Chronic stress in the mother-infant dyad: Maternal hair cortisol,infant salivary cortisol and interactional synchrony

Stress physiology is shaped by early experience, with enduring effects on health. The relation of chronic maternal physiological stress, as indexed by hair cortisol, to infants’ stress systems and to mother-infant interaction quality has not been established. We examined maternal hair and salivary cortisol, six-month-old infants’ salivary cortisol, and mother-infant interaction in 121 mother-infant dyads. High maternal hair cortisol was related to higher infant average salivary cortisol concentration. Maternal hair cortisol and bedtime salivary cortisol were both uniquely related to infant bedtime salivary cortisol. Mothers with higher hair cortisol were more intrusive and had lower positive engagement synchrony with their infants. Maternal intrusiveness moderated the association of maternal hair cortisol and infant salivary cortisol, such that maternal hair and infant average salivary cortisol were related only when mothers were more intrusive. Maternal chronic physiological stress may upregulate infants’ developing stress systems, particularly in the context of lower mother-infant interaction quality.     

Cortisol reactivity, maternal sensitivity, and learning in 3-month-old infants

This study investigated the effects of adrenocortical functioning on infant learning during an emotionally challenging event (brief separation from mother). We also explored possible relationships between maternal sensitivity and both infant and maternal cortisol reactivity during the learning/maternal separation episode. Sixty-three 3-month-olds and their mothers were videotaped for a 10 min normal interaction period, and mother-infant behavioral synchrony was measured using Isabella and Belsky's [Isabella, R. A., & Belsky, J. (1991). Interactional synchrony and the origins of infant-mother attachment: A replication study. Child Development, 62, 373-384] coding scheme. The percentage of synchronous behaviors served as a measure of maternal sensitivity. Learning and short-term memory involved relating the infant's mother's voice with a moving colored block in a preferential looking paradigm. Infants whose cortisol increased during the session showed no learning or memory, infants whose cortisol declined appeared to learn and remember the association, while infants whose cortisol did not change evidenced learning, but not memory for the voice/object correspondence. Sensitivity and cortisol reactivity were correlated for mothers, but not for infants. Infant and maternal cortisol values for the first sampling period were highly correlated, but their cortisol reactivity values were uncorrelated, supporting the notion that infants and mothers have coordinated adrenocortical functioning systems when physically together, but become uncoordinated during a separation/learning event.     

Synchrony,complexity and directiveness in mothers’ interactions with infants pre- and post-cochlear implantation

This study investigated effects of profound hearing loss on mother–infant interactions before and after cochlear implantation with a focus on maternal synchrony, complexity, and directiveness. Participants included two groups of mother–infant dyads: 9 dyads of mothers and infants with normal hearing; and 9 dyads of hearing mothers and infants with profound hearing loss. Dyads were observed at two time points: Time 1, scheduled to occur before cochlear implantation for infants with profound hearing loss (mean age = 13.6 months); and Time 2 (mean age = 23.3 months), scheduled to occur approximately six months after cochlear implantation. Hearing infants were age-matched to infants with hearing loss at both time points. Dependent variables included the proportion of maternal utterances that overlapped infant vocalizations, maternal mean length of utterance, infant word use, and combined maternal directives and prohibitions. Results showed mothers’ utterances overlapped the vocalizations of infants with hearing loss more often before cochlear implantation than after, mothers used less complex utterances with infants with cochlear implants compared to hearing peers (Time 2), and mothers of infants with profound hearing loss used frequent directives and prohibitions both before and after cochlear implantation. Together, mothers and infants adapted relatively quickly to infants’ access to cochlear implants, showing improved interactional synchrony, increased infant word use, and levels of maternal language complexity compatible with infants’ word use, all within seven months of cochlear implant activation.     

MATERNAL SELF‐REPORTED DEPRESSIVE SYMPTOMS AND MATERNAL CORTISOL LEVELS INTERACT TO PREDICT INFANT CORTISOL LEVELS

Three basic findings have emerged from research on maternal depressive symptoms and offspring hypothalamic–pituitary–adrenal functioning: (a) Mothers’ depressive symptoms are positively associated with their offsprings’ cortisol stress response, (b) numerous individual and interpersonal maternal characteristics moderate this association, and (c) maternal and infant cortisol levels are highly correlated. In combination, these findings have suggested that maternal cortisol levels may moderate the relation between maternal depressive symptoms and infant cortisol responsivity; the current study assessed this hypothesis. Participants were 297 mother–infant dyads who were recruited from the community. Maternal depressive symptoms were assessed via self‐report. Dyads participated in two differentially stressful infant challenges when infants were 16 and 17 months old. Mother and infant salivary cortisol was collected before and after challenges. Results indicate that maternal cortisol levels moderated associations between maternal depressive symptoms and infant cortisol levels across both challenges. Infants showed higher cortisol levels if their mothers had both higher depressive symptoms and higher cortisol levels, as compared to infants of mothers with higher depressive symptoms and lower cortisol, and to infants of mothers with lower depressive symptoms and either higher or lower cortisol levels. We discuss findings in relation to environmental and biological factors that may contribute to the intergenerational transmission of depressive symptoms.     

Correlation between maternal and infant cortisol varies by breastfeeding status

ObjectiveThe objective of this study was to examine associations of mother and infant salivary cortisol, measured three times over the course of a day, and assess whether these varied by breastfeeding status.MethodsWe conducted a cross-sectional study of 54 mothers and their infants aged 4–11 months. Mothers collected their own saliva and that of their infants upon awakening, 30 min after waking and at bedtime. Breastfeeding status was reported by mothers and cortisol level was measured in saliva in μg/dl using standard techniques. We used generalized linear models to evaluate relationships between maternal and infant cortisol levels, and assessed whether the relationship differed by breastfeeding status: formula only compared to partial and full breastfeeding, adjusting for infant sex, race, age, maternal education, and family income.ResultsThirty-four infants received formula only and 20 were either partially or fully breastfed. Breastfeeding was associated with higher household income, higher maternal education, and white race. Cortisol levels were higher among breastfed infants at all three time points. After adjustment, maternal cortisol levels were related with infant cortisol at bedtime only (regression estimate 0.06; 95% CI: 0.10, 1.1; p = 0.02). The adjusted association between bedtime maternal and infant cortisol was stronger among breastfeeding dyads than among formula-feeding dyads (regression estimate 1.0; 95% CI: 0.1, 2.0; p = 0.04 vs. 0.6; CI: −0.1, 1.3; p = 0.10). In addition, we assessed the influence of maternal education and household income in our adjusted model; income strengthened the observed association, whereas maternal education did not change the estimate.ConclusionsBreastfeeding mothers and infants had significant correlations for cortisol at bedtime, while formula-feeding dyads did not. These data suggest that several factors may contribute to cortisol synchrony observed in mother/infant dyads, including the transfer of cortisol in human milk, physical interaction such as skin-to-skin contact, and shared environment. In addition, our findings support household income as a possible contributor.     

Synchrony in mother-infant vocal interactions revealed through timed event sequences

This report extends a previous cross-cultural study of synchrony in mother-infant vocal interactions (Bornstein et al., 2015) to immigrant samples. Immigrant dyads from three cultures of origin (Japan, South Korea, South America) living in the same culture of destination (the United States) were compared to nonmigrant dyads in those same cultures of origin and to nonmigrant European American dyads living in the same culture of destination (the United States). This article highlights an underutilized analysis to assess synchrony in mother-infant interaction and extends cross-cultural research on mother-infant vocal interaction. Timing of onsets and offsets of maternal speech to infants and infant nondistress vocalizations were coded separately from 50-min recorded naturalistic observations of mothers and infants. Odds ratios were computed to analyze synchrony in mother-infant vocal interactions. Synchrony was analyzed in three ways -- contingency of timed event sequences, mean differences in contingency by acculturation level and within dyads, and coordination of responsiveness within dyads. Immigrant mothers were contingently responsive to their infants’ vocalizations, but only Korean immigrant infants were contingently responsive to their mothers’ vocalizations. For the Japanese and South American comparisons, immigrant mothers were more contingently responsive than their infants (but not robustly so for South American immigrants). For the Korean comparison, mean differences in contingent responsiveness were found among acculturation groups (culture of origin, immigrant, culture of destination), but not between mothers and infants. Immigrant dyads’ mean levels of responsiveness did not differ. Immigrant mothers’ and infants’ levels of responsiveness were coordinated. Strengths and flexibility of the timed event sequential analytic approach to assessing synchrony in mother-infant interactions are discussed, particularly for culturally diverse samples.     

Maternal soothing and infant stress responses: soothing, crying and adrenocortical activity during inoculation

The relation between maternal soothing and infant stress response during inoculation was examined in a sample of 37 mothers and their 3-month-old infants. The mothers' soothing and the infants' cry vocalizations and the mothers' and the infants' salivary cortisol level pre- and post-injection were analysed. There was a positive relation between infants' cry vocalization post-injection and maternal soothing pre- and post-injection. The sample was divided in two sub-groups depending on whether the mothers evidenced most soothing of the infants in the period before (Preparatory group; n=20) or after (Contingent group; n=17) the syringe injection. In the Preparatory group, the duration of infant cry vocalizations was related to amount of maternal soothing before and after the injection, while cry vocalizations in the Contingent group was related to amount of maternal soothing after the injection. The Contingent infants responded to the injection with a significant increase in cortisol, while there was no increase in the Preparatory infants. The Preparatory infants evidenced significantly longer duration of looking at the target stimuli in a visual marking task, suggesting greater difficulties in disengaging attention. These findings indicate that 3-month-olds' stress responses and their mothers' situational behaviour are mutually regulated.     

Maternal prenatal psychological distress and temperament in 1–4 month old infants – A study in a non-western population

In this longitudinal study, conducted in women attending antenatal visits at the obstetrics and gynecology clinic of a general hospital in Bangalore, India, we aimed to assess the relationship between prenatal distress in mothers, and maternal report of infant temperament at four months. 100 mothers with normal full term deliveries completed the General Health Questionnaire-28 item version (GHQ) in the third trimester and postnatally. Salivary cortisol and temperament (using the Early Infancy Temperament Questionnaire – EITQ) were assessed in their infants aged 1–4 months. In this study, maternal prenatal psychological distress was not significantly associated with maternal report of difficult temperament in infants. Infants of mothers who were a negative screen for psychological distress (GHQ < 7), n = 85 had higher scores on the adaptability and approach dimensions of temperament. Infant salivary cortisol was significantly higher in infants with higher intensity scores. These results introduce the possibility of cultural differences in the relationship between prenatal distress in the mother and infant temperament. These could be factors linked to child rearing practices or to the measures employed to study infant temperament. These findings derive from a small sample with few mothers with psychological distress, and need replication in a larger sample.     

Infant Emotion Regulation Strategy Moderates Relations between Self‐Reported Maternal Depressive Symptoms and Infant HPA Activity

Children of mothers with depressive symptoms often have high cortisol levels. Research shows that various child characteristics (e.g., attachment pattern, internalizing behaviours, and temperament) moderate this association. We suggest that these characteristics share common variance with emotion regulation strategy. Therefore, we examine infant emotion regulation strategy as a moderator of the association between maternal depressive symptoms and infant hypothalamic–pituitary–adrenal (HPA) function. We hypothesize that infants who utilize more independent emotion regulation strategies and have mothers who report higher depressive symptoms will exhibit elevated cortisol levels. Participants were 193 mothers and infants (15 months old) recruited from the community. Self‐reported maternal depressive symptoms were assessed. Infant independent regulatory behaviours (withdrawal, wandering away, distraction, scanning, orienting to another object) were coded in the context of a Toy Frustration Task. Infant cortisol was collected via saliva samples at baseline, +20, and +40 minutes. Results indicate that infant emotion regulation strategy moderates the relation between mothers' self‐reported depressive symptoms and infant total cortisol output (AUC_G) and cortisol reactivity (AUC_I). Infants who employed more independent regulatory behaviours and have mothers with higher depressive symptoms experience greater cortisol secretion. We discuss the findings in relation to parent‐infant interactions and the adaptive nature of emotion regulation strategies, as they relate to HPA regulatory capacities. Copyright © 2015 John Wiley & Sons, Ltd.     

Spouses' Cortisol Associations and Moderators: Testing Physiological Synchrony and Connectedness in Everyday Life

In this study, associations were examined between cortisol levels of wives and husbands in 47 heterosexual married couples. Both partners' salivary cortisol levels were measured at the same moments seven times a day on 2 typical weekdays. After accounting for the effects of the diurnal rhythm of cortisol and relevant control variables, dyadic hierarchical linear modeling indicated significant positive linkages between partners' cortisol levels, consistent with the hypothesized within‐couple physiological synchrony. Variables reflecting more (spousal presence) or less connectedness (loneliness, being alone) were also collected at the time of each cortisol sample. Results indicated that husbands' cortisol levels were higher at moments they reported feeling lonelier and lower at moments they were in the presence of their spouse. Wives' cortisol levels were higher at moments they were alone. In addition, wife–husband cortisol synchrony was stronger for husbands who spent relatively more time with their spouse across the study period—even after accounting for time spent with others in general. These findings suggest that marital partners evidence positive within‐couple cortisol associations, and that connectedness (particularly physical closeness) may underpin spouses' physiological synchrony.     

Early interactive behaviours in preterm infants and their mothers: Influences of maternal depressive symptomatology and neonatal birth weight

The study evaluated the quality of preterm infant–mother interactions, considering severity of birth weight (ELBW and VLBW) and maternal depression, compared to full term babies. 69 preterm infants (29 ELBW and 40 VLBW) and 80 full-term (FT) infants and their mothers were recruited. At 3 months of corrected age, the quality of mother–infant interaction was evaluated through Global Rating Scales; moreover, infant level of development and maternal depression were assessed through Griffith Development Mental Scales and Edinburgh Postnatal Depression Scale. Results showed adequate sensitivity in preterm infants’ mothers and higher involvement with their infants, compared to full term mothers, but ELBW ones exhibited an intrusive interactive pattern and a higher prevalence of depressive symptoms. The study underlined the relevance of paying special attention to both ELBW infants and their mothers, in order to support the parenting role and the co-construction of early interactions.     

The association between maternal interaction and infant cortisol stress reactivity among preterm and full term infants at 4 months adjusted age

The purpose of this study was to assess the association between maternal interactive behavior and infant cortisol stress reactivity in response to the Still Face paradigm (SF) in a cohort of four-month old infants (adjusted age) born preterm (<32 weeks gestation, N = 22) compared with infants born full term (>37 weeks gestation, N = 28). Infant cortisol reactivity was calculated as area under the curve (AUC) from baseline to the third cortisol sample (30 min post-SF) using the trapezoidal rule, while the percent of time mothers spent using a contingent interaction style was measured (0–100%) during episodes 1 (Play; baseline), 3 (Reunion#1), and 5 (Reunion#2) while mother-infant dyads participated in the SF paradigm. We hypothesized that because infants born preterm are at increased risk for dysregulation, they would show, compared to full-term infants, a blunted stress response, involving under-responsiveness. We found blunted cortisol stress reactivity among the preterm infants. We also found that mothers of preterm infants demonstrated less contingent maternal interaction during Renion#1 of the SF; and that contingent maternal interaction at Reunion#2 of the SF was protective against cortisol stress reactivity in response to the SF. However, we did not find that the influence of maternal interaction on cortisol reactivity was moderated by gestational age group (full term vs preterm): the association between contingent maternal interaction and stress reactivity was similar for both gestational groups across episodes. In order to improve self-regulation and longer term social and cognitive developmental outcomes in medically at-risk infants, future research is warranted to determine how these findings relate to infants’ stress reactions in naturalistic settings, and the directionality and temporal relationship between cortisol stress responses and maternal interactive behavior.     

Motherhood in adolescent mothers: Maternal attachment,mother–infant styles of interaction and emotion regulation at three months

Early motherhood is considered a risk factor for an adequate relationship between mother and infant and for the subsequent development of the infant. The principal aim of the study is to analyze micro-analytically the effect of motherhood in adolescence on the quality of mother–infant interaction and emotion regulation at three months, considering at the same time the effect of maternal attachment on these variables. Participants were 30 adolescent mother–infant dyads compared to 30 adult mother–infant dyads. At infant 3 months, mother–infant interaction was video-recorded and coded with a modified version of the Infant Caregiver Engagement Phases and the Adult Attachment Interview was administered to the mother. Analysis showed that adolescent mothers (vs. adult mothers) spent more time in negative engagement and their infants spent less time in positive engagement and more time in negative engagement. Adolescent mothers are also less involved in play with their infants than adult mothers. Adolescent mother–infant dyads (vs. adult mother–infant dyads) showed a greater duration of negative matches and spent less time in positive matches. Insecure adolescent mother–infant dyads (vs. insecure adult mother–infant dyads) demonstrated less involvement in play with objects and spent less time in positive matches. To sum up adolescent mother–infant dyads adopt styles of emotion regulation and interaction with objects which are less adequate than those of dyads with adult mothers. Insecure maternal attachment in dyads with adolescent mothers (vs. adult mother infant dyads) is more influential as risk factor.     

Extra-legal factors and product liability: The influence of mock jurors' demographic characteristics and intuitions about the cause of an injury

Two experiments were performed to investigate the role of extra-legal factors in a simulated product liability trial. In cases where the factual evidence was identical, subjects' liability judgments varied as a function of the case-specific factor of the alleged source of the plaintiffs injury. In deciding cases differently depending on the alleged cause, subjects relied on intuitions about what injury sources are more or less likely to cause a certain kind of injury. Juror-specific factors also influenced subjects' verdicts. There was no difference between students and non-students, but race and SEC—factors that are often correlated with student status—did affect subjects' verdicts. Low-SES and minority subjects were more likely to find the defendant liable than high-SES and white subjects. The results are considered in terms of general decision-making processes, and the implications for jury selection and mock jury research are discussed.     

Temperamental precursors of infant attachment with mothers and fathers

The degree to which parent sensitivity and infant temperament distinguish attachment classification was examined. Multilevel modeling was used to assess the effect of parent sensitivity and infant temperament on infant–mother and infant–father attachment. Data were collected from mothers, fathers, and their infants (N = 135) when the infant was 3-, 5-, 7-, 12-, and 14-months old. Temperament was measured using the Infant Behavior Questionnaire-Revised ( Gartstein & Rothbart, 2003); parent sensitivity was coded during the Still Face Paradigm ( Tronick, Als, Adamson, Wise, & Brazelton, 1978); attachment was coded using the Strange Situation ( Ainsworth, Blehar, Waters, & Wall, 1978). Results indicate that mothers and fathers were less sensitive with insecure-avoidant infants. Whereas only one difference was found for infant–mother attachment groups and temperament, five significant differences emerged for infant–father attachment groups, with the majority involving insecure-ambivalent attachment. Infants classified as ambivalent with fathers were higher in perceptual sensitivity and cuddliness and these infants also showed a greater increase in low-intensity pleasure over time compared with other infants. Results indicate the importance of both parent sensitivity and infant temperament, though operating in somewhat different ways, in the development of the infant–mother and infant–father attachment relationship.     

An experimental study on mother-infant skin-to-skin contact in full-terms

In premature infants, daily skin-to-skin contact (SSC) has various beneficial effects on the health of the infant and the mother. These beneficial effects might extend to full-term infants. This experimental within-subject study examines the immediate effects of SSC on full-terms’ cortisol physiology during SSC and subsequent physiological and behavioral reactions to a mild stressor (a bathing session). Additionally, the effects of SSC on the quality of maternal behavior are examined.Between 5 and 7 weeks postpartum, 17 full-term infant-mother dyads were visited at home twice. During one home visit, a bathing session was proceeded by 50 min of mother-infant SSC, while during the other visit the bathing session was proceeded by 50 min of the infant resting alone. The order of the home visits was counterbalanced. Infant salivary cortisol measures were taken to measure the cortisol response to the experimental condition (SSC versus solitary resting) and the bathing session. Furthermore, infant behavioral distress and the quality of maternal behavior during the bathing session were scored from videotapes.Two-way within-subject repeated measures ANOVA’s showed that, when compared to solitary resting, full-terms’ cortisol concentrations significantly decreased during SSC, followed by higher cortisol reactivity in response to the subsequent bathing session. No effects of SSC on infant behavioral distress and maternal caregiving behavior were found. Apparently, a single session of mother-infant SSC can affect infant cortisol physiology in full-term infants. Future SSC research is needed to investigate the neurobiological mechanisms and dose-response relations in full-term infants.     

Mutual touch during mother–infant face-to-face still-face interactions: Influences of interaction period and infant birth status

Contact behaviours such as touch, have been shown to be influential channels of nonverbal communication between mothers and infants. While existing research has examined the communicative roles of maternal or infant touch in isolation, mutual touch, whereby touching behaviours occur simultaneously between mothers and their infants, has yet to be examined. The present study was designed to investigate mutual touch during face-to-face interactions between mothers and their 5½-month-old fullterm (n = 40), very low birth weight/preterm (VLBW/preterm; n = 40) infants, and infants at psychosocial risk (n = 41). Objectives were to examine: (1) how the quantitative and qualitative aspects of touch employed by mothers and their infants varied across the normal periods of the still-face (SF) procedure, and (2) how these were associated with risk status. Mutual touch was systematically coded using the mother–infant touch scale. Interactions were found to largely consist of mutual touch and one-sided touch plus movement, highlighting that active touching is pervasive during mother–infant interactions. Consistent with the literature, while the SF period did not negatively affect the amount of mutual touch engaged in for mothers and their fullterm infants and mothers and their infants at psychosocial risk, it did for mothers and their VLBW/preterm infants. Together, results illuminate how both mothers and infants participate in shaping and co-regulating their interactions through the use of touch and underscore the contribution of examining the influence of birth status on mutual touch.     

When I move,you move: Associations between automatic and person-coded measures of infant-mother synchrony during free-play using virtual in-home data collection

The relationship between movement synchrony and global scores of behavioral synchrony were investigated during a naturalistic free-play between 33 infants (ages 12- to 24-months) and their mothers using a video-conferencing platform. We assessed movement synchrony by applying an automatic tool, motion-energy analysis (MEA), to the obtained video data. Dyadic movement synchrony was associated with higher levels of maternal sensitivity, infant involvement, dyadic reciprocity, and a child-led interaction pattern. This demonstrates the feasibility of using MEA as an automatic tool for assessing movement synchrony in mother-infant dyads and its application for investigating naturalistic at-home free play sessions in a remote setting.     

Hormonal sensitivity of preterm versus full-term infants to the effects of maternal depression

Comparisons were made of differences in the hormonal sensitivity of preterm versus full-term infants to maternal depression, as reflected in children's cortisol levels. In Study 1 (N=25), a comparison was made between preterm versus healthy full-term children. In Study 2 (N=80), a comparison was made between preterm infants and full-term infants with mild or moderate medical problems. Preterm infants were found to be highly reactive to maternal depression (as measured by the Beck Depression Inventory). That is, they demonstrated higher cortisol levels when paired with depressed mothers and lower cortisol levels when paired with non-depressed mothers. No equivalent effects were found for children who were full-term, even when they had experienced other medical problems at birth. It was concluded that premature infants are exceptionally sensitive to the "emotional climate" in their home environment. As a result, they may manifest very different hormonal outcomes--with implications for their later development.     

Cortisol response to behavior problems in FMR1 premutation mothers of adolescents and adults with fragile X syndrome: A diathesis-stress model

Mothers of adolescents and adults with fragile X syndrome (FXS) are faced with high levels of parenting stress. The extent to which mothers are negatively impacted by this stress, however, may be influenced by their own genetic status. The present study uses a diathesis-stress model to examine the ways in which a genetic vulnerability in mothers with the premutation of the FMR1 gene interacts with child-related environmental stress to predict their morning cortisol levels. Seventy-six mothers of an adolescent or adult with FXS participated in an 8-day telephone diary study in which they reported on the behavior problems of their son or daughter with FXS each day. We analyzed salivary cortisol collected from mothers at awakening and 30 minutes after awakening on 4 of these days. The results indicated that mothers with greater genetic vulnerability had a lower level of cortisol on mornings following days when their son or daughter with FXS manifested more episodes of behavior problems, whereas mothers with less genetic risk evinced the opposite pattern of higher morning cortisol in response to their child's behavior problems. This finding contributes to our understanding of gene-by-environment interactions and highlights the importance of interventions to alleviate parenting stress in mothers raising children with FXS.