Prematurity and respiratory illness: Brazelton scale (NBAS) performance of preterm infants with bronchopulmonary dysplasia (BPD), respiratory distress syndrome (RDS), or no respiratory illness

INFANT

BEHAVIOR

AND

DEVELOPMENT

15,

27-41

(1992)

Prematurity and Respiratory Illness: Brazelton Scale (NBAS) Performance of Preterm Infants With Bronchopulmonary Dysplasia (BPD), Respiratory Distress Syndrome (RDS), or No Respiratory Illness BARBARA Virginia

PATRICIA

Commonwealth

KATHRYN College

University

A. JARVIS AND GARY L. CREASEY Illinois

Medical

J. MYERS

of Virginia,

State University

W. KERKERING Virginia

Commonwealth

University

PHILIP I. MARKOWITZ Albert

Einstein

Hospital,

Philadelphia

AL M. BEST III Medical

College

of Virginia,

Virginia

Commonwealth

University

The aim of this study was to investigate how different levels of respiratory illness may influence the behavior of preterm infants on the Neonatol Behavioral Assessment Scale. Three groups were used: prematures with bronchopulmonary dysplasia (BPD; n = 14), respiratory distress syndrome (RDS; n = 17). and well prematures (n = 14). Across the three groups, infants did not differ in birth weight, gestotionol oge, and five demographic measures of mothers’ status: maritol status, race, age, education, and socioeconomic stotus. The BPD group performed more poorly on the NBAS interactive

This research was funded by a grant from the March of Dimes Birth Defects Foundation awarded to the first author. We would like to thank the infants and parents who took part in the study and the staff of the Medical College of Virginia Hospital for their helpful support. We thank the students who aided in aspects of data collection, including Gena Britt, Diane Lodder, Linda Parrish, Roger Rape, and Julie Resnik Marks. We also thank Chris Gennings who assisted with statistical analyses and Margaret Williams-Petersen and two anonymous reviewers for making helpful suggestions on the manuscript. An earlier version of this article was presented at the meeting of the Society for Research in Child Development, Toronto, Ontario, April 1985. Correspondence and requests for reprints should be sent to the first author at Department of Psychology, Virginia Commonwealth University, Richmond, VA 23284-2018.

27

28

MYERS,

JARVIS,

CREASEY,

KERKERING,

MARKOWITZ,

AND

and motor clusters. On several measures of degree of illness, the BPD more ill throughout the neonotal period thon the other two groups, ond “severity of illness” vorioble served OS an effective predictor of NBAS Family demographic meosures did not predict NBAS performance. The study confirm that degree of illness and medical complications and, respiratory illness, ore powerful contributors to the behavioral orgonization ture infants.

prematurity Brozelton

respiratory illness bronchopulmonary scale (Neonotol Behavioral Assessment

BEST

infants were a composite performonce. results of this specificolly, of prema-

dysplosio Scale)

Premature infants vary markedly in their illness status, from healthy preterms, whose primary need is to grow and mature, to infants who are beset with a long course of respiratory, neurological, sensory, feeding, and growth problems. Combining all premature infants of a similar weight or gestational age and treating them as a homogeneous group obscures this great variability. Indeed, illness status may be more important than birth weight or gestational age for predicting developmental outcome for the premature infant. The majority of studies reported in the psychological literature treat premature infants as a unified group and compare them as such with full-term controls. A number of studies, however, have classified their premature samples into groups according to type or degree of illness. Each of this handful of studies has used a different classification system. Divitto and Goldberg (1979) reported on the mother-infant interaction of subsamples of full terms, infants of diabetic mothers, healthy prematures, and sick prematures. Their “healthy” and “sick” premature groups were generic labels that comprised a wide spectrum of medical complications. Sostek, Quinn, and Davitt (1979) divided full terms and preterms into three classifications: healthy, ill without central nervous system (CNS) involvement, and ill with CNS involvement. The ill groups were divided according to neurological complications because of the assumption that CNS involvement has more traumatic effects than other medical problems. The ill groups were further divided into those who needed mechanical ventilation and those who did not. Greene, Fox, and Lewis (1983) used four groups of infants: healthy term, healthy preterm, sick full-term, and sick preterm. Their sick preterms suffered from respiratory distress syndrome (RDS), and the sick full terms experienced birth asphyxia during labor and delivery. The well groups, preterm and term, suffered no medical complications in the postnatal period. For Lasky et al. (1987), the criteria for group membership were birth weight (above and below 1500 gms) and requirement for mechanical ventilation. Holmes et al. (1982) divided their sample into groups of preterms, sick full terms, healthy full terms, and full terms who had prolonged hospitalization because their mothers were hospitalized. For each of these studies, division into illness-related subgroups gave a more precise description of infant development under varying conditions of health. For those studies which included

PREMATURITY

AND

RESPIRATORY

ILLNESS

29

both full-term and preterm groups, the effects of immaturity could be seParated from the effects of the illness. A more careful delineation by severity of illness helps to create a model for the respective contribution of various risk factors to infant development: immaturity, illness, complications, congenital abnormalities, and, potentially, environmental factors. The present study selected degree of respiratory illness as the criterion for categorizing a premature sample. Respiratory distress syndrome (RDS) is a lung disease resulting from inadequate surfactant in the newborn lung, most commonly the result of prematurity. For infants born weighing less than 2500 gms, the incidence of RDS is 10% to 15%. The incidence is inversely proportional to gestational age, with as many as 70% of infants born at 28 to 30 weeks being affected. Treatment is accomplished by the use of supplemental oxygen and ventilatory support. Although advances in perinatal-neonatal medicine have improved the outcome significantly, RDS remains a significant contributor to the morbility of preterm infants (Fanaroff & Martin, 1987). Chronic lung disease, or bronchopulmonary dysplasia (BPD), will develop in 10% to 20% of RDS infants overall, with as many as 70% of infants weighing less than 1000 gms at birth being affected. First described by Northway, Rosan, and Porter (1967), BPD is a chronic lung disease which develops as a sequela of long-term oxygen support and/or mechanical ventilation. The life-sustaining action of the ventilator and oxygen can eventually damage the lungs, compromising their ability to maintain adequate oxygenation and creating a chronic pulmonary condition. Infants with BPD may need supplemental oxygen and ventilatory support for many months, sometimes up to a year or longer (Sauve & Singhal, 1985). Growth is complicated by feeding difficulties and by higher caloric needs associated with the increased work of breathing. Growth problems persist at least into early childhood (Meisels, Plunkett, Roloff, Pasick, & Stiefel, 1986). These infants frequently develop other medical problems such as metabolic imbalance, infection, and pulmonary hypertension. Parents anticipating discharge may need to learn to perform medical caretaking functions such as percussion and postural drainage, suctioning, administration of oxygen, and cardiopulmonary resuscitation. At home, the BPD infant remains prone to respiratory infections and may require repeated hospitalizations in the first year of life (Sauve & Singhal, 1985). Markestad and Fitzhardinge (1981) noted that outcome for BPD infants is quite variable and depends on the subsequent perinatal and neonatal complications. In their sample of 26 infants with BPD, 23% died, one showed a major neurological handicap, and five had a combined Bayley score less than 85 at 2 years. The low Bayley scores were associated with a prolonged need for oxygen, longer hospitalizations, and recurrent apnea. Only six of the 20 survivors were above the 50th percentile for weight at 2 years. In a longer-term follow-up, the pulmonary function of 26 adolescents and young adults who had BPD in infancy was evaluated (Northway et al., 1990). TWO thirds of the BPD-affected young people still had some degree of

30

MYERS,

JARVIS,

CREASEY,

KERKERING,

MARKOWITZ,

AND

BESl

pulmonary dysfunction, consisting of airway obstruction, airway hyperreactivity, and hyperinflation; this high percentage was different from two control groups. Infants with BPD thus present medical and developmental challenges greater than those of infants with RDS alone. Both groups stand in contrast to well prematures, who, in spite of their need for long-term hospitalization, grow and mature and have a relatively uncomplicated medical and developmental course. This report is part of a longitudinal study of premature infants who are classified into BPD, RDS, and well-premature groups. This portion of the research reports on the three groups’ performance on the Neonatal Behavioral Assessment Scale (NBAS) at term age and the relation of the NBAS performance to demographic and medical variables. Studies using the NBAS that make comparisons across illness groups generally find some dimensions on which the most ill infants perform more poorly and some dimensions on which there are no differences across groups. Sostek et al. (1979) and Holmes et al. (1982) both analyzed their NBAS findings using the four a priori clusters (Als, 1978) and measured the infants at the time of hospital discharge. For Sostek et al., the motor cluster was worse for preterms than for full terms and also was rank-ordered according to illness group: It was poorest for ill infants with CNS difficulties, intermediate for ill infants without CNS difficulties, and best for the healthy infants. The state cluster tended to be worse for preterms than for full terms. For the stress cluster, prematures responded more poorly than full terms, with no significant differences between illness groups. The interactive cluster did not differ between groups. Holmes et al. found that performance on interactive and motoric processes was poorer for the two groups of infants with perinatal illness (preterms and sick full terms). Performance on state organization was better for the healthy full terms than for any of the groups with prolonged hospitalization (preterm, sick full term, and healthy full term with sick mothers). In the Greene et al. (1983) study, the NBAS data were analyzed using the Lester (Child Development Unit, Children’s Hospital Medical Center, Boston, MA) seven-cluster approach for main effects of healthy/sick and preterm/full term. Their infants were also assessed close to term age or at hospital discharge. Three of the seven clusters revealed main effects for health, with sick infants performing more poorly on the orientation, state regulation, and reflex dimensions. Three of the clusters showed a main effect for maturity, with preterm infants performing worse than full-term infants on the motor, autonomic, and reflex dimensions. In sum, the most consistent difference across these studies appears to be on the motor and state dimensions: The motor dimension was worse for the sickest preterms in the Sostek et al. and Holmes et al. studies and for the preterms in the Greene et al. study. The state clusters differed in Holmes et al. and Greene et al. and showed a tendency to differ in Sostek et al. An additional concern in any study of premature development must be the family characteristics and the home environment of the infant. As Sameroff

PREMATURITY

AND

RESPIRATORY

ILLNESS

31

and Chandler (1975) have modeled theoretically, the social class of the family works together with the medical status of the infant in an ever-changing way as the child grows and develops. Except for extreme conditions, the medical situation alone is not the only determinant of development but rather operates in a transactional manner with other influences in the child’s life. Numerous studies have demonstrated this. An example involving prematures is provided by Cohen and Parmelee (1983). Using 100 prematures who varied widely in social class and medical backgrounds, maternal education was the strongest single predictor of the Stanford Binet score at 5 years. These social class effects are seen more reliably as infants get older, and for the stillhospitalized infants in this study, no prediction was made for the effect of social class. Only demographic marker variables were available at this early point, not more complete measures of family and community influence. Nonetheless, to monitor whether these social class effects were apparent early on from the simple marker variables, the present study considered not only the infant’s illness but also family demographics, including mother’s age, education, marital status, race, and social class. The aim of this study was to investigate how different levels of respiratory illness may influence the behavior of preterm infants. Premature infants were classified by illness status into three groups: BPD, RDS, and well prematures. Several matching variables were used. As preterms’ status is powerfully affected by birth weight and gestational age, these two perinatal factors were matched as closely as possible across groups. The groups were also balanced for mother’s race, age, education, marital status, and social class. A number of measures of degree of illness were used to monitor how sick the infants were during the period from birth to term age. A central question was the contribution of degree of illness, above and beyond the diagnosis of BPD or RDS, to the infants’ performance on the NBAS at term age. The general hypothesis was that performance on the NBAS would be poorest for the BPD infants, and that infants with RDS would perform more poorly than the well prematures. Across groups, higher degrees of illness were predicted to have deleterious effects on NBAS performance. METHOD Subjects

Forty-five infants treated in a regional Neonatal Intensive Care Unit (NICU) during the years 1983 and 1984 participated in the study. The infants were classified by a neonatologist into three illness groups: (1) 14 preterms with BPD. Criteria for this diagnosis were: (a) primary lung disease requiring positive pressure ventilation within the first 3 days of life; (b) continued respiratory insufficiency because of pulmonary pathology requiring oxygen supplementation beyond 30 days of life; and (c) radiographic evidence of areas of focal emphysema and atelectasis persisting for at least 30 days. (2) The second group was 17 preterms with RDS who required mechanical

32

MYERS,

JARVIS,

CREASEY,

KERKERING,

MARKOWITZ,

AND

BEST

ventilation but whose illness did not progress to BPD. A diagnosis of RDS was made based on radiographic findings of air bronchograms, hypoaeration, and a ground-glass appearance to the parenchyma. (3) The third group was 13 preterms who did not have respiratory disease and whose hospital course was free of major medical complications (well prematures). Premature infants with only transient needs for oxygen without radiographic abnormalities were eligible for enrollment in the well-premature group; most had 0 to 2 days of oxygen, and two well infants received 6 days of oxygen. Premature infants in all groups were less than 38 weeks gestational age based on the Ballard assessment (Ballard, Kazmaier. & Driver, 1977) and were also less than 2500 gms. Excluded from all groups were infants with neurological abnormalities, serious (Grade III-IV) intraventricular hemorrhage, hydrocephalus, physical anomalies, genetic disorders, or other serious disorders unrelated to the diagnoses of RDS or BPD. Excluded also were infants whose mothers were under 17 years of age or those to be cared for by persons other than their natural parents. The three groups were equated for birth weight and gestational age and for five demographic measures of mother’s status: marital status, race, age, years of education, and socioeconomic status (SES) as measured by the Hollingshead Scale (Department of Sociology, Yale University, New Haven, CT). Due to a limited subject population, it was not possible to maintain an exact one-to-one matching of all these factors for specific infants across all three groups. Rather, an attempt was made to equate the groups on all of these. Every BPD infant who met the diagnostic criteria and whose parent gave consent was enrolled; RDS infants and well prematures who met the eligibility were enrolled based on the matching needs. Table 1 summarizes the sample characteristics. The three groups were not significantly different from each other on any of the matching variables. That is, as the matching procedure intended, groups did not differ significantly on birth weight, gestational age, or the maternal characteristics of marital status, race, age, education, or SES. Measures Medical Variables. The infants were rated at term age (40 weeks gestational age) on a variety of medical variables. These measures included three composite scales of medical problems: the Obstetric Complications Scale (OCS), the Postnatal Complications Scale (PCS; both Parmelee, Department of Pediatrics, School of Medicine, University of California, Los Angeles), and the Neonatal Morbidity Scale (NMS; Minde, Whitelaw, Brown, & Fitzhardinge, 1983). The OCS and PCS scales are widely used yes/no checklists of common medical risks, including such items as previous stillbirths, bleeding during pregnancy, and drug abuse (from the 40-item OCS) and convulsions, temperature disturbance, and infection (from the lo-item PCS).

PREMATURITY

AND

RESPIRATORY

TABLE Description

of Subjects:

Birth Weight, Contrasted

Moturify at Birth Birth weight (groms) M SD Gestotionol M

oge

Hollingsheod M SD

Demographics

Well n =

14

1326

1590

1564

504

567

311

F or x2

P

1.35

.27

30.6

31.2

32.4

2.6

2.9

1.8

1.64

.21

a 5

14 3

B 2

4.5”

34

a 6

12 5

5 a

3.1”

.21

24.0

25.9

26.0

0.63

254

4.5

2.9

7.9

13.0 2.4

12.6 1.9

12.3 2.7

0.35

.71

3.1 1.2

2.8 1.2

2.7 1.2

0.49

.61

age

SD Maternal M SD

RDS ” = 17

and

status

Rote White Block Maternal M

14

Age,

(weeks)

SD Demographics Moternal maritol Married Single

1

Gestotionol by Group

BPD n =

33

ILLNESS

education

Scale

(years)

(1 high,

5 low)

0x2.

The NMS includes 20 common diseases or pathophysiological states encountered among infants under 1500 gms. These are: convulsions, hydrocephalus, intracranial hemorrhage, perinatal asphyxia, diarrhea, necrotizing enterocolitis, meningitis, sepsis, pneumothorax, apnea, RDS, chronic lung disease, cardiac failure, hyperbilirubinemia, hypoglycemia, acidosis, bleeding tendency, anemia, nilper OS,and tracheostomy. Each condition is given a score of 0 if absent, 1 if mild, 2 if moderately severe, or 3 if severe. The NMS was modified in the following way: The measure asks for the infants to be rated daily on each of the 20 variables; for this study, we rated each infant just once, at term age, for the severity of that complication anytime since birth. In addition to these composite scales, infant medical variables included the following: Apgar scores at 1 and 5 min, days on mechanical ventilation, days on supplemental oxygen, days to full caloric intake by mouth, and days hospitalized. The variables that measured days were extended if needed beyond term age, continuing across the full NICU stay until initial discharge.

34

MYERS,

JARVIS,

CREASEY,

KERKERING,

MARKOWITZ,

AND

BEST

The composite medical variables (the OCS, PCS, and NMS) were rated by a neonatologist or developmental pediatrician at term age. Brazelfon Scale (NBAS). The NBAS (Brazelton, 1973, 1984) was administered by the first author, who is certified reliable on the exam, to all infants as close to term age (40 weeks gestational age) as possible or just prior to hospital discharge. The exams were administered in the NICU midway between feedings at the infant’s open crib or isolette. Some well prematures were tested 1 to 2 weeks earlier than term, as they were ready to be discharged from the hospital. Some BPD infants were tested 2 to 3 weeks later than term, as they were still medically unstable or confined to an oxygen hood at term age. The BPD infants were not tested until they were off the respirator and stable enough for testing; most were still on supplemental oxygen via nasal cannula. Thus, the well-group performance may be a slight underestimation of their true term-age performance, whereas the BPD-group performance may be an overestimation of average term-age BPD infant functioning. Given the hypotheses, these modifications were in a conservative. direction. The NBAS was used, as opposed to the APIB (Assessment of Preterm Infant’s Behavior; Als, Lester, Tronick, & Brazelton, 1980), because the infants in this study were not tested until they were of term age and required few, if any, medical supports. Thus, the NBAS, which is simpler to administer, was the appropriate examination. The examiner was, as much as possible, blind to infant’s group status. The only exceptions to blindness occurred with some infants in the BPD group, when supplemental oxygen and other signs of illness and extra medical attention were evident. The NBAS data were transformed into the four clusters recommended by the a priori clusters approach (Als, 1978). These clusters are interactive processes (which includes all the orientation items, alertness, cuddliness, and consolability); motoric processes (reflexes, general tonus. motor maturity, pull-to-sit, defensive movement, activity, and hand-to-mouth facility); state control (habituation items, peak of excitement, rapidity of build-up, irritability, lability of state, and self-quieting); and stress (tremors, startle, and lability of skin color). RESULTS Medical Variables The medical variables were analyzed using a one-way (Group) analysis of variance contrasting the three groups of premature infants. Results are presented in Table 2. The groups differed medically on most of the scales and measures. The mothers’ Obstetrical Complications Scale (OCS) scores were not different, but the infants differed significantly on both of the composite

PREMATURITY

AND

RESPIRATORY

TABLE Group

Comparisons BPD

Obstetric01

Complications

Complications

Morbidity

13

F

P

.15

6.4 3.5

5.6 2.7

1.98

5.2 1.1

4.2 1.5

2.4

10.21

.0003

11.3 3.1

6.4

2.5 3.7

26.58

.00001

4.4 2.0

4.9

6.6 2.3

3.59

.04

6.7 1.2

6.8 1.9

8.2

4.47

.02

23.0 19.0

3.6 4.6

0.15 0.3

16.90

.OOOl

141.9 71.5

11.9 14.9

1.2 0.9

51.20

.00001

111.5 57.1

30.9 20.5

14.1 11.4

27.55

.00001

134.7

47.7 33.7

25.8 33.7

38.57

.00001

2.2

Stole 2.9

1

SD

2.3

5

SD Days on ventilation M SD Doys on oxygen M SD Days to full caloric M SD Days hospitalized M SD

Well n =

Scale

SD

Awar, M

RDS n = 17

2.9

7.8

SD Neonotol M Apgor, M

14

Variables

Scale

M SD Postnatal M

2

of Medico1

” =

35

ILLNESS

intake

after

1.2

by mouth

birth 33.7

scales, the Postnatal Complications Scale (PCS) and the Neonatal Morbidity Scale (NMS). Infant groups also differed on their Apgar scores, days on ventilation, days on oxygen, days to full caloric intake by mouth, and days hospitalized. Specific contrasts between groups were performed using Tukey’s test at p < .05. As expected, the medical variables indicated that the BPD infants were the most ill. On the PCS, both the BPD and the RDS infant groups showed more complications than the well group; the BPD and RDS groups did not score differently. On the other composite scale, the NMS, all groups differed significantly from each other: BPD with the most neonatal complications, then RDS, then well. For the Apgar scores, the BPD infants scored lower at 1 min than the well infants, and lower than both the RDS and well groups at 5 min. For both days on the ventilator and days on oxygen, all three groups varied significantly from each other, with the BPD group showing the most days, then RDS, then the well group. (On these latter two variables,

36

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JARVIS,

CREASEY,

KERKERING,

MARKOWITZ,

AND

BESl

variances were not homogeneous, so square root transformations were made on the scores prior to performing the contrasts.) For both days to full caloric intake by mouth and days hospitalized, the BPD group required significantly more days than the other two groups, whereas the RDS and well groups did not differ from each other.

Performance

on the NBAS

Groups differed on two of the four NBAS clusters, interact and motor. Contrasts of the groups using Tukey’s test at p < .05 showed that the BPD group scored more poorly than the well group on the interact cluster and more poorly than both the RDS and well groups on the motor cluster. No other planned contrasts were significant. Performance on these clusters is shown in Table 3. Predicting

NBAS Cluster Scores

From Family Demographics. For all four NBAS clusters, none of the demographic marker variables (mother’s education, age, race, marital status, and social class) was a significant predictor in a regression model. Thus, as

TABLE A Priori

Cluster

Scores

on the NBAS BPD n =

Interactive” 1 (exceptionally

good)

StoteC 1 (exceptionolly

Groups

of Premature

RDS 14

n =

lnfonts

Well 17

” =

13

F

P

3.91

.03

0

0

1

3 11

8 9

8 5

good]

1 5 B

2 14 1

1 13 0

6.72

,003

good)

1.07

.35

0.41

.57

2 (adequate) 3 (deficient) MotoP 1 (exceptionally 2 (odequote) 3 (deficient)

3

of Three

2

5

2

2 (adequate) 3 (deficient)

B 4

10 2

8 4

Stress< 1 (adequate) 2 (deficient)

10 4

14 3

11 3

OControst using Tukey’s bControst using Tukey’s ‘No contrasts performed.

test test

at p < .05: at p < .05:

BPD group BPD group

worse worse

thon than

well group. well group

and

RDS group.

PREMATURITY

expected, demographic sample of infants.

AND

RESPIRATORY

ILLNESS

factors did not predict NBAS performance

37 for this

From Medical Variables: Creation of Principal Component Variable. Examination of the medical variables revealed that they were highly intercorrelated. This implies that if all of the medical variables were included as predictors in a multiple regression, problems of collinearity would result. Scores on the PCS, NMS, days on ventilator, days on oxygen, and days hospitalized accounted for 73% of the covariance between these variables. Therefore, a single variable was constructed using principal components analysis to describe the overall sickness of the infants. The first principal component, made up of the five variables listed above, was used as a single predictor variable, termed severity of illness. This first principal component was: -2.684 + .1633 PCS + .0859 NMS + .0282 days on ventilator + JO56 days on oxygen + .0081 days hospitalized. Only the first principal component was used in the analyses. Gestational age did not contribute to the variance in the severity of illness principal component; therefore, it was treated as a separate predictor. Group (BPD, RDS, or well premature) and birth weight were also used as separate predictors in the multiple regressions. Stepwise Multiple Regressions. Separate stepwise multiple-regression equations were created for each of the four NBAS clusters. The potential predictor variables in the stepwise regressions were: severity of illness (the principal component variable), gestational age, birth weight, and group. The model which was found to significantly predict the interact cluster, RZ = .30, F(3,39) = 5.56, p < .003, included the three variables severity of illness, p < .02, gestational age, p < .02, and birth weight, p < .02. As expected, these were in the direction of better interact cluster scores being predicted by higher gestational age, higher birth weight, and a lesser severity of illness. After these three variables were taken into account, group did not contribute further to the prediction of the interact cluster. For the motor cluster, scores could be predicted by either the single predictor of’group, R 2 = .24, F(2, 41) = 6.72, p < .003, or by the single predictor severity of illness, R2 = .18, F(1,41) = 8.78,~ < .005; infants with a more severe degree of illness had poorer motor scores. The two variables, group and severity of illness, were so highly intercorrelated that when one was taken into account, the other added no more variance. Neither gestational age nor birth weight entered the regressions as significant predictors for the motor cluster. There were no significant medical predictors of the state and stress clusters. As stated earlier, there were also no between-group differences in these clusters.

38

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JARVIS,

CREASEY,

KERKERING,

MARKOWITZ,

AND

BEST

DISCUSSION The results of this study confirm that degree of illness and medical comphcations, and, specifically, respiratory illness, are powerful contributors to the behavioral organization of premature infants. Although gestational age and birth weight did not differ significantly in the three samples of premature infants examined here, the BPD, RDS, and well prematures differed markedly in their behavior. In the present study, the behavioral differences were captured by the interactive and motor clusters of the NBAS. Infants with BPD scored more poorly on both the interactive and motor clusters. Interpretation of the interactive cluster score indicated that, on average, the BPD infants scored more poorly on items such as looking at and following faces, voices, and inanimate objects, and were less alert, cuddly, and consolable. From the motor cluster, the BPD infants scored more poorly on a cluster that included reflexes, general tonus, motor maturity, pull-to-sit, defensive movements, activity level, and hand-to-mouth. The RDS infants were generally intermediate on these cluster ratings. These results are consistent with findings of poorer performance for other groups of ill prematures on the interactive (Holmes et al., 1982) and motor clusters (Greene et al., 1983; Holmes et al., 1982; Sostek et al., 1979). No explanation is available for the lack of group difference for the state regulation and response to stress clusters. State regulation differences have been found in other studies (Greene et al., 1983; Holmes et al., 1982) with preterm infants; stress regulation was found to differ in just one such study (Sostek et al., 1979). Numerous measures of medical complications showed that the three groups were quite different in both severity and chronicity of illness. There were two composite scales of illness, the PCS and the NMS. On the PCS, the BPD infants were different from both other groups, whereas the RDS and well groups did not differ from each other. On the NMS, however, all three groups were significantly different, with a gradation in the expected direction. The NMS summary score brings together a host of very serious and sometimes life-threatening conditions which are common to NICU-treated premature infants and thus is a more sensitive measure of the severity and complexity of illness. Other medical variables were counts of “days”: days on the respirator, days on oxygen, days to full caloric intake by mouth, days in the hospital. Although these are simple measures, they capture the impact that these respiratory illnesses have on families who are counting the days until their infants can come home. The BPD infants, as expected, spent longer on ventilation and oxygen support, as they suffered lung damage. Their illness also affected their feeding and nutritional status: The BPD infants required more days of intravenous or gavage feeding. Their suck was less well organized, and, because so much energy was expended in breathing, they could not spare the energy needed to suck from a nipple. Whereas the well prema-

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tures spent, on average, 2 weeks, and the RDS prematures, 1 month, before taking all their calories by mouth, the BPD infants spent an average of 4 months before they could suck well enough to take all their formula from a bottle. The length of the hospitalization also varied widely among the three groups: The well prematures stayed in the hospital a mean of 4 weeks, the RDS infants, a mean of 7 weeks, and the BPD infants, a mean of almost 20 weeks. These differences in degree of illness predicted behavior on two of the four NBAS clusters, demonstrating that the duration and severity of illness affected behavior in this group of BPD infants. Both the interactive and the motor cluster scores were less optimal for premature infants experiencing significant illness in the newborn period as compared to preterm infants healthy from birth. These differences have the potential to affect behavioral organization and interaction with caretakers. Indeed, a study of motherinfant interactions with this sample of infants found that when they were older, the BPD infants had less optimal mother-infant interactions (Jan+, Myers, & Creasey, 1989). The BPD infants scored less adequately at both 4 and 8 months in interaction with their mothers during a play-teaching sequence, when compared to the RDS and well-premature groups. Mothers of these infants were less sensitive to cues, did not respond as well to signs of distress, and did less fostering of social-emotional growth. Both the infants and the mothers appeared to be contributing to the awkwardness and lack of synchrony in these interactions. As expected, infants’ behavior in this sample was not predicted by family demographic characteristics. This finding may seem at first to run contrary to a model encompassing transactions of both medical and family variables. The available family variables at this point were demographic markers: maternal age, marital status, race, education, and social class. No measures of family interaction or family functioning were available, and indeed, the infants had not yet been home to be influenced by their families and communities. Thus, this nonfinding does not threaten the model predicting influences of both medical and family variables. During this period of severe illness, the medical variables overwhelmed the influence that might be shown by simple family demographics. For infants who are born prematurely, efforts are needed to reduce the severity of their complicating illnesses. Medical advances will hopefully decrease the risk of developing BPD . One important advance which may reduce the incidence and severity of respiratory distress syndrome (and, potentially, bronchopulmonary dysplasia) involves experimental efforts using administration of bovine surfactant to the neonate’s lungs shortly after birth to hasten oxygenation (Enhoming et al., 1985; Hallman, Schneider, Merritt, & Gluck, 1981). Other efforts are directed at individualized behavioral-developmental approaches to care in the NICU which emphasize a reduction of stress and an increase in self-regulation for the neonate (Als et al., 1986). Positive results in

40

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CREASEY,

KERKERING,

MARKOWITZ,

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the Als et al. (1986) investigation included not only reduced respirator and oxygen dependency but, significantly, better mental and motor performance at 3, 6, and 9 months and better behavior during play at 9 months. Advances in care for low birth weight infants need to combine medical and developmental treatments which will reduce the incidence and severity of illness. In summary, premature infants’ degree of illness, in this case, respiratory illness, had a major influence on behavioral development. Illness status joined with the traditional measures of gestational age and birth weight in explaining the infants’ abilities. Furthermore, illness was a more important predictor than family demographics at this early stage. Efforts at decreasing the incidence of premature birth and its complications need to be expanded to reduce the behavioral effects in these infants. REFERENCES AIS, H. (1978). Assessing an assessment: Conceptual considerations, methodological issues, and a perspective on the future of the Neonatal Behavioral Assessment Scale. Monographs of the Society for Research in Child Development, 43(5-6, Serial No. 177). Als, H., Lawhon, G., Brown, E., Gibes, R., Duffy, F.H., McAnulty, G., & Blickman, J.G. (1986). Individualized behavioral and environmental care for the very low birth weight preterm infant at high risk for bronchopulmonary dysplasia: Neonatal intensive care unit and developmental outcome. Pediatrics, 78, 1123-1132. Als, H., Lester, B.M., Tronick, E.C., & Brazelton, T.B. (1980). Towards a research instrument for the Assessment of Preterm Infants’ Behavior (A.P.I.B.). In H.E. Fitzgerald, B.M. Lester, & M.W. Yogman (Eds.), Theory and research in behavioral pediatrics (Vol. 1). New York: Plenum. Ballard, J.L., Kazmaier, K., & Driver, M. (1977). A simplified assessment of gestational age. Pediatric

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Brazelton, T.B. (1973). Neonatal Behavioral Assessment Scale (Clinics in Developmental Medicine No. 50). London: Heineman. Brazelton, T.B. (1984). Neonafal Behavioral Assessment Scale (Clinics in Developmental Medicine No. 88). London: Blackwell Scientific Publications. Cohen, S.E., & Parmelee, A.H. (1983). Prediction of five-year Stanford-Binet scores in preterm infants. Child Development, 54, 185-193. Divitto, B., & Goldberg, S. (1979). The effects of newborn medical status on early parent-infant interaction. In T.M. Field, A. Sostek, S. Goldberg, & H.H. Shuman (Eds.), Infanfs born at risk. New York: Spectrum. Enhorning, G., Shennan, A., Pessinager, F.. Dunn, M., Chen, C.P., & Milligan. J. (1985). Prevention of neonatal respiratory distress syndrome by tracheal instillation of surfactant: A randomized clinical trial. Pediatrics, 76, 145-153. Fanaroff, A.A., & Martin, R.J. (1987). Neonatal-perinatal medicine: Diseases of the fetus and newborn. St. Louis, MO: C.V. Mosby. Greene, J.G., Fox, N.A., & Lewis, M. (1983). The relationship between neonatal characteristics and three-month mother-infant interaction in high-risk infants. Child Developmenr. 54, 1286-1296. Hallman, M., Schneider, H., Merritt, T.A., & Gluck, L. (1981). Human surfactant substitution. Pediatric Research, 16, 290a. Holmes, D.L., Nagy, J.N., Slaymaker, F., Sosnowski, R.J., Prinz, S.M., & Pasternak, J.F. (1982). Early influences of prematurity, illness, and prolonged hospitalization on infant behavior. Developmental Psychology, 18, 744-750.

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Jarvis, P.J., Myers, B.J., & Creasey, G.L. (1989). The effects of infants’ illness on mothers’ interactions with prematures at 4 and 8 months. 1nfanf Behavior and Development, 12, 25-35. Lasky, R.E., Tyson, J.E., Rosenfeld, C.R., Krasinski, D., Dowling, S., & Gant, N.F. (1987). Disappointing follow-up findings for indigent high-risk newborns. American Journal of Dkeuses in Children, 141, 100-105. Markestad, T., & Fitzhardinge, P.M. (1981). Growth and development in children recovering from bronchopulmonary dysplasia. Journal of Pediatrics, 98, 597-602. Meisels, S.J., Plunkett, J.W., Roloff, D.W., Pasick, P.L., & Stiefel, G.S. (1986). Growth and development of preterm infants with respiratory distress syndrome and bronchopulmonary dysplasia. Pediatrics, 77, 345-352. Minde, K., Whitelaw, A., Brown, J., & Fitzhardinge, P. (1983). The effect of neonatal complications in premature infants on early parent-infant interactions. Developmental Medicine and

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