Dynamics of oralrespiratory coordination in full-term and preterm infants: II. Continuing effects at 3 months post term

Thirty-two infants participating in a longitudinal study of the effects of premature birth on sucking and breathing were tested at 3 months post term. They were assigned at a previous test to either a healthy full-term, healthy preterm, or high risk preterm group on the basis of birth weight, postconceptional age at birth, and perinatal medical status. Positive and negative sucking pressure as well as chest and abdominal breathing movements were recorded during nutritive sucking. The high risk preterms used a simpler and more stable pattern of coordination between sucking and breathing, were more likely to interrupt breathing at milk onset, and produced longer phase lags between positive and negative sucking pressure.     

Effects of fluid delivery on the sucking response of the human newborn

Two experiments were conducted with human newborns to compare sucking behavior under nutritive and nonnutritive sucking conditions using several fixed-ratio schedules of reinforcement. Results showed that: (1) nutritive sucking produces higher over-all sucking rates but lower within-burst rates, (2) burst lengths are longer during nutritive than nonnutritive sucking, (3) fewer bursts per unit time occur during nutritive sucking, (4) fluid termination following nutritive sucking produces a sharp response decrement, suggestive of a negative contrast effect when compared with sucking rates under continuous no-fluid sucking. Response diminution occurs in the first 2–3 min of sucking under all conditions, reflecting the necessity of control comparisons in studies documenting sucking change under changing stimulus or reinforcement conditions.     

Effects of nutritive and non-nutritive sucking on infant heart rate variability during the first 6 months of life

The effects of eating on heart rate variability (HRV) differ between adults and newborns. This may reflect the impact of suckling on the overall psychophysiological and autonomic nervous system maturation. The purpose of the present study was to explore whether the reactions of HRV during feeding change towards the adult pattern during the first 6 months of life. In addition, the effects of non-nutritive and nutritive sucking on heart rate (HR) and HRV were compared. The participants were 23 infants on whom recordings were performed as newborns and at 6, 12 and 24 weeks old. Nutritive sucking caused an increase in HR and a decline in HRV. The results were consistent with previous reports of a decrease in high frequency components of HRV during feeding in newborns, reflecting a decrease in parasympathetic activity. This response was apparent in all four ages studied, and remained similar throughout the 6-month period. However, age as an independent factor seemed to influence both HR and HRV. Pacifier sucking had no significant effects on HRV at any age. The results demonstrate the physical strain that sucking imposes on the baby, with a specific autonomic nervous system response involved. We consider this response an essential part of the overall psychophysiological maturation of infants.     

Infants with colic: A study of maternal stress and anxiety

The purpose of this article is to broaden our understanding of colic and to explore the effects of infant colic both on the mother's stress level and on her anxiety about separation from her infant. A “colic” group of 20 mother-infant dyads was compared with a second, control “noncolic” group of equal size. Significant group differences in the amount of time the infants cried, fussed, and were in a quiet/awake state were found. Although no difference in maternal trait anxiety was found, mothers in the colic group reported higher levels of stress associated with their infants' crying behavior. This stress was inversely related to the amount of time the infants slept during a 24-hour period. Mothers in the colic group also expressed significantly greater anxiety about separating from their infants for short periods of time; but the lack of freedom was significantly less of a problem for them than it was for mothers in the noncolic group. We conclude that mothers of difficult infants are more anxious about being separated from their infants, but do not appear to feel “trapped” by their extra maternal duties.     

The organization of non-nutritive sucking in the premature infant

Changes in non-nutritive sucking contingent upon the repeated presentation of unpatterned and patterned light stimulation were examined in a sample of 18 premature infants. Stimulus contingent sucking change in chronologically younger infants tended to be somewhat shorter in duration than that of the chronologically older infants and showed stimulus contingent sucking acceleration as well as suppression. Evidence was also found for less orienting among infants showing abnormalities in their sucking behavior. No evidence for habituation was found in any subgroup. Possible factors contributing to the strength and nature of stimulus contingent non-nutritive sucking changes in infants are discussed.     

Neonatal sucking: Effects of quantity of the response-contingent fluid upon sucking rhythm and heart rate

The temporal organization of neonatal nutritive sucking and heart rate were studied in two consecutive 4-min periods to analyze the effects of two quantities of response-contingent fluid. One group of newborns experienced only the larger amount, a second experienced the smaller, and two other groups experienced both in counterbalanced order. Cumulative pausing time and intersuck intervals (sucking rate within bursts) were both affected by the amount of fluid delivered at each response. At the start of sucking bursts, heart rate accelerated to a stable level. Within-burst heart rates were higher with increased quantity of contingently delivered fluid. The results are discussed in relation to the distinction between nutritive and nonnutritive sucking and to previous findings on the effects of fluid sweetness upon sucking.     

Discrimination of color and pattern novelty in one-month human infants

Visual discrimination of novel colors and patterns by one-month infants was studied in two experiments where visual reinforcers were presented contingent upon infants' rate of nonnutritive, high-amplitude sucking. Discrimination was measured by recovery of sucking to the presentation of novel visual reinforcing stimuli following decrements in sucking to familiar visual stimuli. In Expt 1, following decrement to familiar stimuli, independent groups received either a change in color, pattern, both color and pattern, or no stimulus change. Reliable recovery was demonstrated for the three stimulus novelty groups relative to the no-change control. Experiment 2, employing achromatic visual reinforcers also showed reliable recovery to pattern change relative to no-change controls. These findings with one-month infants indicate discrimination between familiar and novel visual reinforcers on the basis of color and pattern differences and an increase due to novelty in the reinforcing effectiveness of visual stimuli. Individual subject differences in response decrement magnitude during familiarization were positively correlated with amount of response recovery to novelty.     

Sucking patterns are not predictive of further feeding development in healthy preterm infants

Preterm infants are at risk of experiencing difficulties in their feeding development. For a possible early identification of these, we examined the association between sucking patterns, assisted spoon feeding, and chewing skills in 40 healthy preterm infants, and the role of experience in the acquisition of these skills in a prospective longitudinal study. Sucking patterns were evaluated at 34, 37, and 44 weeks postmenstrual age (PMA), assisted spoon feeding was evaluated at 6, 9, and 12 months PMA, and chewing was evaluated at 9, 12, and 24 months PMA. Sucking patterns were rated using the Neonatal Oral Motor Assessment Scale, assisted spoon feeding was rated using the Observation List Spoon Feeding, and chewing was evaluated using the Mastication Observation and Evaluation Instrument.All infants showed progression in their oral motor skills during the study period, but not all demonstrated a stable progression of skills. Quality of sucking patterns was not associated with skill level achievement of assisted spoon feeding or with chewing. Length of experience in sucking was significantly associated with duration of supplemental tube feeding but not with the quality of the sucking pattern. Length of chewing experience was significantly associated with chewing abilities at 9 and 12 months PMA. No clinical characteristics were sufficiently predictive of oral motor skill development. Results show that sucking patterns are not predictive of subsequent feeding development in healthy preterm infants. The food consistency offered and the length of feeding experience influenced the acquisition and quality of oral motor skills differently.     

Family context of infantile colic

Psychological factors in families with a colicky baby were studied. A total of 59 families who had enrolled on the basis of information received at the postpartum wards in the city of Turku, Finland, were included in this study. In addition, 58 families with age-matched infants were selected as a control group. These families kept a diary of the infant's crying. Thirty-six infants fulfilled the criteria for severe colic. Twenty-three families with a baby who cried excessively but did not fulfill the criteria were defined as the moderate colic group. A semistructured family interview was carried out to assess the structure, communcation patterns, functioning, and affective tone of the families. Mothers and fathers were younger in the moderate colic group compared with parents in the other groups. In the moderate colic families, the infant was more often the first child than in the control families. On the other hand, neither the infant's gender nor the education of the parents was related to infant's crying. Organized family structure and strong parental coalition were more often present in the severe colic and control groups than in the moderate colic group. Increased family chaos was noted in this group. The severe and moderate colic families had more enmeshed individual boundaries. Generational boundaries were enmeshed in the moderate colic families. Communication patterns did not differ between the groups. The families with a severely or moderately crying baby were less flexible, had decreased ability to cope with daily activities, and showed less energy and vitality than the control families. Both the severe and moderate colic families expressed more anxiety and conflict compared to the control families. In conclusion, an association between infantile colic and psychological characteristics of the family was found. Moreover, the families with a moderately colicky infant had specific psychological features that differed from both the control families and those with severely colicky infants.     

Depressed mothers' newborns show less discrimination of other newborns' cry sounds

Newborns' crying in response to the cry of another newborn has been called an empathetic response. The purpose of this study was to determine whether newborns of depressed mothers showed the same response. Newborns of depressed and non-depressed mothers were presented with cry sounds of themselves or other infants, and their sucking and heart rate were recorded. The newborns of non-depressed mothers responded to the cry sounds of other infants with reduced sucking and decreased heart rate. In contrast, the newborns of depressed mothers did not show a change in their sucking or heart rate to the cry sounds of other infants. This lesser attentiveness/responsiveness to other infants' cry sounds may predict their later lack of empathy.     

Differential sucking by neonates of depressed versus non-depressed mothers

Forty-two neonates (M = 39-h old) of depressed and non-depressed mothers sucked on cold (50 °F) and warm (78 °F) nipples on alternating trials. Half the infants received the cold nipple on the first of the eight trials (20 s each) and the other half received the warm nipple first. Neonates of depressed mothers sucked twice as much as neonates of non-depressed mothers, suggesting arousal dysregulation, overactivity or greater hedonic behavior in the newborns of depressed mothers. Although the newborns did not show a preference for cold or warm nipples, a temperature order effect revealed that neonates who received the cold nipple on the first trial sucked significantly more on trials 2–8 than those who received the warm nipple on the first trial, suggesting that an initially cold nipple might elicit greater sucking. More research is needed on maternal mood effects and temperature of objects to determine how these factors affect neonatal sucking behaviors.     

Clinical,developmental and social aspects of infant crying and colic

Persistent unexplained infant crying in the first few months is a common source of distress for parents and is costly for the health services. The aim was to assess the merits of developmental and social conceptualizations of this phenomenon, compared to the clinical approach as represented by the concept of colic. From a community sample of 530 infants, 67 who met the ‘rule of threes’ definition of colic by fussing and crying for 3 or more hours per day at 4-5 weeks of age were chosen. To avoid confusion, these infants were called ‘persistent criers’. Groups of ‘evening criers’ (N = 38) and ‘moderate cries’ (N = 55) were also selected. These 160 infants were assessed by researcher measures of their consolability and by maternal diary measures of their amounts of fussing, crying and colic behaviour when 5-6 weeks old. The persistent and evening criers cried more than the moderate criers. However, irritable, ‘fussy’ behaviour was the predominant form of distress for all three groups of infants. Colic bouts–defined as ‘bouts of intense, unsoothable crying and other behaviour, perhaps due to stomach or bowel pain’–were rare even among the persistent criers and only 7% of these infants were found to be inconsolable. The results support growing evidence that normal infant developmental processes are central to this phenomenon. In addition, social interactions between infants and parents, and parental subjective variables, appear to be involved. Colic was distinguished as a rare and separate form of distress by the infants' mothers. Further evidence needs to determine whether colic is a distinct clinical phenomenon or an extreme degree of normal distress interpreted within a western cultural framework.     

Influence of auditory tempo on the endogenous rhythm of non-nutritive sucking

The aim of this study was to examine the perception of time in the first months of life. Does the perception of contextual temporal information (an auditory tempo) induce modifications in spontaneous motor behavior (in the present case, non-nutritive sucking behavior) at birth and at 2 months? Two auditory tempos were successively tested. The first was the same as the previously recorded spontaneous motor tempo (SMT); the second was 15% faster or 15% slower than the infant's SMT according to the group. Results showed that modification of the sucking tempo depended on age and contextual temporal information. Two-month-old infants were able to adapt their endogenous sucking rhythm to an external tempo if it was faster than their spontaneous rhythm. Results also confirmed that slowing down the sucking rate was difficult for both groups of infants. In sum, the results suggest that, to a certain extent, very young infants are sensitive to contextual modifications (which indicates that they perceive them). This study has thus identified certain features of the internal time base rate from birth which could help define a developmental internal clock model of contextual temporal processing.     

Discrimination of polysyllabic sequences by one- to four-month-old infants

The goal of this research was to ascertain the effects of suprasegmental parameters (fundamental frequency, amplitude, and duration) on discrimination of polysyllabic sequences by 1- to 4-month-old infants. A high-amplitude sucking procedure, with synthesized female speech, was used. Results indicate that young infants can discriminate the three-syllable sequences [marana] versus [malana] when suprasegmental characteristics typical of infant-directed speech emphasize the middle syllable. However, infants failed to demonstrate discrimination when adult-directed suprasegmentals were used and in several other experimental conditions in which prosodic parameters were manipulated. The pattern of results obtained in the six experiments suggests that the exaggerated suprasegmentals of infant-directed speech may function as a perceptual catalyst, facilitating discrimination by focusing the infant's attention on a distinctive syllable within polysyllabic sequences.     

Infants' discrimination of internal and external pattern elements

Human infants' discrimination of changes in internal and external elements of compound visual patterns was investigated in four experiments employing a familiarization-novelty paradigm in which visual reinforcing patterns were presented contingent upon rate of high-amplitude nonnutritive sucking. In Experiment 1, 4-month infants discriminated changes in the shape of internal, external and both internal and external figures. One-month infants discriminated external changes in both internal and external figures, but failed to show reliable response recovery when only internal figures were changed. Experiments 2 and 3 failed to explain the 1-month results on the basis of poor resolution of internal figures by showing comparable discrimination of small and large singly-presented figures and by failing to find improved internal discrimination with large separation between internal and external figures. In Experiment 4, 1-month infants showed response recovery to figure additions made adjacent to the initial figure, but not to internal additions. The results are interpreted in terms of attentiveness by young infants to external pattern elements and may indicate early processing of figure-ground information. The developmental differences observed suggest an increased breadth of attention to pattern elements.     

Colic: What's maternal mental health got to do with it?

Families can benefit when pediatric and mental health professionals have a greater appreciation of psychological and relational issues that arise in the course of caring for an infant with colic. The Infant Behavior, Cry, and Sleep Clinic is a multidisciplinary, clinical intervention for parents who identify infant crying as adversely affecting infant, parental, and/or family functioning. Pairing pediatric and mental health expertise provides parents with strategies to manage infant colic within a context that recognizes parental mental health needs. Clinical case material illustrates varying responses and degrees of psychological distress in mothers whose infants have colic. Treatment approaches to colic that take into account maternal mental health needs may contribute to more optimal infant, maternal, and family outcomes.     

Effects of auditory stimulation upon non-nutritive sucking by premature infants.

Changes in non-nutritive sucking contingent upon presentation of an auditory stimulus previously found capable of eliciting heart-rate acceleration was investigated in a sample of 24 premature infants. Across 30 10-sec. presentations of the stimulus, only transient changes in sucking rate during the first 6 trials were observed, and these effects obtained primarily for those infants showing few abnormalities in their non-nutritive sucking behavior. These results were discussed as reflecting possible differences in infants' attention associated with sucking pathology and the dependence of psychological assessment upon the specific response index used.     

Preference for infant-directed speech in preterm infants

The current study explores the effects of exposure to maternal voice on infant sucking in preterm infants. Twenty-four preterm infants averaging 35 weeks gestational age were divided randomly into two groups. A contingency between high-amplitude sucking and presentation of maternal voice was instituted for one group while the other group served as a yoked control. No significant differences were observed in sucking of the two groups, but the degree of pitch modulation of the maternal voice predicted an increase in the rate of infant sucking.     

Dynamics of oralrespiratory coordination in full-term and preterm infants: I. Comparisons at 38-40 weeks postconceptional age

This study compares the coordination of pacifier sucking and breathing between healthy full-term, low risk preterm, and high risk preterm infants at 38–40 weeks postconceptional age. High and low risk preterm infants did not differ in overall score on a neurobehavioral examination (NAPI), but infants in the high risk group differed from the others in breathing frequency and in the coordination of breathing and sucking rhythms. For infants in the high risk group, sucking had less influence on respiratory frequency and patterns of coordination between the frequencies of sucking and breathing were simpler. Oral–respiratory coordination may be a useful marker of infants at risk for later speech problems.     

Infantile colic and parental experiences

The study comprised two groups of 33 parents each, one whose infants were identified by parents as colicky during their first 3 months and one with non-colicky infants. Parents filled out a questionnaire with one set of questions about parental experiences when infants were 3 months old and a set of parallel questions concerning current experiences (infant age 8-11 months). The results showed that the 3-month situation was more negatively described with regard to both infant behaviour and parental experiences by the parents of colicky infants. For the current situation (8-11 months), there were no significant group differences, meaning that no long-lasting effects could be demonstrated. However, in the colic group amount of crying and difficulty in comforting during the colic period were significantly related to current parental satisfaction, which suggests that these aspects of infant behaviour and experienced parental competence are of importance also in a longer perspective.