Prenatal Exposure to an Acute Stressor and Children's Cognitive Outcomes

Maternal stress during pregnancy alters circulating small extracellular vesicles and enhances their targeting to the placenta and fetus

BACKGROUND

Maternal psychological distress during pregnancy can negatively impact fetal development, resulting in long-lasting consequences for the offspring. These effects show a sex bias. The mechanisms whereby prenatal stress induces functional and/or structural changes in the placental-fetal unit remain poorly understood. Maternal circulating small extracellular vesicles (sEVs) are good candidates to act as "stress signals" in mother-to-fetus communication. Using a repetitive restraint-based rat model of prenatal stress, we examined circulating maternal sEVs under stress conditions and tested whether they could target placental-fetal tissues.

RESULTS

Our mild chronic maternal stress during pregnancy paradigm induced anhedonic-like behavior in pregnant dams and led to intrauterine growth restriction (IUGR), particularly in male fetuses and placentas. The concentration and cargo of maternal circulating sEVs changed under stress conditions. Specifically, there was a significant reduction in neuron-enriched proteins and a significant increase in astrocyte-enriched proteins in blood-borne sEVs from stressed dams. To study the effect of repetitive restraint stress on the biodistribution of maternal circulating sEVs in the fetoplacental unit, sEVs from pregnant dams exposed to stress or control protocol were labeled with DiR fluorescent die and injected into pregnant females previously exposed to control or stress protocol. Remarkably, maternal circulating sEVs target placental/fetal tissues and, under stress conditions, fetal tissues are more receptive to sEVs.

CONCLUSION

Our results suggest that maternal circulating sEVs can act as novel mediators/modulators of mother-to-fetus stress communication. Further studies are needed to identify placental/fetal cellular targets of maternal sEVs and characterize their contribution to stress-induced sex-specific placental and fetal changes.

Separating Scarring Effect and Selection of Early-Life Exposures With Genetic Data

Causal life course research examining consequences of early-life exposures has largely relied on associations between early-life environments and later-life outcomes using exogenous environmental shocks. Nonetheless, even with (quasi-)randomized early-life exposures, these associations may reflect not only causation ("scarring") but also selection (i.e., which members are included in data assessing later life). Investigating this selection and its impacts on estimated effects of early-life conditions has, however, often been ignored because of a lack of pre-exposure data. This study proposes an approach for assessing and correcting selection, separately from scarring, using genetic measurements. Because genetic measurements are determined at the time of conception, any associations with early-life exposures should be interpreted as selection. Using data from the UK Biobank, we find that in utero exposure to a higher area-level infant mortality rate is associated with genetic predispositions correlated with better educational attainment and health. These findings point to the direction and magnitude of selection from this exposure. Corrections for this selection in examinations of effects of exposure on later educational attainment suggest underestimates of 26-74%; effects on other life course outcomes also vary across selection correction methods.

The Effects of the Flint water crisis on the educational outcomes of school-age children

In 2014, the municipal water source in Flint, Michigan was switched, causing lead from aging pipes to leach into the city's drinking water. While lead exposure in Flint children increased modestly on average, some children were exposed to high lead levels. Surveys of Flint residents show the water crisis was also associated with increased levels of stress, anxiety, and depression. We use Michigan's administrative education data and utilize synthetic control methods to examine the impact of the crisis on Flint's school-age children. We find decreases in math achievement and increases in special needs classification, even among children living in homes with copper (rather than lead) water service lines. Low socioeconomic status students and younger students experienced the largest effects on math achievement, and boys experienced the largest effects on special needs classification. Our results point toward the broad negative effects of the crisis on children and suggest that existing estimates may substantially underestimate the overall societal cost of the crisis.

Dust to Feed, Dust to Gray: The Effect of in Utero Exposure to the Dust Bowl on Old-Age Longevity

Intensive agriculture and deep plowing caused topsoil erosion and dust storms during the 1930s, affecting agricultural income and land values for years. Given the growing literature on the relevance of in utero and early-life exposures, it is surprising that studies focusing on links between the Dust Bowl and later-life health have produced inconclusive and mixed results. We reevaluate this literature and study the long-term effects of in utero and early-life exposure to topsoil erosion caused by the 1930s Dust Bowl on old-age longevity. Specifically, using Social Security Administration death records linked with the full-count 1940 census, we conduct event studies with difference-in-differences designs to compare the longevity of individuals in high- versus low-topsoil-erosion counties before versus after 1930. We find intent-to-treat reductions in longevity of approximately 0.85 months for those born in high-erosion counties after 1930. We show that these effects are not an artifact of preexisting trends in longevity. Additional analyses suggest that the effects are more pronounced among children raised in farm households, females, and those whose mothers had lower education. We also provide suggestive evidence that reductions in adulthood income are a likely mechanism for the effects we document.

A Time of Healing: Can Social Engagement After Bereavement Reduce Trajectories of Depression After the Death of a Child?

OBJECTIVES

We work from a stress and life-course perspective to examine the mental health of parents who experienced the death of their child. We examine whether mental health eventually returns to pre-bereavement levels and how social engagement after bereavement may shape the recovery process of depressive symptoms.

METHODS

We analyze discontinuous growth curve models to assess the association between a child's death and trajectories of parents' depressive symptoms from the 1998-2016 Health and Retirement Study. The sample includes 16,182 parents aged 50 years and older.

RESULTS

Those who transitioned to bereavement experienced an elevation in depressive symptoms and a relatively long recovery time (e.g., 7 years) to their pre-bereavement mental health in our findings. However, when engaging in volunteer work after their loss, depressive symptoms reduce more quickly to their pre-bereavement levels. Volunteering offsets up to 3 years of the negative consequences of child loss.

DISCUSSION

The death of a child is a traumatic event with extensive health consequences, but research should more fully examine the dynamic nature and potential mitigation of these health consequences over time. Our findings expand the temporal lens to encompass healing processes after bereavement, incorporating the importance of social engagement.

What is prenatal stress? A scoping review of how prenatal stress is defined and measured within the context of food insecurity, housing instability, and immigration in the United States

BACKGROUND

Stress during pregnancy can lead to significant adverse outcomes for maternal mental health. Early evaluation of prenatal stress can help identify treatment needs and appropriate interventions. Disparities in the social determinants of health can contribute to stress, but what constitutes stress during pregnancy within the social determinants of health framework is poorly understood.

OBJECTIVE

To scope how prenatal stress is defined and measured among pregnant people exposed to three prominent social stressors in the United States: insecurity pertaining to food, housing, and immigration.

ELIGIBILITY CRITERIA

We included all studies that focused on stress during pregnancy in the context of food insecurity, housing instability, and immigration, given their recent policy focus due to the COVID-19 pandemic and ongoing political discourse, in addition to their importance in American College of Obstetricians and Gynecologists (ACOG's) social determinants of health screening tool.

SOURCES OF EVIDENCE

We searched PubMed, Scopus, and Web of Science for articles published between January 2012 and January 2022.

CHARTING METHODS

Using a piloted charting tool, we extracted relevant study information from the selected articles and analyzed the content pertaining to stress.

RESULTS

An initial search identified 1,023 articles, of which 24 met our inclusion criteria. None of the studies defined prenatal stress, and only one used the Prenatal Distress Questionnaire, a prenatal stress-specific tool to measure it. The Perceived Stress Scale was the most common instrument used in seven studies. Fifteen studies measured over 25 alternative exposures that researchers theorized were associated with stress, and 4 of the 15 studies did not explain the association between the measure and stress.

CONCLUSIONS

Our findings demonstrate a fundamental inconsistency in how prenatal stress is defined and measured in the context of social determinants of health, limiting the comparison of results across studies and the potential development of effective interventions to promote better maternal mental health.

How Maternal Trauma Exposure Contributed to Children's Depressive Symptoms following the Wenchuan Earthquake: A Multiple Mediation Model Study

Although well-established literature has indicated the burden of mental health among victims after the Wenchuan earthquake, no research has focused on the mental health of mothers and their children who experienced the earthquake and were pregnant during or shortly after it. This study investigates the relationship between maternal trauma exposure (TE) and children's depressive symptoms after the Wenchuan earthquake and explores the risk and protective factors underlying this relationship. A sample of 547 mother-child dyads, in which the mother experienced the Wenchuan earthquake, was used to assess maternal depressive symptoms, maternal TE, children's depressive symptoms, children's perceived impact of the earthquake and maternal posttraumatic growth (PTG). The results showed that maternal TE had two significant one-step indirect associations with children's depressive symptoms (through children's perceived impact of the earthquake and maternal PTG) and one two-step indirect association with children's depressive symptoms (through maternal depressive symptoms via children's perceived impact of the earthquake). The results indicated that maternal depressive symptoms, children's perceived impact of the earthquake and maternal PTG mediated the association between maternal TE and children's depressive symptoms. These findings highlight the importance of mothers in supporting the mental health of these children. Maternal depressive symptoms and PTG, two posttraumatic outcomes, played positive and negative roles in the intergenerational transmission of trauma. Thus, post-disaster interventions should reduce the maternal transmission of trauma-related information and improve maternal PTG to support children's mental health.

The Unequal Impact of the COVID-19 Pandemic on Infant Health

The COVID-19 pandemic has taken a large toll on population health and well-being. We examine the consequences of prenatal exposure for infant health, through which the pandemic may have lasting intergenerational effects. We examine multiple pathways by which the pandemic shaped birth outcomes and socioeconomic disparities in these consequences. Analysis of more than 3.5 million birth records in California with universal information on COVID infection among persons giving birth at the time of delivery reveals deep inequalities in infection by education, race/ethnicity, and place-based socioeconomic disadvantage. COVID infection during pregnancy, in turn, predicts a large increase in the probability of preterm birth, by approximately one third. At the population level, a surprising reduction in preterm births during the first months of the pandemic was followed by an increase in preterm births during the surge in COVID infections in the winter of 2021. Whereas the early-pandemic reduction in preterm births benefited primarily highly educated mothers, the increase in preterm births during the winter infection surge was entirely concentrated among mothers with low levels of schooling. The COVID-19 pandemic is expected to exacerbate U.S. inequality in multiple ways. Our findings highlight a particularly enduring pathway: the long-term legacy of prenatal exposure to an unequal pandemic environment.

Unequal effects of disruptive events

Disruptive events have significant consequences for the individuals and families who experience them, but these effects do not occur equally across the population. While some groups are strongly affected, others experience few consequences. We review recent findings on inequality in the effects of disruptive events. We consider heterogeneity based on socioeconomic resources, race/ethnicity, the likelihood of experiencing disruption, and contextual factors such as the normativity of the event in particular social settings. We focus on micro-level events affecting specific individuals and families, including divorce, job loss, home loss and eviction, health shocks and deaths, and violence and incarceration, but also refer to macro-level events such as recession and natural disasters. We describe patterns of variation that suggest a process of resource disparities and cumulative disadvantage versus those that reflect the impact of non-normative and unexpected shocks. Finally, we review methodological considerations when examining variation in the effect of disruptive events.

The impact of unemployment benefits on birth outcomes: Quasi-experimental evidence from European linked register data

Cash transfers have been shown to improve birth outcomes by improving maternal nutrition, increasing healthcare use, and reducing stress. Most of the evidence focuses on programs targeting the poorest in the US-a context with non-universal access to healthcare and strong health inequalities. It is thus unclear whether these results would apply to cash transfers targeting a less disadvantaged population and whether they apply to other contexts. We provide evidence on the impact of unemployment benefits on birth outcomes in Switzerland, where access to healthcare is near-universal and social assistance is relatively generous. Our study taps into a policy reform that reduced unemployment benefits by 56%. We use linked parent-child register data and difference-in-differences estimates as well as within sibling comparisons. We find that the reform did not impact birth outcomes when fathers were unemployed but reduced the birthweight of children when mothers were unemployed by 80g and body length by 6mm. There are stronger effects for children whose mothers were the primary earner before job loss, but effects do not differ systematically by household income. These results suggest that in the Swiss context, unemployment benefits improve birth outcomes by reducing (job search) stress rather than by improving nutrition or healthcare use. As such, cash transfers likely play a role for newborn health in most other contexts.

Maternal stress during pregnancy and early childhood development

We estimate the impact of prenatal stress on early childhood development outcomes known as "middle years" or intermediate outcomes, which has not been studied previously. Using a unique measure of actual maternal stress induced by a large earthquake, we find that relative to children that were not exposed, in utero maternal stress reduces children's cognitive skills and socio-emotional problems by age 3, and that the effects are heterogeneous. The negative impacts on cognitive skills occur during the first trimester of pregnancy and are found among both low and high-income children, and boys and girls. The harmful effects on socio-emotional behaviors occur when stress is experienced in the last trimester of pregnancy.

Does postponing retirement affect cognitive function? A counterfactual experiment to disentangle life course risk factors

Evidence suggests that contemporaneous labor force participation affects cognitive function; however, it is unclear whether it is employment itself or endogenous factors related to individuals’ likelihood of employment that protects against cognitive decline. We exploit innovations in counterfactual causal inference to disentangle the effect of postponing retirement on later-life cognitive function from the effects of other life-course factors. With the U.S. Health and Retirement Study (1996–2014, n = 20,469), we use the parametric g-formula to estimate the effect of postponing retirement to age 67. We also study whether the benefit of postponing retirement is affected by gender, education, and/or occupation, and whether retirement affects cognitive function through depressive symptoms or comorbidities. We find that postponing retirement is protective against cognitive decline, accounting for other life-course factors (population: 0.34, 95% confidence interval (CI): 0.20,0.47; individual: 0.43, 95% CI: 0.26,0.60). The extent of the protective effect depends on subgroup, with the highest educated experiencing the greatest mitigation of cognitive decline (individual: 50%, 95% CI: 32%,71%). By using innovative models that better reflect the empirical reality of interconnected life-course processes, this work makes progress in understanding how retirement affects cognitive function.

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Research is inconclusive as to employments' protection against cognitive decline.

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Causal inference models can better reflect interconnected life-course processes.

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The parametric g-formula shows a substantial protective effect of ongoing employment.

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Protective effect holds for all subgroups, but is greatest for the highest educated.

Maternal exposure to a high-magnitude earthquake during pregnancy influences pre-reading skills in early childhood

Exposure to an adverse prenatal environment can influence fetal development and result in long-lasting changes in the offspring. However, the association between maternal exposure to stressful events during pregnancy and the achievement of pre-reading skills in the offspring is unknown. Here we examined the association between prenatal exposure to the Chilean high-magnitude earthquake that occurred on February 27th, 2010 and the development of early reading precursors skills (listening comprehension, print knowledge, alphabet knowledge, vocabulary, and phonological awareness) in children at kindergarten age. This multilevel retrospective cohort study including 3280 children, of whom 2415 were unexposed and 865 were prenatally exposed to the earthquake shows substantial evidence that maternal exposure to an unambiguously stressful event resulted in impaired pre-reading skills and that a higher detrimental effect was observed in those children who had been exposed to the earthquake during the first trimester of gestation. In addition, females were more significantly affected by the exposure to the earthquake than their male peers in alphabet knowledge; contrarily, males were more affected than females in print knowledge skills. These findings suggest that early intervention programs for pregnant women and/or children exposed to prenatal stress may be effective strategies to overcome impaired pre-reading skills in children.

The cognitive development from childhood to adolescence of low birthweight children born after medically assisted reproduction-a UK longitudinal cohort study

Background

Previous research has documented that children conceived through medically assisted reproduction (MAR) are at increased risk of poor birth outcomes, such as low birthweight (LBW), which are risk factors for stunted longer-term cognitive development. However, parents who undergo MAR to conceive have, on average, advantaged socioeconomic backgrounds which could compensate for the negative effects of being born LBW. Previous studies have not analysed whether the negative effects of LBW are attenuated among MAR conceived children.

Methods

We draw on the UK Millennium Cohort Study (sweeps 1–6) which contains a sub-sample of (N = 396) MAR-conceived children. The dependent variable measures cognitive ability at around ages 3, 5, 7, 11 and 14. We examine the cognitive development of four groups of children: MAR-conceived low birthweight (MAR LBW); MAR-conceived non-low birthweight (MAR NLBW); naturally conceived low birthweight (NC LBW); naturally conceived non-low birthweight (NC NLBW). We estimate the two following linear regression models for each sweep: (i) a baseline model to examine the unadjusted association between cognitive development and low birthweight by mode of conception; and (ii) a model adjusted by socio-demographic family characteristics.

Results

In baseline models, MAR LBW children [age 3: β  =  0.021, 95% confidence interval (CI): -0.198, 0.241; age 5: β  =  0.21, 95% CI: 0.009, 0.418; age 7: β  =  0.163, 95% CI: -0.148, 0.474; age 11: β  =  0.003, 95% CI: -0.318, 0.325; age 14: β  =  0.156, 95% CI: -0.205, 0.517], on average perform similarly in cognitive ability relative to NC NLBW at all ages, and display higher cognitive scores than NC LBW children until age 7. When we account for family characteristics, differences are largely attenuated and become close to zero at age 14.

Conclusions

Despite the higher incidence of LBW among MAR compared with NC children, they do not seem to experience any disadvantage in their cognitive development compared with naturally conceived children. This finding is likely explained by the fact that, on average, MAR children are born to socioeconomically advantaged parents.

What is the causal effect of income gains on youth obesity? Leveraging the economic boom created by the Marcellus Shale development

Low family income is frequently assumed to be a primary social determinant of youth obesity in the U.S. But while the observed correlation between family income and youth obesity is consistently negative, the true causal relationship is unclear. I take advantage of a natural experiment - the boom economy created by development of the Marcellus Shale geological formation for natural gas extraction - to study whether income gains affect youth obesity rates among Pennsylvania students. To test this relationship, I compile data from geological, administrative, Census and other governmental sources and estimate cross-sectional OLS regression models, longitudinal fixed effects models, and two-stage instrumental variable models within a difference-in-differences framework. Falsification tests indicate that children's location relative to the Marcellus Shale's geological boundaries is a valid instrument for income gains. Yet plausibly exogenous income gains do not alter youth obesity rates, regardless of the community's initial level of poverty or affluence and regardless of the child's grade level. Thus, the observed disparities in youth obesity by area income in Pennsylvania do not result from simple differences in disposable income and the relative cost of "healthy" versus "unhealthy" goods and services.

Maternal stress and birth outcomes: Evidence from an unexpected earthquake swarm

We examine the impact of a major earthquake that unexpectedly affected the Canterbury region of New Zealand on a wide-range of birth outcomes, including birth weight, gestational age, and an indicator of general newborn health. We control for observed and unobserved differences between pregnant women in the area affected by the earthquake and other pregnant women by including mother fixed effects in all of our regression models. We extend the previous literature by comparing the impact of the initial unexpected earthquake to the impacts of thousands of aftershocks that occurred in the same region over the 18 months following the initial earthquake. We find that exposure to these earthquakes reduced gestational age, increased the likelihood of having a late birth, and negatively affected newborn health-with the largest effects for earthquakes that occurred in the first and third trimesters of pregnancy. Our estimates are similar when we focus on just the impact of the initial earthquake or, in contrast, on all earthquakes controlling for endogenous location decisions using an instrumental variables approach. This suggests that the previous estimates in the literature that use this approach are likely unbiased and that treatment effects are homogenous in the population. We present supporting evidence that the likely channel for these adverse effects is maternal stress.

Police violence and the health of black infants

Police use of force is a controversial issue, but the broader consequences and spillover effects are not well understood. This study examines the impact of in utero exposure to police killings of unarmed blacks in the residential environment on black infants' health. Using a preregistered, quasi-experimental design and data from 3.9 million birth records in California from 2007 to 2016, the findings show that police killings of unarmed blacks substantially decrease the birth weight and gestational age of black infants residing nearby. There is no discernible effect on white and Hispanic infants or for police killings of armed blacks and other race victims, suggesting that the effect reflects stress and anxiety related to perceived injustice and discrimination. Police violence thus has spillover effects on the health of newborn infants that contribute to enduring black-white disparities in infant health and the intergenerational transmission of disadvantage at the earliest stages of life.

The prevalence and risk of DSM-IV axis I disorder in adults with early-life earthquake stress: A cross-sectional study

OBJECTIVES

Tangshan earthquake which had a magnitude of 7.8 killed approximately 250,000 people in China in 1976. In the present study, we sought to determine the prevalence and risks of mental disorders in adults who experienced earthquake as an infant or in the prenatal period.

METHODS

This cross-sectional cohort study recruited participants based on the urban resident registry of Tangshan, Hebei province, 2013 using a multistage stratified cluster sampling method with selection probabilities proportional to size. We recruited subjects who were born between July 29, 1975 and April 28, 1978 that was one year before and 1.9 years after the occurrence of Tangshan Earthquake, respectively. Current psychiatric diagnoses and lifetime psychiatric diagnoses were obtained through the Structured Clinical Interview for DSM-IV Axis I Disorders Patient Research Version. Unconditional logistic regression analysis was performed to analyze risk factors of mental disorders.

RESULTS

Totally1380 subjects were included with 392 subjects exposed to the earthquake in the fetal period, 399 subjects who experienced the earthquake during their infancy, and 589 subjects who had no exposure to the earthquake. Twenty-one (2.7%; current 1.9%) subjects exposed to earthquake were diagnosed with major depressive disorderversus 2.3% (current 1.5%) in the non-exposure group. Five (0.6%; current 0.6%) subjects with exposure to earthquake had bipolar disorder versus 0.9% in the non-exposure group.Thirteen (1.6%; current 1.6%) subjects with exposure to earthquake had schizophreniaversus 0.2% in the non-exposure group (P=0.006). Furthermore, 5.2% (current 3.7%) subjects with exposure to earthquake had anxiety disorders versus 5.7% (current 3.9%) in the non-exposure group. Moreover, 8.1% (current 7.0%)subjects with exposure to earthquake had alcohol use disorders versus 7.1% (current 5.3%) in the non-exposure group. Furthermore, the prevalence of schizophrenia of the prenatal exposure group (2.3%) was significantly higher than the other two groups (χ² = 10.273, P = 0.006); however, no statistically significant difference was found in the current and lifetime prevalence of other DSM-IV axis I disorders among the three groups (P > 0.05). Our multivariate regression analysis showed that prenatal earthquake stress exposure was not a significant risk of any of the lifetime or current DSD-IV axis I disorders.

CONCLUSION

Adults who were exposed to earthquake in the prenatal period had a significantly higher rate of schizophrenia than those who were not exposed or who experienced earthquake in their infancy. No statistically significant difference was found in the current and lifetime prevalence of other DSM-IV axis I disorders between those exposed and those not exposed to earthquake. Furthermore, prenatal earthquake stress exposure was not a significant risk of any of the lifetime or current DSD-IV axis I disorders.

Climate change and educational attainment in the global tropics

Climate change may negatively impact education among children via exposure to extreme temperature and precipitation conditions. We link census data from 29 countries across the global tropics to high-resolution gridded climate data to understand how climatic conditions experienced in utero and during early childhood affect educational attainment at ages 12 to 16. We show that exposure to higher-than-average temperatures during the prenatal and early-life period is associated with fewer years of schooling in Southeast Asia. In this region, a child who experiences temperatures 2 SDs above average is predicted to attain 1.5 fewer years of schooling than one who experiences average temperatures. In addition, early-life rainfall is positively correlated with attainment in West and Central Africa as well as Southeast Asia, and negatively correlated with attainment in Central America and the Caribbean. While we expected that children from the most educated households would be buffered from these effects, we discover that they tend to experience the greatest educational penalties when exposed to hotter early-life conditions and, in some regions, to drier conditions. For example, among the most educated households in West and Central Africa, predicted schooling is 1.8 years lower for children who experience early-life rainfall 2 SDs below average versus 2 SDs above average, while the difference is just 0.8 years for children from the least educated households. These results suggest that development and educational gains in the tropics could be undermined by climate change, even for better-off households.