The development of infants' circadian rest-activity rhythm and mothers' rhythm

In order to know when and how infants obtain their circadian sleep-wake rhythm, infants' developing circadian rest-activity rhythm and mothers' circadian rhythm in the postpartum period were examined using actigraph monitoring. The subjects were 11 primipara and their infants. Actigraphic recordings for the infants and their mothers were made over 3-5 continuous days during the 3rd, 6th, 9th and 12th weeks after birth. A 24-h peak on a mean autocorrelogram of the infants' movements was detected at the 3rd week. The infants' circadian rest-activity rhythm already existed in the 3rd week. The amplitude of this 24-h peak gradually increased from the 6th to 12th week. This may be useful as an index of the development of infants' circadian rest-activity rhythm. An 11-h peak was also observed at the 3rd week. This 11-h peak was thought to be a semi-circadian rhythm. Regarding the mothers, the amplitude of the 24-h peak on the mean autocorrelogram at the 3rd week was the smallest of all other weeks, and it became larger from the 3rd to 12th week. This meant that the mothers' circadian rhythm at the 3rd week was influenced by their interrupted sleep at night to take care of their infants. The mother-infant synchronization is probably the 1st factor in the entrainment of infants' circadian sleep-wake rhythm. In this study, we also propose a novel method for compensating for missing data in autocorrelogram analysis.     

Allomaternal vocal behavior in squirrel monkeys.

Three groups of squirrel monkeys, containing 1-3 infants (N = 7) and 4 adult females each, were observed weekly for the first 12 weeks of the infants' lives. Infants received approximately 100 vocalizations, mostly "caregiver" calls, per waking hour from their mothers and the other adult females with whom they were housed (allomothers). Mothers vocalized very little to their own infants during the first few weeks of life, when infants remain on the mother's back full-time. Instead, allomothers (who were often carrying their own dependent infants) vocalized copiously to others' very young infants. Infants responded vocally to these allomaternal caregiver calls as early as Day 1 but were less responsive to mothers. When infants began leaving the mothers' backs, mothers' rates of calling increased five-fold as they used caregiver calls to retrieve separated infants. Early vocalizing to infants involves them in their first social exchanges and is probably performed by allomothers rather than mothers because the infant rides dorsally in this genus.     

Psychological functioning of daughters of breast cancer patients. Part II: Characterizing the distressed daughter of the breast cancer patient.

Sixty daughters whose mothers had breast cancer were cross-sectionally studied. Daughters age 11-20 reported feeling significantly more uncomfortable about involvement in their mothers' illness than daughters age 20+. Daughters whose mothers died were more likely to report long-term life plan changes and role changes with their mothers during the mothers' illness. The Global Symptom Index was predicted by the daughter's perceived degree of involvement with her mother (during her mother's illness), current emotional resolution (about her mother's illness), and sexual satisfaction. Sexual satisfaction was predicted by role changes during the mother's illness, frequency of sexual relations, and a depression scale.     

Transfer of maternal specific cell-mediated immunity to the fetus.

The extent of specific cell-mediated immunity was measured in 67 consecutive newborns and their mothers. The stimulation index of blast transformation of the infants' lymphocytes in the presence of purified protein derivative, Candida extract and streptokinase was greater than 2.0 in 54%, 18% and 23% respectively. This was seen only in infants whose mothers' index was also greater than 2.0 to the same antigen. Leucocyte inhibition factor generated from lymphocytes of four babies in the presence of purified protein derivative inhibited migration of indicator cells over 50%; their stimulation index with purified protein derivative was greater than 2.0. Newborns have cell mediated immunity to the same antigens as their mothers, and this wanes during the first few months of life.     

Mothers' frontal EEG asymmetry in response to infant emotion states and mother-infant emotional availability, emotional experience, and internalizing symptoms

This study examined the links between mothers' frontal EEG asymmetry at rest and during videos of their 5- to 8-month-old infants expressing three emotion states (joy, anger/distress, and neutral interest), mother-infant emotional availability (EA) in the home, mothers' depressive and anxious symptoms, and mothers' emotional experience in response to infant emotion cues. Greater relative right frontal activity at rest was associated with greater maternal anxiety, but was unrelated to EA or mother-reported emotional experience in response to infant emotion cues. A shift toward greater relative right frontal activation in response to infant emotional stimuli was associated with lower maternal anxiety, greater mother-infant EA, and mothers' experience of sadness, concern, irritability, and the absence of joy in response to seeing their own infant in distress. These findings suggest that mothers' in the moment empathetic responding to their infant's emotions, indexed by a shift in frontal EEG asymmetry in response to infant emotional displays, is related to mother-infant EA in the home. Implications for conceptualizing parenting risk are discussed.     

Clonal diversity and turnover of Streptococcus mitis bv. 1 on shedding and nonshedding oral surfaces of human infants during the first year of life

Streptococcus mitis bv. 1 is a pioneer colonizer of the human oral cavity. Studies of its population dynamics within parents and their infants and within neonates have shown extensive diversity within and between subjects. We examined the genetic diversity and clonal turnover of S. mitis bv. 1 isolated from the cheeks, tongue, and primary incisors of four infants from birth to 1 year of age. In addition, we compared the clonotypes of S. mitis bv. 1 isolated from their mothers' saliva collected in parallel to determine whether the mother was the origin of the clones colonizing her infant. Of 859 isolates obtained from the infants, 568 were unique clones. Each of the surfaces examined, whether shedding or nonshedding, displayed the same degree of diversity. Among the four infants it was rare to detect the same clone colonizing more than one surface at a given visit. There was little evidence for persistence of clones, but when clones were isolated on multiple visits they were not always found on the same surface. A similar degree of clonal diversity of S. mitis bv. 1 was observed in the mothers' saliva as in their infants' mouths. Clones common to both infant and mothers' saliva were found infrequently suggesting that this is not the origin of the infants' clones. It is unclear whether mucosal immunity exerts the environmental pressure driving the genetic diversity and clonal turnover of S. mitis bv. 1, which may be mechanisms employed by this bacterium to evade immune elimination.     

Interventions with depressed mothers and their infants: modifying interactive behaviours

BACKGROUND: Postpartum depression (PPD) has a prevalence ranging from 3% to 30% and is associated with serious infant growth and developmental problems. Interventions directed at improving maternal mood have been unsuccessful in producing changes in observed face-to-face interactions between mother and infant. The Keys to Caregiving (KTC) is an intervention program that helps parents to understand and respond to infant behaviours, with a goal of increasing positive affective expressions in infants. In this pilot study, KTC was used with mothers suffering from mild to moderate PPD and their infants. METHODS: PPD was confirmed by scores on the Edinburgh Postnatal Depression Scale and the Beck Depression Inventory. Eleven dyads completed the study. KTC was carried out in 5 weekly group sessions, beginning at infant age of 3 months. Dyads were videotaped prior to and after KTC, using the Face-to-Face Still-Face paradigm, which assesses infants' responses during normal play and the effects of the Still-Face perturbation. The tapes were scored for infant facial emotion expressions. RESULTS: After intervention, infants displayed a marked increase in Interest and Joy when interacting face-to-face with their mothers, even though mothers' depression ratings did not change. LIMITATIONS: This pilot study is limited by lack of control dyads, however, it provides the foundation necessary for a full trial. CONCLUSIONS: This study suggests that intervention that focuses on what mothers do with their infants instead of how they feel can be effective in increasing infants' positive responsiveness and improving infant outcomes. Such interventions can be an essential component of treatment when mothers present with postpartum depression.     

Clonal Diversity and Turnover of Streptococcus mitis bv. 1 on Shedding and Nonshedding Oral Surfaces of Human Infants during the First Year of Life

Streptococcus mitis bv. 1 is a pioneer colonizer of the human oral cavity. Studies of its population dynamics within parents and their infants and within neonates have shown extensive diversity within and between subjects. We examined the genetic diversity and clonal turnover of S. mitis bv. 1 isolated from the cheeks, tongue, and primary incisors of four infants from birth to 1 year of age. In addition, we compared the clonotypes of S. mitis bv. 1 isolated from their mothers' saliva collected in parallel to determine whether the mother was the origin of the clones colonizing her infant. Of 859 isolates obtained from the infants, 568 were unique clones. Each of the surfaces examined, whether shedding or nonshedding, displayed the same degree of diversity. Among the four infants it was rare to detect the same clone colonizing more than one surface at a given visit. There was little evidence for persistence of clones, but when clones were isolated on multiple visits they were not always found on the same surface. A similar degree of clonal diversity of S. mitis bv. 1 was observed in the mothers' saliva as in their infants' mouths. Clones common to both infant and mothers' saliva were found infrequently suggesting that this is not the origin of the infants' clones. It is unclear whether mucosal immunity exerts the environmental pressure driving the genetic diversity and clonal turnover of S. mitis bv. 1, which may be mechanisms employed by this bacterium to evade immune elimination.     

Maternal touch and maternal child-directed speech: effects of depressed mood in the postnatal period

BACKGROUND: Postnatal depression affects the emotional state of mothers and the quality of mother-infant interaction. METHOD: Touch behaviour and content of child-directed speech were analysed for 72 mothers and their infants during pleasurable play. Infants (18) of mothers with depressed mood and 18 controls were seen when they were 6 months old; and 18 infants of mothers with depressed mood and 18 controls were seen when they were 10 months old. RESULTS: Depressed mothers in comparison with non-depressed mothers lifted their infants more, restraining their behaviours. Infants of depressed mothers in contrast to infants of non-depressed mothers spent greater periods of time in touching self rather than mother or toy, compensating for the lack of positive touch from their mothers. Mothers with depressed mood of 6-month-old infants included fewer affective and informative features in their speech than their controls. Non-depressed mothers of younger babies showed a higher use of affective features when compared with non-depressed mothers of older infants. In contrast, depressed mothers of 6- and 10-month-old babies showed similar frequencies of affect-salient speech during interactions in spite of their infants' changing developmental demands. LIMITATIONS: Mothers in this study were only mildly depressed, as assessed by the Edinburgh Postnatal Depression Scale (EPDS). Nevertheless, the findings indicate that mothers with depressive symptoms differ from non-depressed mothers in relation to touch and content of speech when interacting with their infants. CONCLUSIONS: These results suggest that postnatal depression may influence touch behaviour as well as the affective and informative content of maternal speech. The effect is that mothers with depressed mood in comparison with non-depressed mothers touch their infants more negatively and their speech is less well adjusted concerning the amount of emotional vs. information-related content thereby preventing depressed mothers from responding effectively to their infants' developmental needs.     

Early endotoxin exposure and atopy development in infants: results of a birth cohort study

BACKGROUND: Exposure to endotoxin in childhood is currently discussed to protect from the development of allergic diseases. OBJECTIVE: To study the effect of early endotoxin exposure on incidence of atopic sensitization, atopic dermatitis and wheezing until the age of 2 years in infants with different risk status in terms of parental atopy. METHODS: Data of 1942 infants of an ongoing birth cohort study were analysed by logistic regression. Endotoxin was measured in settled dust of the mothers' mattresses at infants' age of 3 months. Data on allergic symptoms and physicians' diagnoses were gathered by questionnaire. Sensitization to common food and inhalant allergens was assessed by specific serum IgE. RESULTS: High endotoxin levels increased the risk of repeated wheeze [adjusted odds ratio (OR) for 4th exposure quartile (Q4) 1.52, 95% confidence interval (CI) 1.08-2.14], but were associated with neither sensitization to food allergens nor atopic dermatitis. Stratification by parental atopy showed that there was an association of endotoxin exposure with incidence of repeated wheeze as well as with sensitization to inhalant allergens (P for trend = 0.008 and 0.044, respectively) only in infants with parental atopy, with the highest risk in the 4th exposure quartile (repeated wheeze: ORQ4 1.77, 95% CI 1.14-2.73; sensitization to inhalant allergens: ORQ4 1.69, 95% CI 0.70-4.11). CONCLUSION: Early endotoxin exposure in terms of mattress dust endotoxin levels seemed to increase the risk of atopic reactions to inhalant allergens at the age of 2 years, especially in infants at risk due to parental atopy. Our data disagree with an early protective effect of endotoxin on atopy development until the age of 2 years.     

The ontogeny of autonomic measures in 6- and 12-month-old infants

The purpose of this study was to develop a standardized protocol to measure preejection period (PEP), a measure of sympathetic nervous system, and respiratory sinus arrhythmia (RSA), a measure of parasympathetic nervous system, during resting and challenging states for 6- and 12-month-old infants and to determine developmental changes and individual stability of these measures. A 7-min reactivity protocol was administered to Latino infants at 6 months (n=194) and 12 months (n=181). Results showed: (1) it is feasible to measure PEP and RSA in infants, (2) the protocol elicited significant autonomic changes, (3) individual resting autonomic measures were moderately stable from 6 to 12 months, but reactivity measures were not stable, and (4) heart rate and RSA resting and challenge group means changed significantly from 6 to 12 months. Findings suggest that although infants' autonomic responses show developmental changes, individuals' rank order is stable from 6 to 12 months of age.     

Highly diverse TTV population in infants and their mothers

Infants born to serum HCV-positive 12 mothers were enrolled in the study. Nucleotide sequences amplified by primers deduced from a noncoding region were compared between mothers and their infants. The rates for detection of serum TTV in 12 mothers and their infants were 10/12 (83%) and 9/12 (75%), respectively. Serum TTV DNA was not detected in any infant at 1 month of age, but was detected for the first time between 1.5 and 8 months after birth. Positivity persisted thereafter throughout the follow-up period. In seven randomly selected mother-infant pairs, intrahost TTV heterogeneity was lower in infants than in mothers. Furthermore, one of seven mother-infant pairs showed a high degree of similarity (98.7-100%) in all clones, while in four infants, all nucleotide sequences differed by >10% from those of their mothers. However, the degree of homology in the two mother-infant pairs was 89-98.7% in family 2 and 88.1-99.4% in family 5. In the present study, with only one exception, it was shown that TTV from infants is not identical to TTV from mothers. The mechanism is discussed briefly in this paper.     

Severe maternal psychopathology and infant-mother attachment

Eighty-two mother-infant dyads, comprising women with psychiatric disorder and individually matched controls, were followed up over the children's 1st year of life. The mothers with mental illness consisted of two subgroups: first, 25 severely mentally ill mothers who had been admitted to a psychiatric unit with their infants; and second, 16 mothers from a community sample meeting research diagnostic criteria for unipolar, nonpsychotic depression. With the exception of six dyads in the in-patient group, observations were made of the mother-infant interaction and the quality of the infant-mother attachment relationship at 12 months. The nature and course of the mothers' illness was also documented. Although few residual symptoms of maternal mental illness were detected at 1 year postpartum, interactional disturbances were evident among the case group dyads. A strong association was revealed between infant-mother attachment quality and maternal diagnosis; a manic episode of illness in the postpartum period was related to security in the attachment relationship, and psychotic or nonpsychotic depression was related to insecurity. Concurrent patterns of mother-infant interaction provided support for this finding.     

Judgements of facial and vocal signs of emotion in infants with Down syndrome

We address how adults perceive facial and vocal signs of emotions in infants with and without Down syndrome. A set of naturalistic data from infants with trisomy 21 and typically developing infants (joy expression of young infants, 3.8-4.4 months, and anger and neutral expressions of older infants, 6.8-12.8 months) was rated by adult judges categorically or dimensionally. Facial signs alone, vocal signs alone, and both facial and vocal signs were presented for each expression. Raters were university students who did not have regular contact with infants, nor with people with mental retardation. Young infants' joy expressions were correctly recognized more frequently for typically developing infants than for infants with Down syndrome and, specifically, joy vocalizations in infants with Down syndrome were not identified. Facial signs were also more communicative than vocal signs in the case of older infants' anger and neutral expressions. These results are relevant to the way infant emotion is perceived by others, and may be particularly useful in facilitating interaction between adults and infants with Down syndrome.     

Discrimination between mothers' infant- and adult-directed speech using hidden Markov models

Infant-directed speech (IDS) has the important functions of capturing the infants' attention and maintaining communication between the mother and the infant. It is known that three acoustic components (F0, F0 range, and tempo) in IDS and adult-directed speech (ADS) are different. However, it is not easy to discriminate between IDS and ADS using procedural approaches due to the wide range of individual differences. In this paper, we propose a novel approach to discriminate between IDS and ADS that uses mel-frequency cepstral coefficient and a hidden Markov model-based speech discrimination algorithm; this approach is not based on the prosodic features of F0, F0 range, and tempo. The average discrimination accuracy of the proposed algorithm is 84.34%. The objective accuracy of the discrimination models have been confirmed using the head-turn preference procedure, which measures infants' listening duration to auditory stimuli of IDS and ADS. These results suggest that the proposed algorithm may enable a robust and reliable classification of mothers' speech and infant attention to the mothers' speech may depend on IDS clarity.     

Influence of gestational age and postnatal age on speech sound processing in NICU infants

The study examined the effect of gestational (GA) and postnatal (PNA) age on speech sound perception in infants. Auditory event-related potentials (ERPs) were recorded in response to speech sounds (syllables) in 50 infant NICU patients (born at 24-40 weeks gestation) prior to discharge. Efficiency of speech perception was quantified as absolute difference in mean amplitudes of ERPs in response to vowel (/a/-/u/) and consonant (/b/-/g/, /d/-/g/) contrasts within 150-250, 250-400, 400-700 ms after stimulus onset. Results indicated that both GA and PNA affected speech sound processing. These effects were more pronounced for consonant than vowel contrasts. Increasing PNA was associated with greater sound discrimination in infants born at or after 30 weeks GA, while minimal PNA-related changes were observed for infants with GA less than 30 weeks. Our findings suggest that a certain level of brain maturity at birth is necessary to benefit from postnatal experience in the first 4 months of life, and both gestational and postnatal ages need to be considered when evaluating infant brain responses.     

Infants' responses to the still-face situation at five and nine months: focusing on sex differences

This study investigated developmental changes and sex differences in infants' responses to a female stranger during a face-to-face interaction, still-face, and reunion phase. Twenty-two infants (11 boys and 11 girls) were observed at five and nine months of age. At five months, the infants smiled less in the still-face phase, while at nine months the infants smiled less at each subsequent phase. Girls, but not boys, smiled more at nine months than five months. Girls' gazing toward the social partner's face decreased during the still-face and reunion phases. Girls gazed toward the social partner's face more than the boys, independent of the phases and age. The findings support the view the effect of a still-face on infants is robust at both five and nine months and for both sexes. But the effect remained in the reunion phase only for the nine-month-olds. These findings suggest that girls have more interest in their social partner than boys.     

Developmental changes in the suckling behavior of hamster pups: a comparison with rat pups

The suckling behavior of hamster pups was observed to undergo several transitions during the preweaning period. Pups 10 days of age and younger attached to the nipples of their anesthetized mothers and suckled. After 10 days of age, however, only animals which had been deprived of suckling (and food and water) reliably attached to their mothers' nipples. By 25 days of age, deprived pups no longer suckled. The pattern of response after nipple attachment also changed during development: pups younger than 5 days of age remained on 1 nipple after initial attachment, whereas older pups shifted from 1 nipple to another. The development of suckling in hamster pups resembles that in rat pups, although certain changes or transitions occur at different ages in the 2 species. These changes may provide important markers for neural and behavioral development in each species and for comparisons between the two.     

The early relationship of drug abusing mothers and their infants: An assessment at eight to twelve months of age

Ten mother-infant dyads in which the mother abused drugs during pregnancy were compared to 10 matched drug-free dyads using a short form of the Parent-Child Early Relational Assessment to analyze videotaped mother-infant interactions. Interactions consisted of two five-minute segments: structured and unstructured play. Infants were 8–12 months of age. There was a consistent tendency for the drug abusing group mean scores to separate from the controls. Drug abusing dyads had significantly more (r = .71, Fisher's Exact Probability) ratings below 3.0 in the unstructured play situation for items that measured enthusiasm, responsivity to infant cues, and infant happiness. These categories provide preliminary evidence for those characteristics which may be most problematic in the relationship between drug abusing mothers and their infants, especially in situations in which mother is responsible for providing structure. © 1997 John Wiley & Sons, Inc. Inc.     

Parallels in stimulus-driven oscillatory brain responses to numerosity changes in adults and seven-month-old infants

Previous studies provide indirect evidence for an ontogenetically continuous Approximate-Number System. We employed a rapid steady-state visual-presentation paradigm combined with electroencephalography to measure stimulus-driven neural oscillatory responses to numerosities in infants and adults. Steady-state repetition of the same numerosity across a 2.4-sec time block yielded an increase in the stimulus-locked neural entrainment in both groups. Entrainment changes following a numerosity switch varied by the ratio of the numerosities, consistent with Weber's Law. These similarities thus provide direct evidence for an ontogenetically continuous Approximate-Number System. Moreover, the degree of neural entrainment significantly predicted infants' number discrimination measured behaviorally two months later.