Effect of maternal soothing on infant stress response

The effect of maternal soothing to infant inoculation as well as everyday distress on infant cortisol and behavioral responses to stress was examined in two longitudinal samples of 55 and 74 infants, respectively, between 2 and 6 months of age. There was no evidence that maternal soothing was effective in reducing infants' cortisol or behavioral responses to stress. The absence of this relation occurred despite evidence for cross-time stability and cross-situation consistency in maternal soothing. That maternal soothing plays little role in lowering infant responses to stress leaves open the possibilities that other maternal behaviors may mediate children's distress or that infant temperament may be related to infant stress.     

Dampening of Adrenocortical Responses during Infancy: Normative Changes and Individual Differences

Changes in cortisol and behavioral responses were examined longitudinally in 83 infants (39 girls, 44 boys) tested at their well-baby exams with inoculations at 2, 4, 6, and 15 months (72 infants completed all testing). Another sample of 2-, 4-, and 6-month-olds ( n = 18 per age) received mock exams without inoculations to determine early developmental changes to the exam procedures. Behavioral distress was coded every 30 sec during the exam, a 5-min inoculation period, and a 20-min recovery period. Salivary cortisol was obtained upon arrival at the clinic and 25 min after the beginning of the inoculation period. To the exam-inoculation procedures, cortisol responses were high at 2 months, decreased significantly between 2 and 4 months, remained comparable between 4 and 6 months, and then declined again between 6 and 15 months. Between 6 and 15 months there was also a decrease in pretest cortisol. By 15 months, significant increases in cortisol from pre- to posttest were no longer observed for most infants. To the exam-only procedures, cortisol responses decreased between 2 and 4 months, and by 4 months most infants failed to show pre- to posttest increases in cortisol. Behavioral distress decreased between 2 and 6 months, but increased again at 15 months. While crying and cortisol were modestly correlated during the 2- to 6-month exam-inoculation procedures, at 15 months no significant correlations were obtained. Behavioral and hormonal reactions thus followed different ontogenetic paths and may provide different information about infant functioning. There was some evidence that the emergence of the circadian rhythm in cortisol might be related to the early decrease in cortisol response.     

Marital Conflict Predicts Mother-to-Infant Adrenocortical Transmission

Employing an experimental design, mother-to-infant transmission of stress was examined. Mothers (N = 117) were randomized to either have a positive or conflictual discussion with their marital partners, after which infants (age = 6 months) participated in a fear and frustration task. Saliva samples were collected to assess maternal cortisol responses to the discussion and infant cortisol responses to the challenge task. Results indicate maternal cortisol reactivity and recovery to the conflict (but not positive) discussion predicted infant cortisol reactivity to the infant challenge. Mothers’ positive affect during the discussion buffered, and intrusion during the free-play potentiated, mother-to-infant adrenocortical transmission. These findings advance our understanding of the social and contextual regulation of adrenocortical activity in early childhood.     

Adrenocortical activity and the Brazelton Neonatal Assessment Scale: moderating effects of the newborn's biomedical status

The Brazelton Neonatal Behavioral Assessment Scale with Kansas Supplement (NBAS-K) was administered midway between feedings to 60 newborns who were between 32 and 122 hours old. 35 of the newborns were classified as extremely healthy and normal (Subgroup I), whereas 25 (Subgroup II) were characterized by slight perinatal problems including gestational age 36-37 weeks or 42+ weeks, and fetal distress during labor. All of the newborns were healthy enough to be cared for in a healthy newborn, Level I nursery. Immediately following administration of the NBAS-K, a blood sample was obtained for plasma cortisol determination. Correlations between behavioral responding on the NBAS-K and levels of plasma cortisol revealed few significant relations for the sample as a whole. When the 2 subgroups were examined separately, a number of significant relations emerged. Newborns in Subgroup I who were more competent in their motor control and state regulation capacities as assessed by Lester's Cluster Scores for the NBAS-K exhibited higher levels of plasma cortisol. In contrast, newborns in Subgroup II who exhibited a greater adrenocortical response to the examination showed more behaviors indicative of high behavioral arousal and distress. This pattern of relations for Subgroup II appeared to be mediated by the number of hours that had elapsed since delivery. As postpartum time increased, the strength of the association between adrenocortical activity and behavioral arousal/distress decreased for Subgroup II. A systems theory approach is used to interpret the difference in patterns of correlations found for the 2 subgroups.     

Developmental Change in Infants' Responses to Stress

Infant stress responses to a well-baby physical examination and inoculation were observed longitudinally at 2, 4, and 6 months of age. In general, there were cortisol increases over base to the procedures. Cortisol level and cortisol response decreased with age. These data indicate a developmental shift in adrenocortical functioning between 2 and 6 months of age. Further evidence for this shift was seen in the stability of individual responses between 4 and 6 months of age. Individual differences in both cortisol and behavioral responses showed the most stability between these 2 ages. Moreover, diurnal variation in baseline cortisol level was present only at 6 months of age. While a sizable minority of infants showed stress-related cortisol decreases to the procedures at a given age, there was no evidence for cross-age consistency in individual infants showing these cortisol decreases.     

Reactivity and regulation in cortisol and behavioral responses to stress

This study examined relations between reactivity (i.e., peak response) and regulation (i.e., response dampening) in 6-month-old infants' cortisol and behavioral responses to inoculation (N = 62). Data showed that reactivity and regulation were unrelated for both cortisol and behavior. The independence of reactivity and regulation suggests that measures of both are needed to characterize infant cortisol or behavioral response to stress more completely. For both reactivity and regulation, cortisol and behavior were unrelated, suggesting that measures of both are needed to assess infant stress more adequately. There was considerable variation in the timing of the peak cortisol response, suggesting that obtaining only a single poststressor cortisol sample does not provide a sensitive measure of cortisol reactivity.     

Psychological factors capable of preventing the inhibition of antibody responses in separated infant monkeys

The capacity of infant squirrel monkeys to mount an antibody response to viral challenge was evaluated after removal from their mothers in several social and physical environments. Control and separated infants were injected with a benign virus, the bacteriophage X174, and levels of neutralizing antibody were assessed for 3 weeks. Infants separated alone in an unfamiliar environment showed a significant reduction in antibody levels as compared to control infants. Allowing infants to remain in the home environment, either alone or with peers, prevented this inhibition of antibody responses from occurring. Similarly, providing familiar peers in the novel environment facilitated the normal expression of antibody responses. These results indicate that the trauma of maternal separation is significantly reduced when infants are familiar with the separation environment or familiar social companions are available. The reduced antibody response was associated with the highest level of adrenal activation induced by the unfamiliar separation condition, but antibody titers and plasma cortisol levels could not be specifically correlated in individual infants.     

Effects of transitions to new child care classes on infant/toddler distress and behavior

Changes in distress and problem behaviors of 38 infants/toddlers were examined after children transitioned from familiar to new classrooms to look at effects of non-continuity of caregiver. Child's age, classroom quality, teacher sensitivity, and transitioning with a peer were examined as possible mediators. Results suggest that transitions were associated with increased distress, especially for younger children. In addition, although overall classroom quality was low, children in higher quality pre-transition classrooms showed more distress after transitioning than children in lower quality classrooms. Transitions were associated with decreased problem behaviors. Both distress and problem behaviors returned to pre-transition levels within 3 weeks. Teacher sensitivity and transitioning with a peer did not relate to distress or problem behaviors. These findings contribute evidence about immediate effects of infant/toddler transitions in child care. Future research should explore child, classroom, and teacher–child relationship variables that influence effects of continuity versus non-continuity of caregiver.     

The Effects of Morning Naps, Car Trips, and Maternal Separation on Adrenocortical Activity in Human Infants

3 studies of adrenocortical activity in healthy 9-month-old infants were conducted to examine unanticipated results obtained in previous research. In the first study, morning naps were examined and found to be associated with significant decreases in salivary cortisol. These decreases were followed by a significant return to prenap cortisol concentrations. In the second study, riding for 40 min in the car was also shown to significantly lower salivary cortisol concentrations. This effect was obtained both for infants who did and who did not sleep during the car trip. In the third study, the effect of 30 min of maternal separation in the laboratory on salivary cortisol was compared to the effect of 30 min of play with mother present. Separation resulted in significantly higher salivary cortisol concentrations as compared to play with mother present. In general, correlations between cortisol and behavior were found to be nonsignificant under conditions that did not produce stress elevations in cortisol, while less positive, more distressed behaviour was significantly correlated with cortisol under separation or stress conditions.     

Stress Reactivity and Self-Recognition

This study examined longitudinally whether early differences in reactivity to stress are related to self-recognition at 18 months of age. Adrenocortical and behavioral to Stress responses to routine inoculation at 2, and 4 months and at 6 and 18 months were obtained. Previous finding indicated a development shift in adrenocortical functioning by 6 months of age that included the emergence of stable individual differences in cortisol response from this point in development. Self-recognition was related to greater cortisol response and less rapid quieting at 6 to 18 months, whereas 2- to 4-month cortisol and quieting response did not differentiate self-recognizers and non-self-recognizators. These findings indicate a role for temperament differences in facilitating the emergence of self-recognition.     

Examining stress reactivity in neonates: relations between cortisol and behavior

The association between cortisol and behavioral reactivity to a medical heel stick and a neurobehavioral exam was examined in 100 healthy African American neonates, who have been underrepresented in this area of research. Using continuous measures, behavioral distress was associated with cortisol reactivity to both stressors. High levels of behavioral distress, however, were associated with cortisol reactivity only in response to the neurobehavioral exam. In contrast, low levels of behavioral distress were associated with cortisol reactivity only in response to the heel stick. The results highlight potentially important parameters for exploring the relation between biological and behavioral reactivity to stress such as the operationalization of behavioral distress and the context in which a stress response is elicited.     

Developmental Change in Infant Cortisol and Behavioral Response to Inoculation

Child Development, 1994, 65 , 1491–1502. Infant cortisol and behavioral responses to receiving 1 versus 2 inoculations on 1 pediatric office visit were observed at 2 and 6 months of age. Cortisol level (pre- plus postinoculation level) decreased with age, whereas cortisol response (post- minus preinoculation level) did not vary with age when the data were aggregated over infants showing a pre- to postinoculation cortisol increase and those showing a decrease. Nonetheless, for those infants who showed a cortisol increase, cortisol level and response decreased with age. Infants quieted faster at the older age. There was a moderate relation between quieting behavior and cortisol response, at least for infants who showed a pre- to postinoculation cortisol increase. These findings indicate a developmental trend for a decline over age in adrenocortical reactivity to inoculation for infants showing a cortisol release following the perturbation. Results were comparable whether infants received 1 or 2 inoculations.     

Behavioral and physiological responsivity, sleep, and patterns of daily cortisol production in infants with and without colic

To describe the behavioral and physiological responses associated with colic, the responses of 20 two-month-old infants with and 20 without colic were studied during a physical examination. Parents kept a diary of infant behaviors (including crying and fussing) for 3 days following the visit. Using Wessel, Cobb, Jackson, Harris, & Detwiler criteria, colic was defined as fussing/crying for 3 hr or more on each of the 3 days. Behavioral data coded by "blind" observers showed that during the physical exam, colic infants cried twice as much, cried more intensely, and were more inconsolable than were control infants. Despite these behavioral differences, heart rate, vagal tone, and cortisol measures indicated no appreciable difference in physiological responsivity for the two groups. At home, parents collected saliva cortisol samples at wakeup, midmorning, midafternoon, and evening for 2 days. In a finding similar to that shown by the laboratory data, the colic and control infants did not have different levels of daily average cortisol. These laboratory and home data provide no evidence of greater responsivity in the physiological substrate of difficult temperament for colic infants and are consistent with evidence of similarity in temperament once colic is resolved. At home, compared with control infants, colic infants did display a blunted rhythm in cortisol production. By diary, they also slept about 2 hr less per day than did control infants. Nighttime sleep was still significantly different when fussing/crying was statistically controlled. These data suggest that colic might be associated with a disruption or delay in the establishment of the circadian rhythm in activity of the hypothalamic-pituitary-adrenocortical axis and associated sleep-wake activity.     

The Relations of Children's Emotion Regulation to Their Vicarious Emotional Responses and Comforting Behaviors

The purpose of the present study was to examine the relations of children's emotional and behavioral regulation (as indexed by heart rate variability and coping styles) to their emotional and prosocial responses to a crying infant. Kindergarten and second-grade children's vicarious emotional responses (e.g., facial reactions and heart rate slope) and comforting behaviors were recorded while children heard a crying infant. The mothers of these children completed a measure designed to assess their children's coping responses when exposed to others in distress. It was found that children who were able to regulate their arousal (as assessed with heart rate variance) and typically responded instrumentally when exposed to others' needy states and conditions were relatively unlikely to become distressed and relatively likely to talk to and comfort the crying infant. Compared to boys, girls were found to be more responsive to the crying infant and were reported to engage in more direct, active coping responses when exposed to others in distress. The results are discussed in relation to research on emotion regulation and coping in interpersonal contexts.     

Antecedents of Maternal Sensitivity During Distressing Tasks: Integrating Attachment,Social Information Processing,and Psychobiological Perspectives

Predictors of maternal sensitivity to infant distress were examined among 259 primiparous mothers. The Adult Attachment Interview, self‐reports of personality and emotional functioning, and measures of physiological, emotional, and cognitive responses to videotapes of crying infants were administered prenatally. Maternal sensitivity was observed during three distress‐eliciting tasks when infants were 6 months old. Coherence of mind was directly associated with higher maternal sensitivity to distress. Mothers' heightened emotional risk was indirectly associated with lower sensitivity via mothers' self‐focused and negative processing of infant cry cues. Likewise, high physiological arousal accompanied by poor physiological regulation in response to infant crying was indirectly associated with lower maternal sensitivity to distress through mothers' self‐focused and negative processing of infant cry cues.     

Early Adverse Experiences and Repeated Wheezing From 6 to 30 Months of Age: Investigating the Roles of Hypothalamic–Pituitary–Adrenal Axis Functioning,Child Sex,and Caregiving Sensitivity

This study examined associations among early adversity, diurnal cortisol, child sex, and caregiver sensitivity at age 6 months in relation to wheezing in children (47% male) followed to 30 months. Analyses included 676 mother-child dyads, 393 of whom completed an observational caregiver sensitivity measure. Participants were primarily ethnic minorities (42.7% Black, 25.4% Hispanic); 22.1% of children had ≥ 1 wheezing episode. Higher adversity was associated with increased wheeze frequency and blunted diurnal cortisol slope. The indirect effect of adversity on wheezing through cortisol slope was significant for females, but not males. Higher caregiver sensitivity was protective against wheezing for males, but not females, with high cortisol. Findings suggest complex associations among adversity, cortisol, child sex, and caregiver sensitivity in predicting wheezing.     

Responses of Free-ranging Rhesus Monkeys to a Natural Form of Social Separation. I. Parallels with Mother-Infant Separation in Captivity

Observations of 23 free-ranging rhesus monkey infants on Cayo Santiago, Puerto Rico, indicated that mothers' first postpartum estrous periods were marked by large increases in the amount of time infants were separated from their mothers, by disturbances in mother-infant relationships, and by increases in infant distress behavior. When their mothers resumed mating, most infants showed signs of agitation; a few briefly showed indications of depression. Male infants responded to their mothers' resumption of mating by playing more, whereas females engaged in less play and more allogrooming. The results suggest ( a ) that basic parallels exist between the behavioral responses of rhesus infants to their mothers' resumption of mating in the field and to forcible separation from their mothers in captivity and ( b ) that early separation experiences may play a role in the normal development or manifestation of sex differences in behavior.     

Differential Effects of Maternal Sensitivity to Infant Distress and Nondistress on Social-Emotional Functioning

Associations between maternal sensitivity to infant distress and nondistress and infant social-emotional adjustment were examined in a subset of dyads from the NICHD Study of Early Child Care ( N = 376). Mothers reported on infant temperament at 1 and 6 months postpartum, and maternal sensitivity to distress and nondistress were observed at 6 months. Child behavior problems, social competence, and affect dysregulation were measured at 24 and 36 months. Maternal sensitivity to distress but not to nondistress was related to fewer behavioral problems and higher social competence. In addition, for temperamentally reactive infants, maternal sensitivity to distress was associated with less affect dysregulation. Sensitivity to nondistress only prevented affect dysregulation if sensitivity to distress was also high.     

Behavioral Organization in Newborns and Its Relation to Adrenocortical and Cardiac Activity

Spangler, Gottfried, and Scheubeck, Roswitha. Behavioral Organization in Newborns and Its Relation to Adrenocortical and Cardiac Activity. Child Development, 1993, 64 , 622–633. The aim of this study was to assess relations between behavioral organization and adrenocortical and cardiac activity in newborns. Twice during the neonatal period, the behavioral organization of 42 newborns, in terms of orientation and irritability, was assessed by the Neonatal Behavioral Assessment Scale (NBAS), and the newborns' cortisol response to the NBAS procedure was determined. In addition, cardiac activity was assessed during 1 of the NBAS. Whereas there were only inconsistent correlations between newborn irritability and the adrenocortical response during NBAS, low orientation was associated with a higher increase in cortisol in both of the assessments. In addition, orientation was predicted by basal cortisol level. High heart rates were associated with high irritability and low regulation of state, and, in addition, negative relations were indicated between orientation and heart rate variability. The findings support a coping model of biobehavioral relations in newborns.     

Children's emotions and behaviors in response to infants' cries

Infant crying can elicit in others both a range of emotions and contrasting behavioral reactions, such as altruistic caregiving versus aggression. Variations in reactions to young infants' cries were examined in 60 children ranging in age from late preschool to preadolescence. Each child over-heard either a preterm or a full-term tape-recorded cry from an adjacent room. Then a mother, carrying her infant, came looking for her (previously) "crying" infant's bottle. Later each child was interviewed after hearing a tape recording of a preterm and a full-term cry. Children's emotions and behaviors thus were assessed in response to simulated, real distresses and hypothetical representations of distress. Children's self-reports of empathy, their verbalized intentions to help, their actual helping responses, and observers' ratings of negative emotion were common responses to cries at all ages. In addition there were significant increases with age in prosocial, behavioral interventions. Expressions of negative emotion were inversely related to subsequent forms of prosocial behavior that required direct interaction with the infant. The emotions and behaviors of most children were not influenced by whether they heard preterm or full-term cries. They were, however, able to discriminate between such cries and some articulated "theories" about the impact of the cries on the listener.