Prenatal maternal anxiety or stress and cognitive functioning

I find prenatal research intriguing and have written before about research on its effects. Delagneau, Twilhaar, Testa, van Veen & Anderson (2022) published “Association Between Prenatal Maternal Anxiety and/or Stress and Offspring's Cognitive Functioning: A meta-analysis” in Child Development.

This meta-analysis examined the relationship between prenatal maternal stress and/or anxiety and the outcomes of children aged 3 months to 9 years. Of the 8754 studies published before June 2021 that were synthesized, 17 conducted in Western countries were included in the meta-analysis (Ntotal = 23,307; Mmales 54%; Methnicity White 77%, Pacific 15%, African American/Black 10%, Middle Eastern 7%, Eastern 8%). Effect sizes ranged from −0.41 to 0.15. A weak negative association was found between prenatal stress and/or anxiety exposure and children's general intellectual development. Associations varied based on the type of exposure. 

Many women worldwide experience some levels of stress during pregnancy. Studies report that the prevalence of maternal stress during pregnancy typically ranges from 5.5% to 78% and increased considerably during the COVID-19 pandemic. There is now reliable evidence that maternal prenatal stress is associated with negative health and neurobehavioral outcomes in the offspring, such as delayed cognitive development in infants and toddlers. Whether these associations extend to older children and specific cognitive domains (e.g., attention and memory), however, remains uncertain. Furthermore, our understanding of the relationship between maternal prenatal stress and children's cognitive development is hampered by the lack of consistency in the way stress is defined and measured across studies and differences in the way children's cognitive outcomes are examined. Therefore, a quantitative review is needed on the association between prenatal stress and children's cognitive development which (1) separates the concepts of prenatal stress, (2) examines a range of cognitive outcomes beyond early childhood, and (3) separates different types of cognitive assessment.

Stress has previously been defined and measured as exposure to stressors, perceived stress, or stress response. Exposure to stressors refers to the presence of stimuli, such as life events, environmental factors, and daily hassles, which cause emotional difficulty. Perceived stress is an emotional reaction characterized by feelings or thoughts that arise from individuals' appraisal of life stressors and vary based on several factors, including one's social support, personality traits, and coping behaviors. A stress response is most commonly characterized as biological changes, including changes in cortisol levels, reduced uteroplacental blood flow in pregnant women, increased activation of the sympathetic nervous system, decreased activation of the parasympathetic nervous system, and increased secretion of catecholamines. It is triggered by an event that is perceived to be stressful and mediated by factors such as personality traits and cognitive appraisal processes. Interestingly, past studies have found a reduced physiological stress response in pregnant women, including lower cardiovascular stress reactivity and catecholamine response, which may protect the developing fetus from exposure to low levels of stress during pregnancy. Nonetheless, physiological stress responses in pregnant women remain present, highlighting the need to further explore these mechanisms and their impact on the developing fetus.

Stress is often recognized as a vulnerability factor for depression, however, depression has distinct clinical symptoms and pathophysiology and has been differentiated from stress in past studies. For these reasons, as well as a recent meta-analysis demonstrating an association between prenatal depressive symptoms and child development, we have not focused on maternal depression in this review.

Anxiety is a multi-dimensional construct, comprising state, and trait anxiety. State anxiety refers to situation-specific and transient negative emotion characterized by psychological and physiological reactions, such as irritability, difficulties concentrating, palpitations, and a reduction in serotonin release. Trait anxiety refers to an enduring characteristic of a person which predisposes them to experience more intense degrees of fear and worry across many situations that most people would not find threatening. Pregnancy-related anxiety has also been described, which refers to worries specifically related to pregnancy, such as giving birth or bearing a handicapped child.

Studies have shown that different aspects of stress and types of anxiety have independent associations with health and birth outcomes. As such, exposure to these different constructs may have a differential impact on the cognitive development of the child. Supporting this premise, meta-analytic findings of Tarabulsy et al. (2014) provide preliminary evidence that the strength of association between maternal prenatal stress and infants' cognitive development varies based on the type of stress examined. Specifically, they found a weak but significant inverse association between maternal prenatal stress or anxiety and early child cognitive development (r = −.05), but the relationship between life-events and cognitive development (r = −.31) was significantly greater than that for pregnancy-related anxiety (r = −.08) or other subjective assessments of stress or anxiety unrelated to pregnancy (r = −.02). However, the outcome of interest in this meta-analysis was restricted to the general intellectual skills of children aged 0 to 5, and did not examine the separate effects of perceived stress, stress response, trait anxiety, or state anxiety. Moreover, the number of studies examining the association between prenatal stress and children's cognitive development is growing rapidly and numerous relevant studies have been published since this meta-analysis.

The present review aimed to examine the relationship between prenatal maternal stress and anxiety and a range of key cognitive domains (i.e., general intellectual skills, attention, language, learning, memory, executive functions) in infancy, childhood, and adolescence (birth until 18 years of age). We also sought to examine the individual influence of the different aspects of stress and anxiety and type of cognitive measure used. 

This meta-analysis builds on previous findings and offers four unique contributions by focusing on (i) distinct types of stress and anxiety, (ii) specific cognitive domains, (iii) both infants and children aged up to 18 years old, and (iv) different types of cognitive measurements.

Two key findings emerged from this study. First, there was a weak negative association between the exposure to stress and anxiety (combined) during pregnancy and the offspring's general intellectual development. These findings are in line with those of previous systematic reviews and meta-analyses which reported a weak negative association between maternal prenatal stress and/or anxiety and infants' general intellectual skills. Our findings further suggest that meaningful associations did not extend to other cognitive skills, such as language, attention, and executive functions. 

The second key finding of this meta-analysis was that most studies which examined different types of prenatal maternal stress and/or anxiety exposure reported differential effects on children's cognitive skills. While our meta-analysis also showed a negative effect of anxiety but not general stress on executive functions and a negative effect of general stress but not anxiety on children's general intellectual skills, these differences could not be quantified due to a lack of studies. 

Preliminary findings showed that the influence of maternal prenatal stress and/or anxiety on children's cognitive function did not vary based on children's developmental stage or sex. Decades of research have demonstrated that the timing of prenatal stress and/or anxiety was important to take into account when examining child outcomes. Our findings suggest that children exposed to stress and/or anxiety early during pregnancy exhibit worse cognitive outcomes than those exposed to these emotional reactions states late in pregnancy. More research, however, is needed to ascertain this assumption, which is only based on five studies.

In summary, our findings support the current consensus that prenatal maternal stress and/or anxiety is likely to be negatively, albeit weakly, associated with offspring cognitive function. These findings are of public health significance and support the need for screening and interventions to prevent or minimize mental health problems in pregnant women and optimize child development. In particular, our findings highlight the need to separate the concepts of stress and anxiety in future research and investigate the influence of timing of prenatal stress and/anxiety exposure on children's cognitive abilities. Finally, we argue that too little is known about the relationship between maternal prenatal stress and/or anxiety and children's domains of cognitive function, in particular in children older than 2 years old. It is evident that more studies are called to better understand this relationship and, in turn, optimize child cognitive development in a context where prenatal maternal stress and anxiety are commonplace.

This is another long post, but potentially helpful in directing questions to parents and caregivers about maternal experiences of stress and anxiety, especially early in prenatal development.