
Research
Research with the NBAS has played an important role in deepening our understanding of the remarkable capacities of the newborn and expanding the very phenomenology of newborn behavior through its uses in a wide range of clinical and cultural settings. Because it is sensitive to even subtle environmental effects, the NBAS has demonstrated that newborn behavior and development can be affected by intrauterine growth restriction; environmental polychlorinated biphenyls (PCBs); prenatal stress-reduction interventions; different modes of delivery; obstetric medication; acute fetal distress; gestational and pregestational diabetes; intrauterine drug exposure; intrauterine exposure to lead; neonatal hyperbiirubinemia; low birth weight; and prematurity and gender, among many variables (e.g., Arya, Chansoria, Konanki, & Tiwari, 2012; Ayesa-Arriola et al. 2023; Campbell et al. 2024; Dreher, Nugent, & Hudgins, 1994; Eyler, Behnke, Conlon, Stewart, Woods, & Wobie, 1997, 1998; Feldman & Eidelman, 2006; Field et al, 2009; Katus et al. 2025; Malak et al. 2021; Ohgi et al., 2002; Paludetto et al, 2002; Rizzo et al., 1990; Sagiv, Nugent, Brazelton, Choi, & Korrick, 2007; Wolf et al., 2002). (See our Publications page for more specific information on NBAS research studies).
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