Journal of Pediatric Psychology, Vol. 25, No. 8, 2000, pp. 577–582
Brief Report: The Brazelton Neonatal Behavioral Assessment Scale Detects Differences Among Newborn Infants of Optimal Health ¨ ran Sabel,2 MD, PhD Cristina Lundqvist,1 MS, and Karl-Go 1
Lund University and 2Bora˚s Hospital
Objective: To determine whether the Brazelton Neonatal Behavioral Assessment Scale (NBAS) can detect behavioral differences in newborn infants of optimal health and, if such differences appear, also detect gender differences among those neonates. Methods: Participants were a group of healthy Swedish neonates, 20 boys and 18 girls. The infants were assessed by the NBAS under standardized conditions at 48–72 hours of age, at the midpoint between two meals. Results: All items except those in the dimensions Autonomic System and Motor System had a wide interquartile range. The trend was that girls had higher median item profiles, which means a higher level of functioning than boys. Four out of seven median values in the dimension Social Interactive Organization, as well as the median value in the self-quieting item in the dimension State Regulation, were significantly higher for girls. The interquartile range of the items seemed wider for boys than for girls. Conclusions: The results indicate behavioral variability among healthy neonates. Gender differences were also observed with girls showing higher levels of functioning than boys. Key words: assessment; neonates; infant development; infant health.
Investigators have been attracted recently to the behavioral repertoire and functioning of the newborn infant. Despite many studies addressing the impact of prenatal events and the risks of prematurity, there are still many unanswered questions related to early prevention of later developmental difficul¨ and Gillberg ties. For example, according to Kadesjo (1998), children apparently are born healthy and develop dysfunctional behaviors later on. Scientists have stressed different requirements for successful development. Brazelton and Cramer All correspondence should be sent to Cristina Lundqvist, Department of Paediatrics, Bora˚s Hospital, 501 82 Bora˚s, Sweden. E-mail: cristina.
[email protected].
䉷 2000 Society of Pediatric Psychology
(1990) emphasized the importance of caring for the parent and infant as a unit since the infant develops within this system and suggested a transdisciplinary approach. Schore (1994) suggested that failures in the dyadic processes of affect regulation lead to developmental psychopathology. Many researchers (e.g., Nordberg, 1995) have demonstrated that the quality of social-interactive experiences has important implications for children’s mental development. Some researchers have focused on the baby’s contribution to this interactive process (Murray, 1994) whereas others have focused on the importance of the parents’ behaviors, especially the mother’s. Thompson (1990) stated the fundamental
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principle that others initially regulate emotions, but the baby, as development proceeds, becomes increasingly self-regulated because of neurophysiological maturation. With insights from clinical pediatrics, psychiatry, and developmental and clinical psychology, Brazelton and his colleagues (1973) constructed the Neonatal Behavioral Assessment Scale (NBAS) to demonstrate both positive and negative characteristics of behavior. In contrast to the pathological models evaluating deficits, Brazelton, Lester, and their colleagues (1976) considered the baby’s whole behavioral repertoire as an important factor in his or her development. The NBAS has been revised twice, in 1984 and 1995. The scale combines neurological items with an extended behavioral repertoire of the infant in an interactional process. It measures the coping capacities and adaptive strategies of the infant. The optimal interactional process is described as a condition wherein the newborn baby uses most of his or her energy to interact with the environment, has physiological control, and is controlling his or her motor activity and state (Brazelton, 1990). These integrative tasks proceed in a developmentally hierarchical manner with Autonomic Regulation preceding Motor Organization, followed by the task of State Regulation and finally Social Interaction (Als, 1982). Gender-based behavioral differences have been established in studies on young children. Trevarthen (1996) found that asymmetries in emotional and communicative gestures are seen earlier among girls. Lindahl and Heimann (1997) reported that among 9-month-old children mother-daughter dyads displayed significantly higher degrees of social proximity than mother-son dyads, measured through nine items focusing on both communication and social interaction. Nordberg, Rydelius, and ¨ m (1991) found that boys at 1 year and 4 Zetterstro years of age were more vulnerable to psychosocial stress. Davis and Emory (1995) found that boys had a lower threshold for stress reactivity. Gender-based differences have been found among certain groups of children with dysfunctional behaviors and diseases; that is, a higher percentage of boys have problems related to attention, perception, and motor ¨ & Gillberg, 1998). Also, more boys control (Kadesjo than girls die in Sudden Infant Death Syndrome (SIDS) (McLaughlin et al., 1995). The aim of this study was to explore whether the NBAS would detect behavioral variations in an optimally healthy group of Swedish newborn
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infants and whether such possible variations are gender-related. Specifically, we hypothesized that behavioral differences among newborn infants are gender-related.
Method Participants Thirty-eight neonates participated in this study (20 boys and 18 girls). The mean weight of the girls was 3455 g (SD ⫽ 396 g) and of the boys 3605 g (SD ⫽ 434 g). The mean length of the girls was 50.5 cm (SD ⫽ 1.5 cm) and of the boys 51.3 cm (SD ⫽ 2.0 cm). The mean gestational age at birth for the girls was 39.5 weeks (SD ⫽ 0.9) and for the boys 39.6 weeks (SD ⫽ 0.9). Gestational age was determined from the date of the last menstrual period and by ultrasound verification at 15–16 weeks of gestation. Procedure Very healthy infants were recruited for the study to reduce the impact of perinatal factors. Midwives at the maternity ward were asked to register healthy 3-day-old infants on the mornings of prespecified days. To be classified as “very healthy,” the baby had to fulfill certain requirements: (1) an Apgar score (Apgar, 1954) of at least eight points at 5 minutes; (2) the baby must not have been instrumentally delivered; (3) the baby must not have a twin; (4) the baby must have had a minimum gestational age of 37 weeks; (5) the baby must have had a birth weight of at least 2500 g yet not more than 4500 g; (6) the baby’s mother must not have been given any analgesics during labor. These infants were then checked in accordance to Kyllerman and Hagberg’s optimal health conditions, a modification of Prechtl’s optimal concept (Kyllerman & Hagberg, 1983). The optimal health conditions included prepartal, partal, and postpartal items. Examples of prepartal items are maternal age of 18–30 years, mother’s pregnancy number 4 or less, and no maternal disorders in pregnancy (infection, diabetes, surgery, anemia-Hb 8.0g/ml, etc.). Examples of partal items are amniotic fluid clear and no pathological labor (duration less than 1/2 or more than 24 hours). Examples of postpartal items are no apnea, no hypoglycemia, and blood sugar levels ⬍30 mg/100 ml. The postpartal items were recorded on the third day of life. Optimal health
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in this study was defined as scoring positive to all optimal conditions except the age of the mother (our upper limit is 35 years instead of 30 years). The infants were examined at 48–72 hours of age to minimize the influences of the delivery. The aim was to examine the baby at the midpoint between two meals. This goal was not always achieved since breastfed infants often are fed at irregular intervals. No more than three babies were examined per day and if there were more babies fulfilling the requirements that day, the ones examined were chosen consecutively. All parents gave their consent to the assessment. All of the babies were examined by one of the authors (CL), who has been trained and certified to be reliable in administering and scoring the NBAS by the Boston group at Harvard Medical School. The babies were examined in a small and quiet room, in daylight, and in the presence of at least one parent. Complete assessment was not possible for five of the infants. Three babies, one boy and two girls, woke up during the measurement of the responses decrement to light, rattle, bell, and tactile stimulation. One boy and one girl fell asleep during the orientation items. Materials The NBAS is a multidimensional, multi-item scale (Brazelton & Nugent, 1995). The basic score sheet includes 28 behavioral items, 18 reflex items, and 6 supplementary items. The supplementary items were constructed to measure the quality of the baby’s responsiveness, the help the examiner has to invest to get the infant’s optimal performance, and also the response of the examiner to the infants. In order to compare the evaluations of the infants’ behavior, the items that interact in similar ways have been grouped into seven clusters describing global functions, following Lester, Als, and Brazelton (1982). The clusters are as follows: (1) reflexes (e.g., plantar grasp, babinski, ankle tonus); (2) motor system (which includes tonus, motor maturity, pullto-sit, defensive movements and level of activity); (3) autonomic stability (which includes tremors, startles and skin color); (4) habituation (which includes response decrement to light, bell, and tactile stimulation); (5) social interactive organization (which includes animate and inanimate visual, auditory orientation items, and alertness); (6) range of states (which includes peak of excitement, rapidity of build-up, irritability, lability of states and the
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cluster); (7) regulation of states (which includes cuddliness, consolability, self-quieting activity, and hand-to-mouth activity). The interactive character of the scale distinguishes it from other assessments. It demands thorough knowledge of newborn babies and of an infant’s developmental course as well as examiner flexibility. Examiner training procedures contain both a training phase and a reliability phase. This study used two of the supplementary items, specifically examiner facilitation and examiner’s emotional response to that infant. These were chosen with regard to their theoretical connection to attachment behavior and also because neonatal social behavior with an examiner during the NBAS examination has been found to be related to neonatal social behavior with the mother and to maternal functional stimulation (Arco, DeMeis, Self, & Gutrecht, 1984). The behavioral items, including the supplementary items, are scored on 9-point scales, and reflexes are scored on a 4-point scale. The infant’s reflex score is the total number of diverging scores. In some of the behavioral items the end-point score 1 or 9 represents the optimal status of function, in others the central score of 5 represents it. The reason for this is that Brazelton did not want to give the baby a sum score, which may be misused. In this study the item scores have been transformed to labels (italicized numbers) representing an increased level of functioning, where 9 means a high level of functioning and 1 a very low level of functioning. The item consolability, which measures the number of maneuvers the examiner has to utilize in order to bring the baby to a quite state, may serve as an example. In that case, 1 point stands for the baby not being consolable at all and 9 points means that simply seeing the examiner’s face consoles the baby. The measurement level of data is ordinal, meaning that there is a defined rank order of the category levels, but the levels do not represent any mathematical values. Furthermore, there are no defined distances between adjacent levels. These properties mean that arithmetic that creates sum scores cannot be applied (Coste, Fermanian, & Venot, 1995). Analysis Since normal distribution of data was not assumed, median values and nonparametric statistical methods were used. Gender differences in the median
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values for each item of the clusters reflexes, autonomic system, motor system, habituation, state organization, state regulation, social interactive organization, and two of the supplementary items have been analyzed by applying the WilcoxonMann Whitney test. In order to obtain an overall significance level of at least .05, the p values within a cluster have been adjusted according to Holm’s (1979) multiple test procedure.
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Table I. Clusters and Behavioral Items Clusters
Boys
Girls
Reflexes Diverging score
4 (2–5)
3 (1–5)
Motor system General tone
5 (5–6)
5 (5–5)
Motor maturity
5 (5–6)
6 (5–6)
Pull to sit
6 (5–8)
8 (6–8)
Defensive movements
5 (5–6)
6 (5–6)
Activity level
4 (3–5)
5 (4–5)
Autonomic stability
Results Except the items startle, tremulousness, and most of the motor items, the other behavioral items had a wide interquartile range (see Table I). The median profiles of the girls were in general higher than those of the boys (see Table I). According to the Wilcoxon-Mann Whitney test, four median values in the social interactive organization cluster were significantly higher for girls (the orientation items animate auditory, p ⬍ .01; animate visual and auditory, p ⬍ .05; inanimate auditory, p ⬍ .05; inanimate visual and auditory, p ⬍ .01). Girls’ median value in the item self-quieting (cluster state regulation) was also significantly higher than that for boys ( p ⬍ .01). Further, most of the interquartile ranges of the items seemed wider for boys (see Table I).
Discussion The aim of this study was to explore whether the NBAS could discover behavioral differences among medically very healthy infants and demonstrate that a baby may be healthy and seem strong and robust yet may also be vulnerable. For example, even healthy babies may have difficulties in selfregulation and therefore be hard to interact with. The study indicated that the NBAS detects behavioral differences among optimally healthy infants. The fact that the supplementary items examiner facilitation and examiner’s emotional response had a wide interquartile range emphasized that babies of optimal health need different amounts of help to organize themselves and provoke different feelings. This in turn has an impact on the interactive processes, attachment behavior, and infant development (Murray, Fiori-Cowlley, Hooper, & Cooper, 1996). Further, the study confirmed the hypothesis that there are behavioral differences between girls
Tremulousness
8 (8–8)
8 (8–8)
Startles
8 (8–8)
8 (8–8)
Lability of skin color
5 (3–5)
5 (4–5)
Response decrement to light
6 (4–7)
6 (4–7)
Response decrement to rattle
4 (3–7)
5 (4–7)
Response decrement to bell
6 (3–7)
5 (5–6)
Response decrement to foot stimulation
5 (4–6)
5 (4–6)
Animate visual
3 (2–7)
6 (5–7)
Animate visual and auditory
5 (3–7)
7 (6–8)*
Inanimate visual
5 (3–7)
6 (4–7)
Habituation
Social interactive organization
Inanimate visual and auditory
4 (3–7)
8 (7–8)**
Animate auditory
4 (3–6)
7 (6–8)**
Inanimate auditory
4 (4–7)
7 (4–8)*
Alertness
5 (4–6)
6 (5–8)
Range of states Peak of excitement
3 (2–4)
4 (3–4)
Rapidity of build-up
5 (3–7)
5 (5–7)
Irritability
4 (2–6)
6 (5–8)
Lability of states
6 (4–8)
7 (6–8)
Cuddliness
4 (4–5)
5 (5–7)
Consolability
5 (2–6)
6 (5–7)
Self-quieting
4 (2–6)
6 (6–7)**
Hand to mouth
4 (2–7)
7 (5–8)
Regulation of states
Supplementary items Examiner facilitation
6 (4–7)
6 (5–8)
Examiner’s emotional response
5 (3–6)
6 (5–8)
The values represent median and interquartile ranges. *p ⬍ .05. **p ⬍ .01.
and boys. The girls had higher functioning scores, especially in the social interactive organization cluster. This result is in accordance with Trevarthen (1996) and points in the direction of gender-based behavioral differences as innate. Since a higher percentage of boys develop dysfunctional behaviors and are overrepresented among certain diseases, such as nervous disorders and lower respiratory tract infections (van den Bosch, Huygen, van den Hoogen, & van Weel, 1992), we suggest it would be
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valuable to further explore qualitative genderbased differences. As clinicians, we see a demand for a diagnostic instrument that discriminates between immaturity, stress effects, and individual characteristics in neonatal wards, maternity wards, and health care centers. It seems that the NBAS is a satisfactory tool in this work. The results of this study are parsimonious to previous research that has demonstrated the effectiveness of the NBAS (Brazelton & Nugent, 1995). Therefore, we suggest that the NBAS be used complementary to neurological and pediatric examination when specific questions about the baby exist and when the baby already has been identified as an infant at risk. Infants who show considerable deviations should be monitored with repeated assessments. A simplified and shorter screening instrument
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based on the NBAS, with which to identify healthy infants who are at risk for attachment disturbances and developmental disorders, is desirable. The latter builds the premises for the next study.
Acknowledgments This study was supported by grants from The First of May Flower Foundation, Sweden. Special thanks go to Dr. Elisabeth Svensson, Biostatistics Branch, ¨ teborg, SweChalmers University of Technology, Go den, for her support and professional advice. Received March 10, 1999; revisions received August 3, 1999, and October 22, 1999; accepted November 30, 1999
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