A longitudinal study on the association between trait mindfulness and maternal bonding across the perinatal period.

AIMS/BACKGROUND: The mother-to-infant is important for healthy child development. The current study focused on the association between maternal trait mindfulness and the course of maternal bonding from pregnancy to one year postpartum. DESIGN/METHODS: Women participating in a prospective perinatal cohort study (n = 1003) completed online questionnaires on maternal bonding (Pre- and Post-natal Bonding Scale) at 28 weeks of pregnancy, and at 8 weeks, 6 months and 12 months postpartum. At 20 weeks of pregnancy, women completed the Three Facet Mindfulness Questionnaire - Short Form. Multilevel analyses were used to analyse 1) changes in maternal bonding over time and 2) the relationship of these changes with different facets of trait mindfulness measured once during pregnancy. Demographics, obstetrics, and depressive symptoms were controlled for. RESULTS: Results showed that maternal bonding first increased from pregnancy to 8 weeks postpartum and then remained relatively stable throughout the first-year postpartum. On average, women with high scores on acting with awareness and non-judging also scored higher on maternal bonding, but demonstrated a smaller increase in maternal bonding scores over time when compared to women with medium and low scores on these mindfulness facets. Furthermore, non-reacting was also positively associated with the level of maternal bonding but was not related to the course of bonding over time. The main effects of non-reacting and non-judging were not significant after adjusting for covariates. Depressive symptoms and a high educational level were negatively associated with bonding. CONCLUSION: Mindfulness-based interventions may be helpful in supporting expectant mothers who are at risk for suboptimal bonding.

Paternal bonding in pregnancy and early parenthood: a qualitative study in first-time fathers.

The birth of an infant marks a period of profound change in first-time parents. Parental love and warmth, however, already begin to develop during pregnancy. Also for fathers, the development of bonding to the infant may be a unique process. The current qualitative study aimed to explore views and experiences of first-time fathers on the origins and development of paternal bonding during pregnancy and early childhood. In total, 30 in-depth semi-structured interviews were conducted with expectant fathers (second or third trimester of pregnancy; n = 10) and fathers of infants (0-6 months postpartum; n = 11) and toddlers (2-3 years of age; n = 9). Two major themes were uncovered from the data: feelings of bonding and facilitators of bonding. The first theme was supported with three subthemes: 1) from abstract to concrete, 2) positive emotions, and 3) uncertainties and worries. The second theme, facilitators of bonding, was supported with four subthemes: 1) experiencing the foetus, 2) meeting the child, 3) interaction, and 4) communication. Similar to previous studies, our results suggested that, in most fathers, paternal bonding originates in pregnancy and that it evolves over time. Seeing or feeling the child, both during pregnancy and postpartum, as well as interacting or communicating with the child, appears to facilitate fathers' feelings of bonding. Involving fathers in pregnancy, childbirth, and parenting may be essential for their bonding process.

Parents of young infants report poor mental health and more insensitive parenting during the first Covid-19 lockdown.

BACKGROUND: The Covid-19 pandemic has put an unprecedented pressure on families with children. How parents were affected by the first Covid-19 lockdown during the early postpartum period, an already challenging period for many, is unknown. AIM: To investigate the associations between Covid-19 related stress, mental health, and insensitive parenting practices in mothers and fathers with young infants during the first Dutch Covid-19 lockdown. METHODS: The Dutch Covid-19 and Perinatal Experiences (COPE-NL) study included 681 parents of infants between 0 and 6 months (572 mothers and 109 fathers). Parents filled out online questionnaires about Covid-19 related stress, mental health (i.e. anxiety and depressive symptoms), and insensitive parenting. Hierarchical regression models were used to analyze the data. RESULTS: Parents of a young infant reported high rates of Covid-19 related stress, with higher reported stress in mothers compared to fathers. Additionally, the percentages of mothers and fathers experiencing clinically meaningful mental health symptoms during the pandemic were relatively high (mothers: 39.7% anxiety, 14.5% depression; fathers: 37.6% anxiety, 6.4% depression). More Covid-19 related stress was associated with more mental health symptoms in parents and increased insensitive parenting practices in mothers. CONCLUSIONS: The results emphasize the strain of the pandemic on young fathers' and mothers' mental health and its potential negative consequences for parenting. As poor parental mental health and insensitive parenting practices carry risk for worse child outcomes across the lifespan, the mental health burden of the Covid-19 pandemic might not only have affected the parents, but also the next generation.

The association of unplanned pregnancy with perinatal depression: a longitudinal cohort study.

Perinatal depression is common, affecting approximately 7-13% of women. Studies have shown an association between unplanned pregnancy and perinatal depressive symptoms, but many used a cross-sectional design and limited postnatal follow-up. The current study investigated the association of unplanned pregnancy with perinatal depressive symptoms using a longitudinal cohort study that followed women from the first trimester until 12 months postpartum. Pregnant women (N = 1928) provided demographic and clinical data and information about pregnancy intention at the first trimester. Depressive symptoms were assessed during each trimester of pregnancy and five times postpartum using the Edinburgh Postnatal Depression Scale (EPDS) until 12 months postpartum. Mixed model analyses were used to investigate the association between an unplanned pregnancy and the level of depressive symptoms. Women with an unplanned pregnancy (N = 111, 5.8%) reported persistently higher levels of depressive symptoms during the entire perinatal period compared to women with a planned pregnancy, after adjustment for confounders (p < 0.001). However, the course of depressive symptom scores over time in women with an unplanned pregnancy was similar to that of women with a planned pregnancy. Lower age (p = 0.006), unemployment (p = 0.004), and history of depression (p < 0.001) were significantly associated with higher levels of perinatal depressive symptoms. An unplanned pregnancy may have a long-lasting negative impact on a woman's perinatal mental health. Therefore, women with an unplanned pregnancy may benefit from systematic follow-up during the perinatal period with contingent mental health support.

In sync with your child: The potential of parent-child electroencephalography in developmental research.

Healthy interaction between parent and child is foundational for the child's socioemotional development. Recently, an innovative paradigm shift in electroencephalography (EEG) research has enabled the simultaneous measurement of neural activity in caregiver and child. This dual-EEG or hyperscanning approach, termed parent-child dual-EEG, combines the strength of both behavioral observations and EEG methods. In this review, we aim to inform on the potential of dual-EEG in parents and children (0-6 years) for developmental researchers. We first provide a general overview of the dual-EEG technique and continue by reviewing the first empirical work on the emerging field of parent-child dual-EEG, discussing the limited but fascinating findings on parent-child brain-to-behavior and brain-to-brain synchrony. We then continue by providing an overview of dual-EEG analysis techniques, including the technical challenges and solutions one may encounter. We finish by discussing the potential of parent-child dual-EEG for the future of developmental research. The analysis of multiple EEG data is technical and challenging, but when performed well, parent-child EEG may transform the way we understand how caregiver and child connect on a neurobiological level. Importantly, studying objective physiological measures of parent-child interactions could lead to the identification of novel brain-to-brain synchrony markers of interaction quality.

Improving the generalizability of infant psychological research: The ManyBabies model.

Yarkoni's analysis clearly articulates a number of concerns limiting the generalizability and explanatory power of psychological findings, many of which are compounded in infancy research. ManyBabies addresses these concerns via a radically collaborative, large-scale and open approach to research that is grounded in theory-building, committed to diversification, and focused on understanding sources of variation.

The COVID-19 outbreak increases maternal stress during pregnancy, but not the risk for postpartum depression.

The COVID-19 pandemic affects society and may especially have an impact on mental health of vulnerable groups, such as perinatal women. This prospective cohort study of 669 participating women in the Netherlands compared perinatal symptoms of depression and stress during and before the pandemic. After a pilot in 2018, recruitment started on 7 January 2019. Up until 1 March 2020 (before the pandemic), 401 women completed questionnaires during pregnancy, of whom 250 also completed postpartum assessment. During the pandemic, 268 women filled out at least one questionnaire during pregnancy and 59 postpartum (1 March-14 May 2020). Pregnancy-specific stress increased significantly in women during the pandemic. We found no increase in depressive symptoms during pregnancy nor an increase in incidence of high levels of postpartum depressive symptoms during the pandemic. Clinicians should be aware of the potential for increased stress in pregnant women during the pandemic.

Functional Connectome of the Fetal Brain.

Large-scale functional connectome formation and reorganization is apparent in the second trimester of pregnancy, making it a crucial and vulnerable time window in connectome development. Here we identified which architectural principles of functional connectome organization are initiated before birth, and contrast those with topological characteristics observed in the mature adult brain. A sample of 105 pregnant women participated in human fetal resting-state fMRI studies (fetal gestational age between 20 and 40 weeks). Connectome analysis was used to analyze weighted network characteristics of fetal macroscale brain wiring. We identified efficient network attributes, common functional modules, and high overlap between the fetal and adult brain network. Our results indicate that key features of the functional connectome are present in the second and third trimesters of pregnancy. Understanding the organizational principles of fetal connectome organization may bring opportunities to develop markers for early detection of alterations of brain function.SIGNIFICANCE STATEMENT The fetal to neonatal period is well known as a critical stage in brain development. Rapid neurodevelopmental processes establish key functional neural circuits of the human brain. Prenatal risk factors may interfere with early trajectories of connectome formation and thereby shape future health outcomes. Recent advances in MRI have made it possible to examine fetal brain functional connectivity. In this study, we evaluate the network topography of normative functional network development during connectome genesis in utero Understanding the developmental trajectory of brain connectivity provides a basis for understanding how the prenatal period shapes future brain function and disease dysfunction.

Impact of maternal childhood trauma on child behavioral problems: The role of child frontal alpha asymmetry.

Childhood trauma is associated with many long-term negative outcomes, and is not limited to the individual experiencing the trauma, but extends to subsequent generations. However, mechanisms underlying the association between maternal childhood trauma and child psychopathology are not well understood. Here, we targeted frontal alpha asymmetry (FAA) as a potential underlying factor of the relationship between maternal childhood trauma and child behavioral problems. Electroencephalography (EEG) was recorded from (N = 45) children (Mean age = 57.9 months, SD = 3.13) during an eyes-closed paradigm in order to evaluate FAA. Mothers reported on their childhood trauma experiences using the Childhood Trauma Questionnaire (CTQ), and on their child's behavior using the child behavior checklist (CBCL). We found that maternal childhood trauma significantly predicted child total, internalizing, and externalizing behavior at age 5 years. We also observed a role for FAA such that it acted as a moderator, but not mediator, for behavioral problems. We found that children with relative more right/less left frontal activity were more at risk to develop behavioral problems when their mother had been exposed to trauma in her childhood. These results indicate that child frontal asymmetry may serve as a susceptibility marker for child behavioral problems.

Children prenatally exposed to maternal anxiety devote more attentional resources to neutral pictures.

Maternal anxiety during pregnancy can negatively affect fetal neurodevelopment, predisposing the offspring to a higher risk of behavioral and emotional problems later in life. The current study investigates the association between maternal anxiety during pregnancy and child affective picture processing using event-related brain potentials (ERPs). Mothers reported anxiety during the second trimester using the anxiety subscale of the Symptom Checklist (SCL-90). At age 4 years, child affective picture processing (N = 86) was measured by recording ERPs during viewing of neutral, pleasant, and unpleasant pictures selected from the International Affective Pictures System. The late positive potential (LPP)-an ERP component reflecting individual differences in affective processing-was used as child outcome. The expected positive association between maternal anxiety and LPP amplitude for unpleasant pictures was not found. Nevertheless, we found a positive association between maternal anxiety during pregnancy and LPP amplitudes for neutral pictures in the middle and late time window at anterior locations (all p < .05). These associations remained significant after adjusting for maternal postnatal anxiety and gestational age at birth and after FDR correction for multiple comparisons. Our study provides neurophysiological evidence that children prenatally exposed to higher maternal anxiety devote more attentional resources to neutral pictures, but not to unpleasant pictures. Possibly, these children show enhanced vigilance for threat when viewing neutral pictures. Although useful in dangerous environments, this enhanced vigilance may predispose children prenatally exposed to higher maternal anxiety to developing behavioral and/or emotional problems later in life. A video abstract of this article can be viewed at: https://www.youtube.com/watch?v=kEzYi6IS2HA.

Prenatal neural origins of infant motor development: Associations between fetal brain and infant motor development.

Functional circuits of the human brain emerge and change dramatically over the second half of gestation. It is possible that variation in neural functional system connectivity in utero predicts individual differences in infant behavioral development, but this possibility has yet to be examined. The current study examines the association between fetal sensorimotor brain system functional connectivity and infant postnatal motor ability. Resting-state functional connectivity data was obtained in 96 healthy human fetuses during the second and third trimesters of pregnancy. Infant motor ability was measured 7 months after birth using the Bayley Scales of Infant Development. Increased connectivity between the emerging motor network and regions of the prefrontal cortex, temporal lobes, posterior cingulate, and supplementary motor regions was observed in infants that showed more mature motor functions. In addition, females demonstrated stronger fetal-brain to infant-behavior associations. These observations extend prior longitudinal research back into prenatal brain development and raise exciting new ideas about the advent of risk and the ontogeny of early sex differences.

Browsing throughout pregnancy: The longitudinal course of social media use during pregnancy.

BACKGROUND: The number of people using social media has substantially increased over the past years. Previous studies have shown associations between social media overuse and mental health problems during pregnancy. The current study evaluates changes in social media use during pregnancy. METHODS: Pregnant women were recruited at their first antenatal appointment between January 2020 and July 2022 (N = 1135). The time spent on social media, frequency of social media use and problematic social media use, using the Bergen Social Media Addiction Scale (BSMAS), were assessed at 12, 20 and 28 weeks of pregnancy. Pearson r correlations and repeated measures ANOVAs were performed to assess possible changes in social media use over the course of pregnancy. Lastly, we stratified social media use throughout pregnancy for parity. RESULTS: There was a significant change in social media use over time, for the time spent on social media, frequency of social media use and problematic social media use. Mean social media scores were the lowest at 12 weeks of pregnancy and increased significantly at 20 weeks of pregnancy, after which they remained stable at 28 weeks. Compared to multiparous women, primiparous women spent more time on social media at 20 weeks of pregnancy, but not at 12 or 28 weeks. CONCLUSION: Because overuse of social media has been associated with poor mental health, healthcare professionals should be aware of the intensity of social media use throughout pregnancy.

The association of maternal-infant interactive behavior, dyadic frontal alpha asymmetry, and maternal anxiety in a smartphone-adapted still face paradigm.

Mother-infant interactions form a strong basis for emotion regulation development in infants. These interactions can be affected by various factors, including maternal postnatal anxiety. Electroencephalography (EEG) hyperscanning allows for simultaneous assessment of mother-infant brain-to-behavior association during stressful events, such as the still-face paradigm (SFP). This study aimed at investigating dyadic interactive behavior and brain-to-behavior association across SFP and identifying neural correlates of mother-infant interactions in the context of maternal postnatal anxiety. We measured frontal alpha asymmetry (FAA), a physiological correlate of emotion regulation and a potential marker of risk for psychopathology. To emulate real-life interactions, EEG and behavioral data were collected from 38 mother-infant dyads during a smartphone-adapted dual-SFP. Although the behavioral data showed a clear still-face effect for the smartphone-adapted SFP, this was not reflected in the infant or maternal FAA. Brain-to-behavior data showed higher infant negative affect being associated with more infant leftward FAA during the still-face episodes. Finally, mothers with higher postnatal anxiety showed more right FAA during the first still-face episode, suggesting negative affectivity and a need to withdraw from the situation. Our results form a baseline for further research assessing the effects of maternal postnatal anxiety on infants' FAA and dyadic interactive behavior.

Trait mindfulness during pregnancy and maternal-infant bonding: Longitudinal associations with infant temperament and social-emotional development.

Maternal love and caregiving are pillars for optimal child development and may affect infant outcomes from pregnancy onwards. The present study aimed to examine whether maternal trait mindfulness during pregnancy and pre- and postnatal maternal-infant bonding were associated with maternal perceptions of infant temperament and social-emotional development. In total, 408 Dutch women (Mage = 31.33, SD = 3.59) participated in a prospective perinatal cohort study and completed questionnaires on trait mindfulness, prenatal bonding, postnatal bonding, infant temperament, and infant social-emotional development at 20 and 28 weeks of gestation, and 10 weeks, 6 and 12 months postpartum, respectively. Path analyses demonstrated that higher levels of the trait mindfulness facet non-judging (i.e., refraining from judgments about own feelings and thoughts) were associated with more pre- and postnatal maternal bonding and fewer social-emotional problems as perceived by the mother. Adopting an accepting and non-judgmental attitude may promote positive feelings of bonding and benefit the infant in terms of having fewer social-emotional problems in the first year of life. Mindfulness interventions may be offered to pregnant women in order to enhance maternal bonding and improve infant outcomes after birth.

Breastfeeding and room-sharing during COVID-19 in the Netherlands: The impact of perinatal healthcare support.

AIM: The recommendations of 6 months of exclusive breastfeeding (EBF) and parent-infant room-sharing (RS) are often not followed. As these early caregiving practices may have been affected by the COVID-19-related restrictions, we documented BF and RS practices in the Netherlands (2020-2021) and the effects of perceived perinatal healthcare support. METHODS: Pregnant women and mothers of an infant younger than 6 months (N = 784) completed online questionnaires (e.g., demographic information, the impact of COVID-19 on their lives aspects, infant childcare practices) twice: at the beginning of the pandemic and when the infant reached 6 months of age. RESULTS: The pandemic EBF practices mirrored pre-pandemic Dutch reports (17.8 %; Mduration = 3.4 months), while RS rates and duration seemingly doubled (30.6 %; Mduration = 3.98 months). Higher maternal education (r = 0.18) and multiparity (r = 0.08) were significantly associated with longer EBF, and similarly for education (r = 0.17) and multiparity (r = 0.11) with RS durations. Higher perceived perinatal healthcare support predicted shorter RS duration [ß = -0.509, t(5,596) = -2.27, p = .023]. CONCLUSION: While the COVID-19 pandemic did not impact EBF, it may have promoted RS. The negative association between perinatal healthcare support and RS may suggest that parents who need more support from their providers also experience more challenges adhering to RS recommendations, yet this hypothesis remains to be corroborated.

Maternal anxiety during pregnancy is associated with weaker prefrontal functional connectivity in adult offspring.

BACKGROUND: The connectome, constituting a unique fingerprint of a person's brain, may be influenced by its prenatal environment, potentially affecting later-life resilience and mental health. METHODS: We conducted a prospective resting-state functional Magnetic Resonance Imaging study in 28-year-old offspring (N = 49) of mothers whose anxiety was monitored during pregnancy. Two offspring anxiety subgroups were defined: "High anxiety" (n = 13) group versus "low-to-medium anxiety" (n = 36) group, based on maternal self-reported state anxiety at 12-22 weeks of gestation. To predict resting-state functional connectivity of 32 by 32 ROIs, maternal state anxiety during pregnancy was included as a predictor in general linear models for both ROI-to-ROI and graph theoretical metrics. Sex, birth weight and postnatal anxiety were included as covariates. RESULTS: Higher maternal anxiety was associated with weaker functional connectivity of medial prefrontal cortex with left inferior frontal gyrus (t = 3.45, pFDR < 0.05). Moreover, network-based statistics (NBS) confirmed our finding and revealed an additional association of weaker connectivity between left lateral prefontal cortex with left somatosensory motor gyrus in the offspring. While our results showed a general pattern of lower functional connectivity in adults prenatally exposed to maternal anxiety, we did not observe significant differences in global brain networks between groups. CONCLUSIONS: Weaker (medial) prefrontal cortex functional connectivity in the high anxiety adult offspring group suggests a long-term negative impact of prenatal exposure to high maternal anxiety, extending into adulthood. To prevent mental health problems at population level, universal primary prevention strategies should aim at lowering maternal anxiety during pregnancy.

Intergenerational Transmission of Maternal Childhood Maltreatment Prior to Birth: Effects on Human Fetal Amygdala Functional Connectivity.

OBJECTIVE: Childhood maltreatment (CM) is a potent risk factor for developing psychopathology later in life. Accumulating research suggests that the influence is not limited to the exposed individual but may also be transmitted across generations. In this study, we examine the effect of CM in pregnant women on fetal amygdala-cortical function, prior to postnatal influences. METHOD: Healthy pregnant women (N = 89) completed fetal resting-state functional magnetic resonance imaging (rsfMRI) scans between the late second trimester and birth. Women were primarily from low socioeconomic status households with relatively high CM. Mothers completed questionnaires prospectively evaluating prenatal psychosocial health and retrospectively evaluating trauma from their own childhood. Voxelwise functional connectivity was calculated from bilateral amygdala masks. RESULTS: Connectivity of the amygdala network was relatively higher to left frontal areas (prefrontal cortex and premotor) and relatively lower to right premotor area and brainstem areas in fetuses of mothers exposed to higher CM. These associations persisted after controlling for maternal socioeconomic status, maternal prenatal distress, measures of fetal motion, and gestational age at the time of scan and at birth. CONCLUSION: Pregnant women's experiences of CM are associated with offspring brain development in utero. The strongest effects were found in the left hemisphere, potentially indicating lateralization of the effects of maternal CM on the fetal brain. This study suggests that the time frame of the Developmental Origins of Health and Disease research should be extended to exposures from mothers' childhood, and indicates that the intergenerational transmission of trauma may occur prior to birth.

Social media use as a risk factor for depressive symptoms during pregnancy.

BACKGROUND: Accumulating research has shown associations between excessive social media use (SMU) with depressive symptoms. Depression is common during pregnancy, but it is not known whether SMU plays a role in the etiology and clinical course of depressive symptoms during pregnancy. METHODS: The current study is a prospective cohort study with Dutch-speaking pregnant women recruited at the first antenatal appointment (N = 697). Depressive symptoms were measured at each trimester of pregnancy using the Edinburgh Depression Scale. Growth mixture modeling was used to determine classes of women based on longitudinal trajectories of depressive symptoms. SMU was assessed at 12 weeks of pregnancy, specifically, intensity (time and frequency) and problematic SMU (Bergen Social Media Addiction Scale). Multinomial logistic regression analyses were used to examine the associations between SMU and trajectories of depressive symptoms. RESULTS: Three trajectories of depressive symptoms during pregnancy were identified: a low stable (N = 489, 70.2 %), intermediate stable (N = 183, 26.3 %), and high stable (N = 25, 3.6 %) class. SMU Time and Frequency were significantly associated with belonging to the high stable class. Problematic SMU was significantly associated with belonging to the intermediate or high stable class. LIMITATIONS: The study does not allow to draw conclusions about causality. The group sizes of the three trajectories differed considerably. Data were collected during the COVID-19 pandemic which may have influenced the results. SMU was measured by self-report. CONCLUSIONS: These results indicate that both higher intensity of SMU (time and frequency) and problematic SMU may be a risk factor for higher levels of prenatal depressive symptoms during pregnancy.

Brains in Sync: Practical Guideline for Parent-Infant EEG During Natural Interaction.

Parent-infant EEG is a novel hyperscanning paradigm to measure social interaction simultaneously in the brains of parents and infants. The number of studies using parent-infant dual-EEG as a theoretical framework to measure brain-to-brain synchrony during interaction is rapidly growing, while the methodology for measuring synchrony is not yet uniform. While adult dual-EEG methodology is quickly improving, open databases, tutorials, and methodological validations for dual-EEG with infants are largely missing. In this practical guide, we provide a step-by-step manual on how to implement and run parent-infant EEG paradigms in a neurodevelopmental laboratory in naturalistic settings (e.g., free interactions). Next, we highlight insights on the variety of choices that can be made during (pre)processing dual-EEG data, including recommendations on interpersonal neural coupling metrics and interpretations of the results. Moreover, we provide an exemplar dataset of two mother-infant dyads during free interactions ("free play") that may serve as practice material. Instead of providing a critical note, we would like to move the field of parent-infant EEG forward and be transparent about the challenges that come along with the exciting opportunity to study the development of our social brain within the naturalistic context of dual-EEG.

Prenatal hair cortisol concentrations during the COVID-19 outbreak: Associations with maternal psychological stress and infant temperament.

BACKGROUND: Maternal psychological stress during pregnancy, including stress resulting from disasters and trauma, has been linked to temperamental difficulties in offspring. Although heightened cortisol concentrations are often hypothesized as an underlying mechanism, evidence supporting this mechanism is not consistent, potentially because of methodological issues and low stress in the population. AIM: To address these issues, this preregistered study investigated the following associations between: 1) prenatal psychological stress and hair cortisol, as a biomarker for chronic stress, during the COVID-19 outbreak (i.e., as a major worldwide psychological stressor), and 2) maternal hair cortisol during the COVID-19 outbreak and later infant temperamental negative affectivity and orienting/regulation. Additionally, we explored whether associations were different for women with low versus high socioeconomic status (SES; maternal education and annual household income) and at different stages of pregnancy. METHOD: Pregnant women (N = 100) filled out online questionnaires during the first COVID-19 lockdown. Six months later, when most mothers were still pregnant or had just given birth, maternal hair samples were collected during home visits. When infants were six months old, mothers reported on their infant's temperament. RESULTS: Although hierarchical regression analyses revealed no associations between prenatal COVID-19 psychological stress and hair cortisol during the COVID-19 outbreak, SES proved to be a moderator in this association. Only pregnant women with higher levels of SES, not lower levels, showed a positive association between work-related and social support-related COVID-19 worries and hair cortisol. Finally, prenatal hair cortisol was not associated with later infant temperamental negative affectivity and orienting/regulation. CONCLUSION: Although the COVID-19 outbreak proved to be a major psychological stressor worldwide, the physiological impact of the crisis might be different for pregnant women with higher SES as compared to lower SES.