Infant Cortisol Reactivity Research Articles

Perceived Maternal Stress During Pregnancy and Its Relation to Infant Stress Reactivity at 2 Days and 10 Months of Postnatal Life

Although the negative impact of maternal stress during pregnancy on stress reactivity in offspring is well documented in nonhuman animals, we know little about these relations in humans and their lasting effects. The authors examined the relation between perceived maternal stress during pregnancy and stability of infant stress reactivity across the first year of postnatal life in humans. Perceived maternal stress during pregnancy was measured in the immediate postpartum period and again at 10 months after delivery in 84 mothers and examined in relation to behavioral and neuroendocrine stress reactivity measures in their healthy, full-term infants. Salivary cortisol was collected between 24 to 48 hours of postnatal life in response to a heel stick and again at 10 months of age in response to a toy removal task in the same sample of infants. Behavioral reactivity was coded from direct observation during the toy removal task. Perceived maternal stress during pregnancy and neonatal cortisol reactivity each remained stable across the first 10 months of postnatal life. Maternal stress during pregnancy predicted infant cortisol reactivity at 2 days and 10 months after birth as well as behavioral reactivity at 10 months. Neonatal cortisol reactivity predicted 10-month behavioral reactivity. These preliminary findings suggest that maternal stress during pregnancy may negatively affect neonatal stress reactivity within 24 to 48 hours after birth, and these influences may persist through the first year of postnatal life.

Maternal prenatal anxiety, postnatal caregiving and infants' cortisol responses to the still‐face procedure

This study prospectively examined the separate and combined influences of maternal prenatal anxiety disorder and postnatal caregiving sensitivity on infants' salivary cortisol responses to the still-face procedure. Effects were assessed by measuring infant salivary cortisol upon arrival at the laboratory, and at 15-, 25-, and 40-min following the still-face procedure. Maternal symptoms of anxiety during the last 6 months of pregnancy were assessed using clinical diagnostic interview. Data analyses using linear mixed models were based on 88 women and their 7-month-old infants. Prenatal anxiety and maternal sensitivity emerged as independent, additive moderators of infant cortisol reactivity, F (3, 180) = 3.29, p = .02, F (3, 179) = 2.68, p = .05 respectively. Results were independent of maternal prenatal depression symptoms, and postnatal symptoms of anxiety and depression. Infants' stress-induced cortisol secretion patterns appear to relate not only to exposure to maternal prenatal anxiety, but also to maternal caregiving sensitivity, irrespective of prenatal psychological state.

Cortisol reactivity, maternal sensitivity, and infant preference for mother's familiar face and rhyme in 6‐month‐old infants

This study investigated how cortisol (stress) reactivity and mothers' behavioural sensitivity affect familiarity preferences in 6‐month‐old infants. Relations between sensitivity and stress were explored using saliva samples taken from mothers and infants before, and 20 min after, two preferential looking experiments. Photographs and voice recordings from infants' mothers were incorporated into standard visual preference tasks. Sensitivity was assessed by determining the degree of behavioural synchrony between mother and infant from a 10‐min interaction period preceding the preferential looking experiments. Results showed that decreasing infant cortisol reactivity and greater maternal sensitivity were associated with familiarity preferences for mother's face stimuli. For the experiment with voice stimuli, a sex difference was obtained in the relationship between the directionality of cortisol reactivity and familiarity preferences. Results are related to a parallel study with 3‐month‐old infants, and issues are discussed in terms of infants' developing emotional independence from mother.

Prenatal cocaine exposure and infant cortisol reactivity.

This study examined the effects of prenatal cocaine exposure on infant hypothalamic-pituitary-adrenal axis activity and reactivity at 7 months of infant age. Participants were 168 caregiver-infant dyads (87 cocaine exposed, 81 not cocaine exposed; 47% boys). Maternal behavior, caregiving instability, and infant growth and behavior were assessed, and children's saliva was sampled before, during, and after standardized procedures designed to elicit emotional arousal. Results revealed cocaine-exposed infants had a high amplitude trajectory of cortisol reactivity compared to non-cocaine-exposed infants. Infant gender and caregiving instability moderated this association. The findings support a dual hazard vulnerability model and have implications for evolutionary-developmental theories of individual differences in biological sensitivity to context.

Maternal depression and infant cortisol: influences of timing, comorbidity and treatment

The current study examines the relationship between maternal depression and infant cortisol concentrations. The potential roles of comorbid maternal anxiety disorders, timing of maternal depression, and maternal treatment with psychotropic medications during pregnancy are addressed. Women with 6-month-old infants (105 boys and 84 girls) participated in a laboratory paradigm that included infant saliva collection at six points, noise burst and arm restraint stressor tasks, and a diagnostic interview of the mother. Lifetime history of maternal depression was associated with increased baseline and mean (average) infant cortisol levels. Comorbidity with anxiety disorder was related to infant cortisol reactivity. Peripartum (prepartum and/or postpartum) maternal depression, rather than a pre-pregnancy history of disorder, was associated with higher infant cortisol reactivity. Prenatal and postnatal exposure to maternal disorder had similar effects, but prenatal maternal psychotropic medication treatment appeared to attenuate infant cortisol increases associated with prenatal maternal disorder exposure. These data suggest that exposure to maternal depression and anxiety during pregnancy and the postpartum period may increase infant salivary cortisol. This maternal depression-infant cortisol association is independent of the effects of delivery complications, and appears to be modulated by prenatal maternal psychotropic treatment.

The association between prenatal exposure to cigarettes and cortisol reactivity and regulation in 7-month-old infants.

We examined the association between prenatal exposure to cigarettes and adrenocortical responses to stress in 7-month-old infants. Cortisol levels were assessed twice prior to and twice following affect-eliciting procedures in 111 (59 exposed and 52 nonexposed) infants. Cortisol reactivity was defined as the difference between the peak poststressor cortisol level and the pretask cortisol level. Higher values indicated higher cortisol reactivity. Exposed infants had higher peak cortisol reactivity than nonexposed infants. There were no differences in pretask cortisol levels. Maternal hostility mediated the association between cigarette exposure and peak cortisol reactivity. Furthermore, infant gender moderated this association such that exposed boys had significantly higher peak cortisol reactivity than nonexposed infants or exposed girls. These findings provide additional evidence that prenatal cigarette exposure is associated with dysregulation during infancy and that early adverse, nonsocial experiences may have relatively long-lasting effects on cortisol reactivity in infants.

Childbirth complications affect young infants’ behavior

The process of childbirth and its complications have been related to the newborn's condition and to development at later ages. In this study, we examine how mode of delivery and delivery complications are related to the behavior and cortisol reactivity of infants during the first 2 months. Delivery factors (i.e. mode, duration, fetal heart function, and 5-min Apgar score) were determined in 116 healthy, term, firstborn infants. The infants' behavioral and cortisol reactivity to stressors were assessed during a physical examination at 11 days and an inoculation at 2 months. Daily behavior at 6 weeks was followed by means of a four-day parental diary. Indicators of a more stressful delivery were linked to more crying/fussing in the infant and to more difficulties in regulating the infants' behavior (i.e., more unsoothability and longer crying bouts). Specific delivery complications rather than mode of delivery were linked to infants' behavior. No significant associations however, were found between childbirth and the infants' cortisol reactivity to a physical examination and an inoculation. Childbirth complications, even when mild, can apparently affect early infant behavior. These effects extend over different types of situations, and last at least until the age of 2 months, and should be taken into account in studies on infant behavior. Earlier findings of relations between childbirth complications and infant cortisol reactivity could not be replicated in this study, possibly due to the confounding effect of parity, and to the important intra-individual variability present in the infants' cortisol.

Neonatal procedural pain exposure predicts lower cortisol and behavioral reactivity in preterm infants in the NICU

Data from animal models indicate that neonatal stress or pain can permanently alter subsequent behavioral and/or physiological reactivity to stressors. However, cumulative effects of pain related to acute procedures in the neonatal intensive care unit (NICU) on later stress and/or pain reactivity has received limited attention. The objective of this study is to examine relationships between prior neonatal pain exposure (number of skin breaking procedures), and subsequent stress and pain reactivity in preterm infants in the NICU. Eighty-seven preterm infants were studied at 32 (±1 weeks) postconceptional age (PCA). Infants who received analgesia or sedation in the 72 h prior to each study, or any postnatal dexamethasone, were excluded. Outcomes were infant responses to two different stressors studied on separate days in a repeated measures randomized crossover design: (1) plasma cortisol to stress of a fixed series of nursing procedures; (2) behavioral (Neonatal Facial Coding System; NFCS) and cardiac reactivity to pain of blood collection. Among infants born ≤28 weeks gestational age (GA), but not 29–32 weeks GA, higher cumulative neonatal procedural pain exposure was related to lower cortisol response to stress and to lower facial (but not autonomic) reactivity to pain, at 32 weeks PCA, independent of early illness severity and morphine exposure since birth. Repeated neonatal procedural pain exposure among neurodevelopmentally immature preterm infants was associated with down-regulation of the hypothalamic–pituitary–adrenal axis, which was not counteracted with morphine. Differential effects of early pain on development of behavioral, physiologic and hormonal systems warrant further investigation.

Stress reactivity in 15-month-old infants: links with infant temperament, cognitive competence, and attachment security.

In a sample of eighty-five 15-month-old infants, salivary cortisol was obtained prior to and following a potentially stressful episode in which the child was confronted with a stranger and with a frightening robot. Infant characteristics such as anger proneness, cognitive competence, and attachment security were expected to be related to cortisol reactivity during the stressful event. The results showed higher cortisol reactivity in more anger-prone infants and in infants with higher levels of cognitive development as assessed with the Bayley Scales of Infant Development (N. Bayley, 1969). Attachment security, assessed with the Attachment Q-Set (AQS; E. Waters, 1995), was found to moderate the relation between cognitive level and cortisol reactivity; the positive relation between cognitive development and cortisol response was found in only infants with low AQS security scores. The findings may have important implications for research in the development of self-regulation in humans as well as in studies with animals.