Researchers have begun to examine the psychological toll of the ongoing global COVID-19 pandemic. Data are now emerging indicating that there may be long-term adverse effects of the pandemic on new mothers and on children born during this period. In a longitudinal study of maternal mental health and child emotional development during the pandemic, we conducted online assessments of a cohort of women at two time points: when they were pregnant at the beginning of the surge of the pandemic in the United States (baseline, N = 725), and approximately 1 year postpartum (follow-up, N = 296), examining prenatal and postnatal maternal mental health, prenatal pandemic-related stress, and infant temperament. Pandemic-related stress at baseline was associated with concurrent depressive symptoms and infant negative affect at follow-up. Baseline maternal depressive symptoms were associated with follow-up depressive symptoms, which in turn were also associated with infant negative affect. Pandemic-related stress during pregnancy may have enduring effects on infant temperament. These findings have important implications for our understanding of the emotional development of children who were in utero during the COVID-19 pandemic.

High levels of early emotionality (of either negative or positive valence) are hypothesized to be important precursors to early psychopathology, with attention-deficit/hyperactivity disorder (ADHD) a prime early target. The positive and negative affect domains are prime examples of Research Domain Criteria (RDoC) concepts that may enrich a multilevel mechanistic map of psychopathology risk. Utilizing both variable-centered and person-centered approaches, the current study examined whether levels and trajectories of infant negative and positive emotionality, considered either in isolation or together, predicted children's ADHD symptoms at 4 to 8 years of age. In variable-centered analyses, higher levels of infant negative affect (at as early as 3 months of age) were associated with childhood ADHD symptoms. Findings for positive affect failed to reach statistical threshold. Results from person-centered trajectory analyses suggest that additional information is gained by simultaneously considering the trajectories of positive and negative emotionality. Specifically, only when exhibiting moderate, stable or low levels of positive affect did negative affect and its trajectory relate to child ADHD symptoms. These findings add to a growing literature that suggests that infant negative emotionality is a promising early life marker of future ADHD risk and suggest secondarily that moderation by positive affectivity warrants more consideration.

Individual differences in temperament have been well-described, but individual differences in temperament trajectories require elaboration. Specifically, it is unknown if subgroups of infants display different developmental patterns and if these patterns relate to later behavioral problems. The aims were to identify distinct developmental patterns in broad dimensions of temperament among typically developing infants, to determine whether these developmental patterns differ by sex, to evaluate how developmental patterns within each dimension of temperament relate to developmental patterns within other dimensions of temperament, and to determine whether developmental patterns of infant temperament are associated with internalizing and externalizing behavior at 2 years of age. Data from the longitudinal Alberta Pregnancy Outcomes and Nutrition study (n = 1,819) were used to model latent class trajectories of parent-reported infant temperament at 3, 6, and 12 months. Four to five unique latent trajectories were identified within each temperament dimension. Sex was not associated with trajectory groups. Developmental coordination was observed between trajectories of negative emotionality and regulatory capacity, and between regulatory capacity and positive affect, but not between positive affect and negative emotionality. Negative emotionality and regulatory capacity predicted internalizing and externalizing behavior. Patterns of development in infant temperament, and not just intensity of temperament, contribute toward later problem behavior.

Maternal pre-pregnancy weight has been related with young singletons’ cognitive and behavioral development, but it is not clear if it has an effect on temperament. We used a twin cohort to evaluate the association between maternal pre-pregnancy body mass index (BMI) and infants’ temperament. The mothers of 834 twins answered questions regarding their pre-pregnancy BMI and their 0- to 18-month-old children’s temperament using the Revised Infant Behavior Questionnaire. Three temperamental dimensions were examined: activity level, distress to limitation and duration of orienting. The relationship between maternal pre-pregnancy BMI and each temperamental component was investigated by means of multilevel mixed-effects linear regression analysis. We found no clear evidence of an association of maternal pre-pregnancy BMI with twins’ temperament. The development of temperament is influenced by a large number of factors, probably different from those influencing children’s emotional and behavioral development.

A mother’s emotional state is a well-known environmental factor that relates to the development of infant temperament. However, some relevant issues have not yet been fully explored. The current study examines the influence of determined maternal, contextual and perinatal variables on infant temperament and the mother’s confidence in caregiving during the first weeks of life. A prospective study was carried out in three-hundred and seventeen newborns and their mothers. Perinatal and socio-demographic variables were recorded. The mother’s anxiety and mood were measured in the first days after childbirth and again at 8 weeks. Infant temperament and the mother’s confidence in caregiving were measured at 8 weeks. A mother’s postpartum anxiety following delivery was the best predictor for most of the variables of infant temperament, including infant irritability (p = .001), and other child variables like infant sleep (p = .0003) and nursing difficulty (p = .001). Contextual-family variables, such as the number of people at home (p = .0024) and whether they were primiparous (p = .001), were the best predictors for a mother´s confidence in caregiving. Support was found for an early effect of maternal anxiety on infant temperament. The results have clinical implications for postnatal psychological interventions.

This study examined the association between two common polymorphisms, the dopamine D4 receptor (DRD4) gene and the serotonin transporter promoter (5-HTTLPR) gene and temperament in 61 infants aged 12 months. Twenty-two infants had a least one copy of the 6–8 repeat DRD4 alleles (L-DRD4) and 39 had two copies of the 2–5 repeat allele (S-DRD4). Twenty infants were homozygous for the short form (s/s) of 5-HTTLPR while 41 were either heterozygous for the short and the long form (l/s) or were homozygous for the long form (l/l). The infants were observed in a series of standard temperament episodes that elicited fear, anger, pleasure, interest, and activity. L-DRD4 infants showed less interest in a structured block play situation and more activity in a free play situation. They also displayed less anger in an episode of mild physical restraint. Infants with s/s 5-HTTLPR showed less fearful distress to stranger approach and less pleasure in a structured play situation than infants with l/l or l/s 5-HTTLPR. Duration of looking during block play was affected by a significant interaction between DRD4 and 5-HTTLPR. Shortest duration of looking was associated with the L-DRD4 and s/s 5-HTTLPR genotypes. The implications and limitations of these findings are discussed.

In the Louisville Twin Study, laboratory observations of twin infants' temperament at 12, 18, and 24 months were linked with parental ratings from temperament questionnaires. Core dimensions of temperament were extracted by factor analysis applied to each set of measures at each age. The laboratory temperament dimension was recurrently represented by emotional tone, social orientation, attentiveness, and reaction to restraint. The questionnaire temperament dimension was recurrently represented by mood, approach/withdrawal and adaptability. The laboratory and questionnaire dimensions were found to be correlated at each age (convergent correlations: 0.38 to 0.52) and to be stable across ages (stability correlations 0.37 to 0.66). The temperament dimensions were used to demonstrate that temperament profiles were more concordant for identical than for fraternal twin pairs. The results demonstrate the genetic influences on (a) the primary dimensions of temperament and (b) the developmental transformations of temperament.