High pregnancy anxiety during mid-gestation is associated with decreased gray matter density in 6-9-year-old children

Prenatal Origins of Neurological Development

A rapidly accumulating literature indicates that the prenatal period must be taken into account if we are to understand development of the central nervous system (CNS) across the life span. Evidence now suggests that intrauterine signals influence brain structure and affect cognitive function and emotional and physiological stress regulation in the offspring. Furthermore, prenatal hormone exposures are critical for priming the maternal brain for the challenges of motherhood and have implications for the mother’s brain structure and function that may last the rest of her lifetime. Just as the reciprocal nature of the parent–child relationship must be understood during the postnatal period, in order to understand the persisting influences of the intrauterine environment on neurodevelopment, the effects of the prenatal environment on both fetus and mother, as well as their reciprocal influences, must be appreciated. This is critical because the same hormones that program fetal development are those that shape the maternal brain and because prenatal bidirectional signaling may provide an adaptive function for both mother and fetus.

Racial disparities in pediatric intensive care unit admissions

OBJECTIVES

Racial disparities in therapies and outcomes in adult and neonatal ICUs are well documented; however, little is known regarding racial disparities in pediatric intensive care unit (PICU). Our objective was to determine whether racial disparities exist in the admission of critically ill children to the PICU.

METHODS

We retrospectively analyzed admissions to a PICU in a tertiary care pediatric hospital. Summarized demographic data was analyzed from the county health department.

RESULTS

Of the 4676 admissions to the PICU between January 1, 1997 and December 31, 1999, 1030 children were <48 months of age, lived in Shelby County, TN, and were either African American (789, 76.6%) or non-Hispanic white (241, 23.4%). The surrounding county was comprised of approximately 58% African American and 41% non-Hispanic white children ≤ 48 months of age. A history of premature birth was more common in African American children than non-Hispanic white children (46.8% vs. 32.8%; P < 0.0001). Mortality was 5.7% overall and was not significantly different between African Americans and non-Hispanic whites but was higher for those children with a history of premature birth (4.6% vs. 7.1%, P < 0.026). The overall relative risk of admission to the PICU for African American children was 2.12 (95% CI, 1.66-2.74), for African American children with a history of premature birth was 1.44 (95% CI, 0.96-2.21), and for full-term African American children was 1.82 (95% CI, 1.33 -2.49).

CONCLUSIONS

Racial differences in admission to the PICU exist with African American children having a greater risk for PICU admission than non-Hispanic white children.

An Overview of Psychological and Neurobiological Mechanisms by which Early Negative Experiences Increase Risk of Mood Disorders

OBJECTIVE

Early life experiences are associated with severe and long-lasting effects on behavioural and emotional functioning, which in turn are thought to increase the risk for unipolar depression and other disorders of affect regulation. The neurobiological and psychological mechanisms through which adverse early life experiences confer risk are poorly understood.

METHOD

Alterations in brain structure and function in limbic and prefrontal cortical regions have been linked to early negative experiences and to mood disorders.

RESULTS

There are a number of psychological domains that may be dysfunctional in people with mood disorders, and which, if the dysfunction occurs prior to onset of mood symptoms, may signify a risk factor for depression. Cognitive dysfunction has been examined in patients with mood disorders, with some suggestion that changes in cognitive function may antedate the onset of mood symptoms, and may be exacerbated in those who experienced early negative trauma. Social cognition, including emotion comprehension, theory of mind and empathy, represent under-studied domains of psychological function that may be negatively influenced by early adverse experience. Temperament and personality factors may also leave people vulnerable to mood instability.

CONCLUSION

This review summarizes the evidence for dysfunction in each of these domains for people with mood disorders.

Stress, glucocorticoids and liquorice in human pregnancy: programmers of the offspring brain

A suboptimal prenatal environment may induce permanent changes in cells, organs and physiology that alter social, emotional and cognitive functioning, and increase the risk of cardiometabolic and mental disorders in subsequent life ("developmental programming"). Although animal studies have provided a wealth of data on programming and its mechanisms, including on the role of stress and its glucocorticoid mediators, empirical evidence of these mechanisms in humans is still scanty. We review the existing human evidence on the effects of prenatal maternal stress, anxiety and depression, glucocorticoids and intake of liquorice (which inhibits the placental barrier to maternal glucocorticoids) on offspring developmental outcomes including, for instance, alterations in psychophysiological and neurocognitive functioning and mental health. This work lays the foundations for biomarker discovery and affords opportunities for prevention and interventions to ameliorate adverse outcomes in humans.

Sex-dependent changes induced by prenatal stress in cortical and hippocampal morphology and behaviour in rats: an update

Recent prospective studies have shown that gestational stress in humans is more likely to cause cognitive and emotional problems in the offspring if it occurs during weeks 12-20 of pregnancy. There are also suggestions that such problems may be gender dependent. This review describes recent studies that found sex differences in the behaviour and brain morphology of rats stressed prenatally during the equivalent period of neuronal development in humans. Learning deficits are more prevalent in males and anxious behaviour in females but their appearance depends also on the timing and intensity of the stress and the age when the offspring were tested. Cognitive deficits and anxiety are linked to a sex-dependent reduction in neurogenesis and in measures of dendritic morphology in the prefrontal cortex and hippocampal formation. Maternal adrenalectomy prior to the stress prevents the anxiety in both sexes and learning deficits in males. Corticosterone administration to the dam to mimic levels induced by stress reinstates only the anxiety, indicating that it arises from foetal exposure to corticosterone from the maternal circulation. Learning deficits in males may result from a combination of a reduction in testosterone and in aromatase activity, together with the action of other adrenal hormones.

Prenatal maternal anxiety and early childhood temperament

The consequences of exposure to prenatal maternal anxiety for the development of child temperament were examined in a sample of 120 healthy, 2-year-old children. Prenatal maternal state and pregnancy-specific anxiety (PSA) were measured five times during pregnancy, and maternal state anxiety was measured again at 2 years post partum. Child temperament was measured at 2 years using the Early Childhood Behavior Questionnaire. The relationship between the trajectory of maternal anxiety across gestation and negative affectivity was evaluated using hierarchical linear growth curve modeling. Higher maternal PSA between 13 and 17 weeks of gestation was associated with increased negative temperament in the children. This association could not be explained by postnatal maternal anxiety, demographic, or obstetric factors. Prenatal maternal state anxiety was not associated with child temperament. These findings demonstrate that PSA early in gestation has a distinctive influence on the developing fetus.

Maternal pregnancy-specific anxiety is associated with child executive function at 6-9 years age

Because fetal brain development proceeds at an extremely rapid pace, early life experiences have the potential to alter the trajectory of neurodevelopment, which may increase susceptibility for developmental and neuropsychiatric disorders. There is evidence that prenatal maternal stress and anxiety, especially worries specifically related to being pregnant, influence neurodevelopmental outcomes. In the current prospective longitudinal study, we included 89 women for whom serial data were available for pregnancy-specific anxiety, state anxiety, and depression at 15, 19, 25, 31, and 37 weeks gestation. When the offspring from the target pregnancy were between 6 and 9 years of age, their executive function was assessed. High levels of mean maternal pregnancy-specific anxiety over the course of gestation were associated with lower inhibitory control in girls only and lower visuospatial working memory performance in boys and girls. Higher-state anxiety and depression also were associated with lower visuospatial working memory performance. However, neither state anxiety nor depression explained any additional variance after accounting for pregnancy-specific anxiety. The findings contribute to the literature supporting an association between pregnancy-specific anxiety and cognitive development and extend our knowledge about the persistence of this effect until middle childhood.

Patterns of fetal heart rate response at ∼30 weeks gestation predict size at birth

There is evidence that fetal exposure to maternal stress is associated with adverse birth outcomes. Less is known about the association between fetal responses to a stressor and indicators of fetal maturity and developmental outcomes. The purpose of the present study was to determine whether fetal heart rate (FHR) patterns in response to a startling stimulus at ∼30 weeks of gestation were associated with gestational age at birth and birth weight. FHR was measured in 156 maternal-fetal dyads following a vibroacoustic stimulus. All pregnancies were singleton intrauterine pregnancies in English-speaking women who were primarily married, middle class, White and at least 18 years of age. Group-based trajectory modeling identified five groups of fetuses displaying distinctive longitudinal trajectories of FHR response to the startling stimulus. The FHR group trajectories were significantly associated with birth weight percentile (P < 0.01) even after controlling for estimated fetal weight at the time of assessment and parity, which are the known factors influencing birth weight (P < 0.01). Post hoc analyses indicated that two groups accounted for the association between FHR patterns and birth weight. The group (n = 23) with the lowest birth weight exhibited an immediate FHR deceleration followed by an immediate acceleration that does not recover. An FHR pattern characterized by immediate and fast acceleration to the peak and a slow discovery to baseline was associated with the highest birth weight. This is the first direct evidence showing that low birth weight and the resulting neurological consequences may have their origins in early fetal development.

The contribution of prenatal and postnatal maternal anxiety and depression to child maladjustment

BACKGROUND

The adverse effect of both pre- and post-natal maternal anxiety and depression on the development of offspring is shown by a large body of research. No published studies, however, have simultaneously: (i) controlled for co-occurring prenatal risks that may influence maternal prenatal anxiety and depression; (ii) compared the relative contributions of prenatal and postnatal maternal anxiety and depression on child functioning; and (iii) assessed a full range of child psychopathology and functioning to determine the relative effects of prenatal and postnatal anxiety and depression in the mother.

METHOD

Using 3,298 mother-offspring pairs, the authors examined these factors in a single-path analytic model. Measurements of maternal anxiety and depression were collected at two time points: 32 weeks prenatal and 1.5 years postnatal. Other prenatal risks were assessed between 8 and 32 weeks of gestation. Child outcomes included (a) ordered-categorical measures of DSM-IV externalizing and internalizing disorders, and (b) an assessment of verbal IQ.

RESULTS

In both the prenatal and postnatal periods, maternal depression had a wider impact on different types of child maladjustment than maternal anxiety, which appeared more specific to internalizing difficulties in the child. Of note, prenatal risks were prospectively associated with child externalizing difficulties and verbal IQ, beyond the effects of prenatal and postnatal maternal anxiety and depression.

CONCLUSION

The present results suggest that addressing both maternal anxiety and depression, in the prenatal and postnatal periods-as well as associated risk factors-may be the most effective approach to prevent adverse outcomes in the offspring.

Childhood trauma history differentiates amygdala response to sad faces within MDD

OBJECTIVE

Heightened amygdala reactivity to aversive stimuli in major depression is regarded as a core feature of the underlying physiology but individual differences in amygdala response may also arise secondary to persistent changes in limbic function during early neurodevelopment relative to stressors such as childhood trauma. We sought to determine whether heightened amygdala response is a core feature of depression or a general risk factor for psychopathology secondary to early life stress.

METHOD

Twenty unipolar depressed patients with and without a history of significant early life trauma and 16 healthy comparison subjects underwent functional MRI in a cross-sectional study comparing neural response to sad and neutral faces.

RESULTS

We observed a robust positive correlation between physical abuse and right amygdala response. A much weaker relationship with other forms of abuse and neglect was also found, suggesting differences between abuse subtypes and amygdala response. Group differences in amygdala response suggest heightened reactivity was not characteristic of persons with depression in general but was true primarily in those with a significant history of abuse.

CONCLUSION

These findings suggest the relationship between childhood trauma and risk for depression is mediated by heightened amygdala response but varies by abuse type. Preliminary evidence for two distinct depression phenotypes based on trauma history was also supported, consistent with differential etiology.

Brain enlargement and increased behavioral and cytokine reactivity in infant monkeys following acute prenatal endotoxemia

Infections and inflammatory conditions during pregnancy can dysregulate neural development and increase the risk for developing autism and schizophrenia. The following research utilized a nonhuman primate model to investigate the potential impact of a mild endotoxemia during pregnancy on brain maturation and behavioral reactivity as well as the infants' hormone and immune physiology. Nine pregnant female rhesus monkeys (Macaca mulatta) were administered nanogram concentrations of lipopolysaccharide (LPS) on two consecutive days, 6 weeks before term, and their offspring were compared to nine control animals. When tested under arousing challenge conditions, infants from the LPS pregnancies were more behaviorally disturbed, including a failure to show a normal attenuation of startle responses on tests of prepulse inhibition. Examination of their brains at 1 year of age with magnetic resonance imaging (MRI) revealed the unexpected finding of a significant 8.8% increase in global white matter volume distributed across many cortical regions compared to controls. More selective changes in regional gray matter volume and cortical thickness were noted in parietal, medial temporal, and frontal areas. While inhibited neural growth has been described previously after prenatal infection and LPS administration at higher doses in rodents, this low dose endotoxemia in the monkey is the first paradigm to produce a neural phenotype associated with augmented gray and white matter growth.

Mood disorders and their pharmacological treatment during pregnancy: is the future child affected?

Nearly half the US population will meet criteria for a neuropsychiatric disorder at some point in their lives, and 1 in 17 has a seriously debilitating illness. Although not all affected adults had an identified disorder as a child, increasingly these psychopathologies are conceptualized as the late-stage culmination of aberrant developmental processes shaped by a complex interplay of genes and experience, including experiences in utero. Decades of studies with pregnant animals demonstrate that stress-elicited perturbations in maternal biology affect offspring neurodevelopment. Studies of stress in pregnant women largely mirror these findings. Pregnant women with anxiety and/or depression experience greater life stress, and illness-related alterations in their neurobiology, with a potential to impact fetal neurobehavioral development via associated changes in the intrauterine environment and/or pharmacologic interventions. This article critically reviews findings on child development (including fetal neurobehavior) related to maternal depression, anxiety, and pharmacological treatments, primarily selective serotonin reuptake inhibitors (SSRIs). The hypothesis under review is that, in addition to genetics and characteristics of the postnatal environment, the familial transmission of risk for neuropsychiatric disorders involves a "third path"-prenatal exposure to psychiatric illness and its treatment.

Prenatal programming of human neurological function

The human placenta expresses the genes for proopiomelanocortin and the major stress hormone, corticotropin-releasing hormone (CRH), profoundly altering the "fight or flight" stress system in mother and fetus. As pregnancy progresses, the levels of these stress hormones, including maternal cortisol, increase dramatically. These endocrine changes are important for fetal maturation, but if the levels are altered (e.g., in response to stress), they influence (program) the fetal nervous system with long-term consequences. The evidence indicates that fetal exposure to elevated levels of stress hormones (i) delays fetal nervous system maturation, (ii) restricts the neuromuscular development and alters the stress response of the neonate, (iii) impairs mental development and increases fearful behavior in the infant, and (iv) may result in diminished gray matter volume in children. The studies reviewed indicate that fetal exposure to stress peptides and hormones exerts profound programming influences on the nervous system and may increase the risk for emotional and cognitive impairment.

Annual Research Review: Prenatal stress and the origins of psychopathology: an evolutionary perspective

If a mother is stressed or anxious while pregnant her child is more likely to show a range of symptoms such as those of attention deficit hyperactivity disorder, conduct disorder, aggression or anxiety. While there remains some debate about what proportion of these effects are due to the prenatal or the postnatal environment, and the role of genetics, there is good evidence that prenatal stress exposure can increase the risk for later psychopathology. Why should this be? In our evolutionary history it is possible that some increase in these characteristics in some individuals was adaptive in a stressful environment, and that this type of fetal programming prepared the child or group for the environment in which they were going to find themselves. Anxiety may have been associated with increased vigilance, distractible attention with more perception of danger, impulsivity with more exploration, conduct disorder with a willingness to break rules, and aggression with the ability to fight intruders or predators. This adaptation for a future dangerous environment may explain why stress and anxiety, rather than depression, seem to have these programming effects; why there is a dose-response relationship with prenatal stress from moderate to severe and it is not only toxic stress that has consequences; why not all children are affected and why individual children are affected in different ways; and why the outcomes affected can depend on the sex of the offspring. An evolutionary perspective may give a different understanding of children in our society with these symptoms, and suggest new directions for research. For example, there is some evidence that the type of cognitive deficits observed after prenatal stress have specific characteristics; these may be those which were adaptive in a past environment.

Psychological science on pregnancy: stress processes, biopsychosocial models, and emerging research issues

Psychological science on pregnancy is advancing rapidly. A major focus concerns stress processes in pregnancy and effects on preterm birth and low birth weight. The current evidence points to pregnancy anxiety as a key risk factor in the etiology of preterm birth, and chronic stress and depression in the etiology of low birth weight. Key mediating processes to which these effects are attributed, that is neuroendocrine, inflammatory, and behavioral mechanisms, are examined briefly and research on coping with stress in pregnancy is examined. Evidence regarding social support and birth weight is also reviewed with attention to research gaps regarding mechanisms, partner relationships, and cultural influences. The neurodevelopmental consequences of prenatal stress are highlighted, and resilience resources among pregnant women are conceptualized. Finally, a multilevel theoretical approach for the study of pregnancy anxiety and preterm birth is presented to stimulate future research.

Prenatal anxiety associated with male child preference among expectant mothers at 10-20 weeks of pregnancy in Xiangyun County, China

OBJECTIVE

To examine the relationship between male child preference and maternal prenatal psychological distress among expectant mothers from Xiangyun County, Yunnan Province, China.

METHODS

Child gender preference, state-trait anxiety and depression, relationships with the husband and mother-in-law, and self-esteem were measured in a sample of 198 women between 10 and 20 weeks of pregnancy. Multivariate logistic regression analysis was used to identify risk factors for prenatal anxiety.

RESULTS

Prenatal anxiety was correlated with male child preference (r=0.15, P<0.05), maternal age (r=-0.17, P<0.05), level of education (r=-0.23, P<0.01), self-esteem (r=-0.36, P<0.01), relationship with mother-in-law (r=-0.34, P<0.01), and relationship with husband (r=-0.35, P<0.01). Significant relationships were maintained in multivariate analysis that included gender preference, maternal education, pregnancy anxiety, self-esteem, number of people in the household, and relationship with husband as predictors (adjusted r(2)=0.28, P<0.001).

CONCLUSION

Male child preference was associated with prenatal anxiety in this sample. Younger maternal age, lower self-esteem, lower level of education, worse relationship with husband, and less family cohesiveness were also related to prenatal anxiety. Expectant mothers experienced prenatal anxiety when there was strong family preference for sons.

Pregnancy is associated with psychiatric symptoms in a low-income countryside community of Brazil

BACKGROUND

Psychiatric symptoms during pregnancy induce an increase in morbidity and also in the mortality levels among women and children. However, the real association between pregnancy and psychiatric disorders and the peculiarities of the phenomenology of symptoms in underprivileged countryside communities remain uncertain.

OBJECTIVE

To verify the association between psychiatric disorder, symptoms, and pregnancy among women from a low-income countryside community and to determine the specific cutoff points for major depression diagnosis according to Beck Depression Inventory for the different trimesters of pregnancy in this population.

METHODS

Ninety-four pregnant women and 38 healthy women from the Conceição do Mato Dentro health service, a rural low-income community in Brazil, participated in the present study. Psychiatric examination included a structured clinical interview for psychiatric disorders according to Mini International Neuropsychiatric Interview and psychometric scales such as the Yale-Brown Obsessive Scale, the Beck Depression Inventory, and the Hamilton Anxiety Scale. The cutoff points for Beck Depression Inventory were determined through the application of receiver operating characteristic curves considering the diagnosis of major depression according to Mini International Neuropsychiatric Interview.

RESULTS

The pregnant women had a higher frequency of psychiatric disorders and depression and anxiety symptoms. All cutoff points of Beck Depression Inventory were equal or higher than 12 with high sensitivity and specificity. Although the modified cutoff was selected based on both high sensitivity and high specificity, they were lower than when the cutoff was applied to nonpregnant women.

CONCLUSION

Pregnancy was associated with the occurrence of psychiatric disorders and depressive and anxiety symptoms. In comparison to the literature, the present results indicate that there are different cutoff points in the Beck Depression Inventory for pregnant women from different cultures and in different pregnancy trimesters.

Prenatal stress and developmental programming of human health and disease risk: concepts and integration of empirical findings

PURPOSE OF REVIEW

The concept of the developmental origins of health and disease susceptibility is rapidly attracting interest and gaining prominence as a complementary approach to understanding the causation of many complex common disorders that confer a major burden of disease; however several important issues and questions remain to be addressed, particularly in the context of humans.

RECENT FINDINGS

In this review we enunciate some of these questions and issues, review empirical evidence primarily from our own recent studies on prenatal stress and stress biology, and discuss putative maternal-placental-fetal endocrine and immune/inflammatory candidate mechanisms that may underlie and mediate short-term and long-term effects of prenatal stress on the developing human embryo and fetus, with a specific focus on body composition, metabolic function, and obesity risk.

SUMMARY

The implications for research and clinical practice are discussed with a summary of recent advances in noninvasive methods to characterize fetal, newborn, infant, and child developmental and health-related processes that, when coupled with available state-of-the-art statistical modeling approaches for longitudinal, repeated measures time series analysis, now afford unprecedented opportunities to explore and uncover the developmental origins of human health and disease.

Maternal stress induces long-lasting Purkinje cell developmental impairments in mouse offspring

A number of clinical studies suggest that prenatal stress can be a risk factor in the development of various psychopathologies, including schizophrenia, depression, anxiety, and autism. The cerebellar vermis has been shown to be involved in most of these disorders. In the present study, therefore, we evaluate the effect of maternal stress on long-term alterations in vermal Purkinje cell morphology. Furthermore, to discern whether these structural changes are associated with anxious behavior, the exploratory drive in the elevated plus maze was evaluated. Pregnant CF-1 mice were randomly assigned to control (n = 14) or stressed (n = 16) groups. Dams of the stressed group were subjected to restraint stress between gestational days 14 and 20, while control pregnant dams remained undisturbed in their home cages. Anxious behavior and Purkinje cell morphology were evaluated in three ontogenetic stages: postweaning, adolescence, and adulthood. Although exploratory behavior in the elevated plus maze was unaffected by prenatal stress, the Purkinje cell morphology showed a transient period of abnormal growth (at postweaning and juvenile stages) followed by dramatic dendritic atrophy in adulthood. In conclusion, prenatal stress induced significant long-lasting bimodal changes in the morphology of vermal Purkinje cells. These structural alterations, however, were not accompanied by anxious behaviors in the elevated plus maze.

Infant brain development and vulnerability to later internalizing difficulties: the Generation R study

OBJECTIVE

Although clinical studies have demonstrated smaller subcortical volumes in structures such as the amygdala, hippocampus, caudate nucleus, and thalamus in adults and adolescents with depressive disorders and anxiety, no study has assessed such structures in babies, long before the development of the disorders. This study examined whether the size of the "gangliothalamic ovoid" (encompassing the basal ganglia and thalamus) assessed during infancy is associated with increased internalizing problems in early childhood.

METHOD

Cranial ultrasounds were used to assess gangliothalamic ovoid diameter and ventricular volume at 6 weeks of postnatal age; moreover, head circumference was measured. Outcome data included ratings of internalizing and externalizing problems using the Child Behavior Checklist (reported by mothers and fathers) at 18 and/or 36 months. Analyses were based on a total of 651 children.

RESULTS

Smaller gangliothalamic diameter was associated with higher Child Behavior Checklist Internalizing scores at ages 18 and 36 months. Results remained significant after correcting for head circumference and were evident for the DSM-oriented subscales of anxiety problems and affective problems. Total ventricular volume was not consistently associated with Internalizing scores.

CONCLUSIONS

Findings associating infant brain measurements with Child Behavior Checklist mother and father reports at two time points are consistent with previous cross-sectional reports of smaller subcortical volumes in depression. Results were not simply reflective of overall brain development, because the pattern held after adjustment for head circumference. This is the first study to point toward a biological vulnerability evident in infancy, involved in the development of internalizing problems in childhood.

Gestational stress influences cognition and behavior

The developmental origins of disease or fetal programming model predicts that early exposures to threat or adverse conditions have lifelong consequences that result in harmful outcomes for health. The vast majority of the studies in support of the programming model in human beings are retrospective and most rely on surrogate measures of early experience such as birth weight or preterm birth. Recently, a small number of prospective studies have been reported that have documented the developmental consequences of exposures to stressful intrauterine conditions. These studies of gestational stress have clearly shown that fetal exposures to psychosocial and/or biological markers of adversity have significant and largely negative consequences for fetal, infant and child neurological development. Fetal exposure to stress, especially early in gestation, results in delayed fetal maturation and impaired cognitive performance during infancy and results in decreased brain volume in areas associated with learning and memory in children. The accumulating evidence supports the conclusion that fetal exposure to stress profoundly influences the nervous system, with consequences that persist into childhood and perhaps beyond.

Does ageing originate in utero?

Ageing still remains a conundrum on the cellular and molecular level, while environmental factors and interactions further increase the complexity of the ageing process. On the other hand is cancer, for which 20 years ago, it was proposed by Trichopoulos that it might have intrauterine origin. We herein discuss the idea that parameters such as the influence of insulin-like growth factor (IGF) signalling, of hormones and of the number of stem cells, as well as the effect of foetal and early life nutrition on ageing may also commence in utero and we provide epidemiological and biological data to advocate for this hypothesis. Finally, we analyse the public health implication of this hypothesis based on the World Health Organization (WHO) report that the burden of diseases, including ageing, may be due to impaired foetal development.

Prenatal stress and brain development

Prenatal stress (PS) has been linked to abnormal cognitive, behavioral and psychosocial outcomes in both animals and humans. Animal studies have clearly demonstrated PS effects on the offspring's brain, however, while it has been speculated that PS most likely affects the brains of exposed human fetuses as well, no study has to date examined this possibility prospectively using an independent stressor (i.e., a stressful event that the pregnant woman has no control over, such as a natural disaster). The aim of this review is to summarize the existing animal literature by focusing on specific brain regions that have been shown to be affected by PS both macroscopically and microscopically. These regions include the hippocampus, amygdala, corpus callosum, anterior commissure, cerebral cortex, cerebellum and hypothalamus. We first discuss the mechanisms by which the effects of PS might occur. In particular, we show that maternal and fetal hypothalamic-pituitary-adrenal (HPA) axes, and the placenta, are the most likely candidates for these mechanisms. We see that, although animal studies have obvious advantages over human studies, the integration of findings in animals and the transfer of these findings to human populations remains a complex issue. Finally, we show how it is possible to circumvent these challenges by studying the effects of PS on brain development directly in humans, by taking advantage of natural or man-made disasters and assessing the impact and consequences of such stressful events on pregnant women and their offspring prospectively.