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development, infant behaviors, premature infants



  1. Holditch-Davis, Diane
  2. Brandon, Debra H.
  3. Schwartz, Todd


Background: Although nurse clinicians and researchers use infant behaviors to indicate the responses of preterm infant to stimulation, little is known about how the biological factors of development, sleeping and waking states, infant characteristics, and infant illness severity affect preterm infant behaviors.


Objective: This study examined the development of eight infant behaviors over the preterm period and determined the relation of these behaviors to sleeping and waking and to infant characteristics and illness severity.


Methods: Seventy-one preterm infants were observed once per week from 7:00 p.m. to 11:00 p.m. from the time they were no longer critical until term or discharge. The occurrence of four sleep-wake states and eight behaviors were recorded every 10 seconds during the observations.


Results: Negative facial expressions increased over the preterm period; sighs, startle/jerks, jitters, and the likelihood of having hiccups decreased. Infant characteristics had only minor effects: boys had more negative facial expressions, and longer mechanical ventilation was associated with more sighs and jitters. All behaviors showed state-related differences in frequency. In addition, only startle/jerks and jitters showed the same developmental patterns within each state.


Conclusions: Significant development of infant behaviors occurs over the preterm period but involves changes not only in the absolute percentage of each behavior but also in the percentages within each sleeping and waking state. Thus, preterm infant behaviors cannot be used clinically for assessment without consideration of the state in which they occur.


Nurse clinicians and researchers use specific infant behaviors to indicate preterm infant responses to stimulation For example, changes in preterm behaviors have been used to identify acute medical complications, such as cold stress and sepsis (Holditch-Davis & Hudson, 1995) and pain (Walden et al., 2001). Researchers also used behaviors to show preterm infant responses to interventions that modified neonatal care so that it would be more developmentally appropriate (Chang, Anderson, & Lin, 2002). Clinicians have also used infant behaviors to indicate stress. However, there is little research validation for this. "Stress" behaviors did not differ between times when preterms were receiving routine and painful care (Grunau, Holsti, Whitfield, & Ling, 2000;Walden et al., 2001) and only occasionally differentiated the responses of preterm infants with and without chronic lung disease to handling (Medoff-Cooper, 1988).


Thus, a greater understanding of infant behaviors could strengthen the nursing care of preterm infants. According to the developmental science perspective (Cairns, Elder, & Costello, 1996), the infant and the environment form a complex system in which every behavior of the infant is a function of the entire system (Thoman, Acebo, & Becker, 1983). Subsystems within the infant, including maturation, physiological processes (e.g., sleeping and waking), and illnesses, affect the overall system and in turn are affected by it. Thus, the biological factors affecting infant behaviors as well as the environmental context of behaviors need to be examined. The purpose of this study, therefore, was to examine biological factors affecting eight preterm infant behaviors, specifically:


* development


* sleeping and waking


* infant characteristics


* illness severity.



The amount of infant behavior is known to change with age (Cioni & Prechtl, 1990). Sighs were less common in fullterm versus preterm infants (Hoch, Bernhard, & Hinsch, 1998). The likelihood of having hiccups decreased and mouth movements increased with age over the third trimester in fetuses (D'Elia, Pighetti, Moccia, & Santangelo, 2001;Pillai & James, 1990). The amount of large body movements did not show developmental changes over the preterm period in infants (Giganti et al., 2001;Hayes, Plante, Kumar, & Delivoria-Papadopoulos, 1992) but did decrease in fetuses, possibly due to decreased room to move in utero late in gestation (D'Elia et al., 2001;Kisilevsky, Hains, & Low, 1999). The development of other behaviors, including startles, jitters, and negative facial expressions, has not been examined. Moreover, most studies compared incidence of behaviors in individuals of different ages; only one examined developmental changes longitudinally (D'Elia et al., 2001). Only one study examined development in preterm infants (Hoch et al., 1998). Thus, little is known about developmental changes in infant behaviors over the preterm period, the time period of greatest interest to neonatal nurses.


Each behavior occurs primarily in a specific sleep-wake state. Sighs were more frequent in active sleep than quiet sleep in both fullterm and preterm infants (Hoch et al., 1998). Yawns and negative facial expressions were less common in quiet sleep than active sleep or waking states in near term fetuses and preterm infants (Giganti, Hayes, Akilesh, & Salzardo, 2002;van Woerden et al., 1988). In fullterm neonates, body movements occurred primarily in waking (Weggeman, Brown, Fulford, & Minns, 1987). Fullterm infants showed mouth movements and startles primarily in active sleep with rapid eye movements (REMs) (Korner, 1968), and startles were more common in sleeping, especially quiet sleep, than in waking states (Emory & Mapp, 1988;Huntington, Zeskind, & Weiseman, 1985;Korner, 1969). Conversely, hiccups were not related to any particular state in near term fetuses (van Woerden, 1989). The relationship between behaviors and sleep-wake states is strong enough that a number of behaviors are used to define sleep. However, not until at least 36 weeks postconceptional age do preterm infants show the same degree of correlation among these behaviors as fullterm infants (Curzi-Dascalova, Peirano, & Morel-Kahn, 1988). This suggests that both the amount of specific behaviors and the degree to which they are associated with particular sleep-wake states change with age.


The infant characteristics of sex and race have biological bases in the preterm period through prenatal hormones and the greater incidence of perinatal complications in minority infants (Johnson, 2000) and, thus, may affect infant behaviors. Although some researchers found no sex differences in fullterms in the amounts of large body movements, startles, and negative facial expressions (Korner, 1968;Weggemann et al., 1987), others have found that males show more startles (Korner, 1969). African American preterm infants had more jitters than Whites (Pressler & Hepworth, 2002), but racial effects on other infant behaviors have not been studied.


Likewise, illness may affect infant behaviors. Even mild perinatal complications were related to more jitteriness and changes in the incidence of startles in different states in fullterm and preterm infants (Emory & Mapp, 1988;Huntington et al., 1985;Parker et al., 1990). Preterms with chronic lung disease had more sighs and jitters than other preterms (Holditch-Davis & Lee, 1993). High-risk fetuses have fewer large body movements than low-risk fetuses (Kisilevsky et al., 1999). At 41 weeks postconceptional age, preterm infants had more large movements in active and quiet sleep and more facial movements in active sleep than fullterms (Booth, Leonard, & Thoman, 1980).


However, infant characteristics and illness severity effects on preterm infant behaviors have only rarely been studied along with development and sleep-wake states. Thus, how these factors jointly relate to preterm infant behaviors is unknown. The objectives of this study were to


* examine the development of eight infant behaviors over the preterm period


* determine how these behaviors relate to infant characteristics and illness severity


* examine the development of these behaviors within different sleep-wake states


* determine whether the relationships of these behaviors to infant characteristics and illness severity differs in different sleep-wake states


* determine whether the amounts of the behaviors are different in different sleep-wake states



Eight specific behaviors often observed by nurses were studied:


1. yawn


2. sigh


3. negative facial expressions


4. startle/jerk


5. jitter


6. large body movements


7. mouth movements


8. hiccups.



These behaviors were related to four sleeping and waking states, two infant characteristics (sex and race), and to several illness severity indicators (birthweight, length of mechanical ventilation [MV], and theophylline treatment). Birthweight and length of MV are known to be related to the neurologic status and developmental outcomes of preterm infants (Bhutta, Cleves, Casey, Cradock, & Anand, 2002;McCarton, Wallace, Divon, & Vaughm, 1996); whereas theophylline is a common medication that is known to affect sleeping and waking (Thoman et al., 1985).