Sexually dimorphic adaptations in basal maternal stress physiology during pregnancy and implications for fetal development

Urinary phenol and paraben concentrations in association with markers of inflammation during pregnancy in Puerto Rico

Exposure to phenols and parabens may contribute to increased maternal inflammation and adverse birth outcomes, but these effects are not well-studied in humans. This study aimed to investigate relationships between concentrations of 8 phenols and 4 parabens with 6 inflammatory biomarkers (C-reactive protein (CRP); matrix metalloproteinases (MMP) 1, 2, and 9; intercellular adhesion molecule-1 (ICAM-1); and vascular cell adhesion molecule-1 (VCAM-1)) measured at two time points in pregnancy in the PROTECT birth cohort in Puerto Rico. Linear mixed models were used, adjusting for covariates of interest. Results are expressed as the percent change in outcome per interquartile range (IQR) increase in exposure. Particularly among phenols, numerous significant negative associations were found, for example, between benzophenone-3 and CRP (-11.21 %, 95 % CI: -17.82, -4.07) and triclocarban and MMP2 (-9.87 %, 95 % CI: -14.05, -5.5). However, significant positive associations were also detected, for instance, between bisphenol-A (BPA) and CRP (9.77 %, 95 % CI: 0.67, 19.68) and methyl-paraben and MMP1 (10.78 %, 95 % CI: 2.17, 20.11). Significant interactions with female fetal sex and the later study visit (at 24-28 weeks gestation) showed more positive associations compared to male fetal sex and the earlier study visit (16-20 weeks gestation). Our results suggest that phenols and parabens may disrupt inflammatory processes pertaining to uterine remodeling and endothelial function, with important implications for pregnancy outcomes. More research is needed to further understand maternal inflammatory status in an effort to improve reproductive and developmental outcomes.

Adverse Childhood Experiences Predict Diurnal Cortisol Throughout Gestation

OBJECTIVE

Adverse childhood experiences (ACEs) are associated with negative prenatal and perinatal health outcomes and may, via these pathways, have intergenerational effects on child health and development. We examine the impact of ACEs on maternal salivary cortisol, a key measure of prenatal biology previously linked with pregnancy-related health outcomes.

METHODS

Leveraging assessments across three trimesters, we used linear mixed-effects models to analyze the influence of ACEs on maternal prenatal diurnal cortisol patterns in a diverse cohort of pregnant women (analytic sample, n = 207). Covariates included comorbid prenatal depression, psychiatric medications, and sociodemographic factors.

RESULTS

Maternal ACEs were significantly associated with flatter diurnal cortisol slopes (i.e., less steep decline), after adjusting for covariates, with effects consistent across gestation (estimate = 0.15, standard error = 0.06, p = .008).

CONCLUSIONS

ACEs experienced before pregnancy may have a robust and lasting influence on maternal prenatal hypothalamic-pituitary-adrenal activity throughout gestation, a key biological marker associated with perinatal and child health outcomes. The findings suggest one route of intergenerational transmission of early adverse experiences and underscore the potential value of assessing prepregnancy adverse experiences for promoting perinatal and maternal and child health.

Maternal serum cortisol levels during pregnancy differ by fetal sex

BACKGROUND

Males and females have different patterns of fetal growth, resulting in different sizes at birth. Increased maternal cortisol levels in pregnancy negatively impact fetal growth. However, it is unknown whether sexual dimorphism displays differences in maternal cortisol levels already during early pregnancy and to what extent it explains sex differences in intra-uterine growth. The present cross-sectional study investigated whether fetal sex was associated with the level of maternal serum total cortisol in first half of pregnancy and its contribution to sex differences in fetal growth.

METHOD

The study population comprised 3049 pregnant women from the Amsterdam Born Children and their Development (ABCD)-cohort). Total serum cortisol levels were determined during pregnancy. Multivariable linear regression was used to determine fetal sex differences in maternal cortisol levels and its association with sex differences in fetal growth measured as birth weight standardized for gestational age, parity and sex.

RESULTS

Maternal serum total cortisol increased during pregnancy from on average 390 ± 22 nmol/L (at 5th week) to 589 ± 15 nmol/L (at 20th week). Women carrying a female fetus had higher maternal total cortisol levels. This sex difference was not significant before the 11th week; at the 12th week the difference was 15 ± 7 nmol/L which increased to 45 ± 22 nmol/L at the 20th week (p-for-interaction=0.05). Maternal total cortisol levels were associated with birth weight (ß:-0.22;P < 0.001). However, sex differences in birth weight were not explained by related maternal total cortisol levels.

CONCLUSION

The sexual dimorphic maternal serum total cortisol levels are apparent after the first trimester but do not explain the different patterns of fetal growth.

Minimally invasive biomarkers in human and non-human primate evolutionary biology: Tools for understanding variation and adaptation

BACKGROUND

The use of minimally invasive biomarkers (MIBs - physiological biomarkers obtained from minimally invasive sample types) has expanded rapidly in science and medicine over the past several decades. The MIB approach is a methodological strength in the field of human and non-human primate evolutionary biology (HEB). Among humans and our closest relatives, MIBs provide unique opportunities to document phenotypic variation and to operationalize evolutionary hypotheses.

AIMS

This paper overviews the use of MIBs in HEB. Our objectives are to (1) highlight key research topics which successfully implement MIBs, (2) identify promising yet under-investigated areas of MIB application, and (3) discuss current challenges in MIB research, with suggestions for advancing the field.

DISCUSSION AND CONCLUSIONS

A range of MIBs are used to investigate focal topics in HEB, including energetics and life history variation/evolution, developmental plasticity, and social status and dominance relationships. Nonetheless, we identify gaps in existing MIB research on traits such as physical growth and gut function that are central to the field. Several challenges remain for HEB research using MIBs, including the need for additional biomarkers and methods of assessment, robust validations, and approaches that are standardized across labs and research groups. Importantly, researchers must provide better support for adaptation and fitness effects in hypothesis testing (e.g., by obtaining complementary measures of energy expenditure, demonstrating redundancy of function, and performing lifetime/longitudinal analyses). We point to continued progress in the use of MIBs in HEB to better understand the past, present, and future of humans and our closest primate relatives.

Fetal sex-specific epigenetic associations with prenatal maternal depressive symptoms

Prenatal maternal mental health is a global health challenge with poorly defined biological mechanisms. We used maternal blood samples collected during the second trimester from a Singaporean longitudinal birth cohort study to examine the association between inter-individual genome-wide DNA methylation and prenatal maternal depressive symptoms. We found that (1) the maternal methylome was significantly associated with prenatal maternal depressive symptoms only in mothers with a female fetus; and (2) this sex-dependent association was observed in a comparable, UK-based birth cohort study. Qualitative analyses showed fetal sex-specific differences in genomic features of depression-related CpGs and genes mapped from these CpGs in mothers with female fetuses implicated in a depression-associated WNT/β-catenin signaling pathway. These same genes also showed enriched expression in brain regions linked to major depressive disorder. We also found similar female-specific associations with fetal-facing placenta methylome. Our fetal sex-specific findings provide evidence for maternal-fetal interactions as a mechanism for intergenerational transmission.

Associations between maternal awakening salivary cortisol levels in mid-pregnancy and adverse birth outcomes

PURPOSE

Elevated levels of maternal cortisol have been hypothesized as the intermediate process between symptoms of depression and psychosocial stress during pregnancy and adverse birth outcomes. Therefore, we examined associations between cortisol levels in the second trimester of pregnancy and risks of three common birth outcomes in a nested case-control study.

METHODS

This study was embedded in the PRIDE Study (n = 3,019), from which we selected all cases with preterm birth (n = 64), low birth weight (n = 49), and small-for-gestational age (SGA; n = 65), and 260 randomly selected controls, among the participants who provided a single awakening saliva sample in approximately gestational week 19 in 2012-2016. Multivariable linear and logistic regression was performed to assess the associations between continuous and categorized cortisol levels and the selected outcomes.

RESULTS

We did not observe any associations between maternal cortisol levels and preterm birth and low birth weight. However, high cortisol levels (≥ 90th percentile) seemed to be associated with SGA (adjusted odds ratio 2.1, 95% confidence interval 0.9-4.8), in particular among girls (adjusted odds ratio 3.7, 95% confidence interval 1.1-11.9, based on eight exposed cases) in an exploratory analysis.

CONCLUSION

The results of this study showed no suggestions of associations between maternal awakening cortisol levels in mid-pregnancy and adverse birth outcomes, except for an increased risk of SGA.

The Alberta Pregnancy Outcomes and Nutrition (APrON) longitudinal study: cohort profile and key findings from the first three years

PURPOSE

The objectives of the ongoing Canadian longitudinal cohort called the Alberta Pregnancy Outcomes and Nutrition (APrON) study are to: (1) determine the relationship between maternal nutrient intake and status before, during, after pregnancy, and (a) maternal mental health, (b) pregnancy and birth outcomes, and (c) infant/child neurodevelopment and behavior; (2) identify maternal mental health and nutrient predictors of child behaviour; and (3) establish a DNA biobank to explore genomic predictors of children's neurodevelopment and behavior. The purpose of this paper is to describe the participants, measures, and key findings on maternal and paternal mental health, maternal nutrition, and child outcomes to when children are 3 years of age.

PARTICIPANTS

Participants included mothers and their children (n=2189) and mothers' partners (usually fathers; n=1325) from whom data were collected during the period from pregnancy to when children were 3 years of age, in Alberta, Canada. More than 88% of families have been retained to take part in completed data collection at 8 years of age.

FINDINGS TO DATE

Data comprise: questionnaires completed by pregnant women/mothers and their partners on mothers', fathers' and children's health; dietary interviews; clinical assessments; linkage to hospital obstetrical records; and biological samples such as DNA. Key findings on mental health, nutrition and child outcomes are presented. APrON women who consumed more selenium and omega-3 were less likely to develop symptoms of perinatal depression. Higher prenatal consumption of choline rich foods such as eggs and milk were recommended as was vitamin D supplementation for both mothers and children to meet guidelines. Couples in which both mothers and fathers were affected by perinatal depression reported lower incomes and higher maternal prenatal depressive symptoms and lower support from fathers postnatally and their children presented with the most behavioural problems. Maternal experiences of early adversity predicted increased likelihood of perinatal depression and anxiety and children's behavioural problems.

FUTURE PLANS

The APrON cohort offers a unique opportunity to advance understanding of the developmental origins of health and disease. There is a planned follow-up to collect data at 12 years of age.

Prenatal maternal distress and immune cell epigenetic profiles at 3-months of age

BACKGROUND

Prenatal maternal distress predicts altered offspring immune outcomes, potentially via altered epigenetics. The role of different kinds of prenatal maternal distress on DNA methylation profiles is not understood.

METHODS

A sample of 117 women (APrON cohort) were followed from pregnancy to the postpartum period. Maternal distress (depressive symptoms, pregnancy-specific anxiety, stressful life events) were assessed mid-pregnancy, late-pregnancy, and 3-months postpartum. DNA methylation profiles were obtained from 3-month-old blood samples. Principal component analysis identified two epigenetic components, characterized as Immune Signaling and DNA Transcription through gene network analysis. Covariates were maternal demographics, pre-pregnancy body mass index, child sex, birth gestational age, and postpartum maternal distress. Penalized regression (LASSO) models were used.

RESULTS

Late-pregnancy stressful life events, b = 0.006, early-pregnancy depressive symptoms, b = 0.027, late-pregnancy depressive symptoms, b = 0.014, and pregnancy-specific anxiety during late pregnancy, b = -0.631, were predictive of the Immune Signaling component, suggesting that these aspects of maternal distress could affect methylation in offspring immune signaling pathways. Only early-pregnancy depressive symptoms was predictive of the DNA Transcription component, b = -0.0004, suggesting that this aspect of maternal distress is implicated in methylation of offspring DNA transcription pathways.

CONCLUSIONS

Exposure timing and kind of prenatal maternal distress could matter in the prediction of infant immune epigenetic profiles.

Hair cortisol levels in pregnancy as a possible determinant of fetal sex: a longitudinal study

Stress during pregnancy has been widely studied and associated to different variables, usually with negative results for the health of the mother and the newborn, such as having a higher risk of suffering postpartum depression, premature birth, obstetrics complications or low birthweight, among others. However, there are not many lines of research that study the role that the sex of the baby plays on this specific stress and vice versa. Thus, the main objective was to analyse the relationship between the sex of the offspring and the stress of the mothers in the first trimester of pregnancy. In order to achieve this, 108 women had their biological stress measured (trough hair cortisol levels) and psychological stress evaluated (the Prenatal Distress Questionnaire (PSS), the Perceived Stress Scale (PDQ) and the Stress Vulnerability Inventory (IVE)). The results revealed significant differences in maternal hair cortisol levels in the first trimester based on the sex of the baby they had given birth to (t = -2.04; P < 0.05): the concentration of the hormone was higher if the baby was a girl (164.36:54.45-284.87 pg/mg) than if it was a boy (101.13:37.95-193.56 pg/mg). These findings show that the sex of the future baby could be conditioned, among many other variables, by the mother´s stress levels during conception and first weeks of pregnancy. Further research is needed in this area to support our findings.

Toledo-Corral C, Chavez TA, Naya CH, Johnson M, Eckel SP, Lerner D, Grubbs BH, Farzan SF, Dunton GF, Bastain TM, Breton CV. Prenatal Maternal Cortisol Levels and Infant Birth Weight in a Predominately Low-Income Hispanic Cohort

Infant birth weight influences numerous health outcomes throughout the life course including childhood obesity and metabolic morbidities. Maternal experience of stress, both before and during pregnancy, has been hypothesized to influence fetal growth and birth outcomes. However, these associations currently are not fully understood, due to conflicting results in the published literature. Salivary cortisol is often used as a biological biomarker to assess the diurnal pattern of the hypothalamic-pituitary-adrenal axis (HPA-axis) functioning. Cortisol metrics include both the total cortisol concentration secreted during waking hours, reflected by the area under the curve (AUC), and cortisol dynamics, which include the diurnal cortisol slope (DCS) and the cortisol awakening response (CAR). This study examined the association of these cortisol metrics measured during the third trimester of pregnancy and infant birth weight among 240 mother-infant dyads participating in the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) pregnancy cohort study, which is predominately comprised of Hispanic low-income women. There were no significant associations with the maternal biological stress response and infant birth weight in this study. More research is needed in larger studies to better understand how the biological stress response influences birth weight in populations facing health disparities.

Association between fetal sex and maternal plasma microRNA responses to prenatal alcohol exposure: evidence from a birth outcome-stratified cohort

Most persons with fetal alcohol spectrum disorders (FASDs) remain undiagnosed or are diagnosed in later life. To address the need for earlier diagnosis, we previously assessed miRNAs in the blood plasma of pregnant women who were classified as unexposed to alcohol (UE), heavily exposed with affected infants (HEa), or heavily exposed with apparently unaffected infants (HEua). We reported that maternal miRNAs predicted FASD-related growth and psychomotor deficits in infants. Here, we assessed whether fetal sex influenced alterations in maternal circulating miRNAs following prenatal alcohol exposure (PAE). To overcome the loss of statistical power due to disaggregating maternal samples by fetal sex, we adapted a strategy of iterative bootstrap resampling with replacement to assess the stability of statistical parameter estimates. Bootstrap estimates of parametric and effect size tests identified male and female fetal sex-associated maternal miRNA responses to PAE that were not observed in the aggregated sample. Additionally, we observed, in HEa mothers of female, but not male fetuses, a network of co-secreted miRNAs whose expression was linked to miRNAs encoded on the X-chromosome. Interestingly, the number of significant miRNA correlations for the HEua group mothers with female fetuses was intermediate between HEa and UE mothers at mid-pregnancy, but more similar to UE mothers by the end of pregnancy. Collectively, these data show that fetal sex predicts maternal circulating miRNA adaptations, a critical consideration when adopting maternal miRNAs as diagnostic biomarkers. Moreover, a maternal co-secretion network, predominantly in pregnancies with female fetuses, emerged as an index of risk for adverse birth outcomes due to PAE.

Maternal Prenatal Depression in Pregnancies With Female and Male Fetuses and Developmental Associations With C-reactive Protein and Cortisol

BACKGROUND

Prenatal depression has lasting effects on development in offspring, including later mental illness risk. Maternal responses to depression include inflammation and hypothalamic-pituitary-adrenal axis stimulation. Effects on development of cerebral inhibitory neurocircuits may differ for female and male fetuses.

METHODS

Mothers (N = 181) were assessed periodically, beginning at 16 weeks' gestation, using the Center for Epidemiologic Studies-Depression Scale. Maternal prenatal C-reactive protein and hair cortisol and cortisone levels were determined. Cortisone was determined in neonatal hair. Development of cerebral inhibitory neurocircuits was assessed in 162 1-month-old newborns by inhibition of P50 electrophysiological responses to repeated sounds.

RESULTS

Maternal depression was associated with decreased newborn P50 inhibition in both sexes. Maternal C-reactive protein levels were significantly associated with depression only in pregnancies with male fetuses and with decreased newborn P50 inhibition only in male newborns. Maternal cortisol levels were significantly associated with depression only in pregnancies with female fetuses and with decreased newborn P50 inhibition only in female newborns. In pregnancies with male fetuses compared with pregnancies with female fetuses, cortisol was more robustly metabolized to cortisone, which does not activate cortisol receptors.

CONCLUSIONS

This study finds sex-specific associations of C-reactive protein and cortisol levels with prenatal depression in women and with decreased development of newborn P50 inhibition. Sex-based differences in maternal response to depression with inflammation or cortisol and their developmental effects may reflect evolutionary influences to promote survival in adversity. Decreased newborn P50 inhibition is associated with later childhood behavioral problems, and decreased P50 inhibition is a pathophysiological feature of several mental illnesses.

Quantitative meta-analysis of maternal prenatal salivary cortisol and newborn birthweight does not identify effect of fetal sex

BACKGROUND

Heightened concentration of maternal cortisol is a frequently proposed mechanism linking adverse maternal environments with poor birth outcomes, including birth weight. It is commonly hypothesized that prenatal exposures have sexually dimorphic effects on fetal development, however few studies have assessed the effects of fetal sex on the relationship between maternal cortisol and birth outcomes.

METHODS

In a previous systematic review and meta-analysis we obtained data from authors of included studies to calculate trimester-specific correlations between maternal prenatal salivary cortisol and newborn birth weight. Given that this data was well-poised to address the unknown effects of fetal sex on the relationship between maternal cortisol and birth outcomes, we contacted authors a second time with request to unblind sex into the correlations. An updated database search was conducted to identify potentially relevant articles published within 2018 and two additional articles were included.

RESULTS AND DISCUSSION

Eleven studies with a total of 2236 maternal-fetal dyads demonstrated negative correlations for both males, -0.15 (95% CI -0.24 to -0.06, I² = 98.5%, p < 0.001) and females -0.21 (95% CI -0.25 to -0.17, I² = 93.3%, p < 0.001). Sex difference were not statistically significant, p = 0.62. Despite greater exposure to cortisol and lower birth weight among females, the association did not differ by sex.

Beyond the HPA-axis: Exploring maternal prenatal influences on birth outcomes and stress reactivity

Accumulating evidence suggests that antenatal maternal stress is associated with altered behavioral and physiological outcomes in the offspring, however, whether this association is causal and the underlying biological mechanisms remain largely unknown. While the most studied mediator of maternal stress influences on the fetus has generally been cortisol, alternative novel markers of stress or inflammation warrant further consideration. The current investigation explored the influence of variations in self-reported symptoms of distress, stress hormones and inflammatory markers on infant birth outcomes and early stress regulation. The sample consisted of 104 pregnant women (mean gestational age = 34.76; SD = 1.12) and their healthy newborns. Maternal self-reported symptoms of depression and anxiety were evaluated through the Edinburgh Postnatal Depression Scale and the State-Trait Anxiety Inventory and levels of serum Interleukine-6 (IL-6), C-Reactive Protein (CRP), salivary cortisol and alpha amylase (sAA) were measured in late pregnancy. Newborns' cortisol and behavioral response to the heel-stick was assessed 48-72 hours after birth. The associations between maternal stress measures and infant birth outcomes and stress reactivity, adjusted for potential confounders, were examined through hierarchical linear regressions and hierarchical linear models. Higher maternal IL-6 levels were associated with smaller head circumference at birth, while diurnal sAA levels were positively associated with birthweight. Maternal diurnal cortisol was related to newborn's stress reactivity: a flatter infant cortisol response to the heel-stick was associated with greater maternal cortisol increases after awakening during pregnancy, while greater infant behavioural reactivity was related to a flatter maternal diurnal cortisol profile. The observational nature of these data does not allow for causal inferences but the current findings illustrate that antenatal factors related to alterations in maternal stress and immune response systems are associated with fetal growth and neonatal stress reactivity. This may have implications for later health and psychological outcomes.

Does Prenatal Maternal Distress Contribute to Sex Differences in Child Psychopathology?

PURPOSE OF REVIEW

Prenatal maternal psychological distress is an established risk factor for the development of psychopathology in offspring. The purpose of this review is to evaluate whether sex differences in fetal responses to maternal distress contribute to sex differences in subsequent psychopathology.

RECENT FINDINGS

Male and female fetuses respond differently to stress signals. We review recent evidence that demonstrates a sex-specific pattern of association between prenatal maternal distress and pathways associated with risk for psychopathology including offspring hypothalamic pituitary adrenocortical (HPA) axis regulation, brain development, and negative emotionality. Prenatal maternal distress exerts sex-specific consequences on the fetus. These differences may contribute to the well-established sex differences in psychopathology and in particular to greater female vulnerability to develop internalizing problems.

Maternal Lifetime Trauma and Birthweight: Effect Modification by In Utero Cortisol and Child Sex

OBJECTIVES

To evaluate associations between maternal lifetime traumatic stress and offspring birthweight and examine modifying effects of third trimester cortisol and fetal sex.

STUDY DESIGN

Analyses included 314 mother-infant dyads from an ethnically mixed pregnancy cohort. Maternal lifetime trauma was reported via the Life Stressor Checklist-Revised. Fenton birthweight for gestational age z-scores (BWGA-z) were calculated. A 3-cm scalp-nearest maternal hair segment collected at birth was assayed to reflect cumulative third trimester cortisol secretion. Multivariable regression was used to investigate associations between maternal lifetime trauma and BWGA-z and examine 2- and 3-way interactions with cortisol and fetal sex. Because subjects with low or high cortisol levels could represent susceptible populations, varying coefficient models that relax the linearity assumption on cortisol level were used to assess the modification of maternal lifetime trauma associations with BWGA-z as a function of cortisol.

RESULTS

Women were primarily minorities (41% Hispanic, 26% black) with ≤12 years education (63%); 63% reported ≥1 traumatic event. Prenatal cortisol modified the association between maternal lifetime trauma and birthweight. Women with higher lifetime trauma and increased cortisol had significantly lower birthweight infants in males; among males exposed to the 90th percentile of cortisol, a 1-unit increase in trauma score was associated with a 0.19-unit decrease in BWGA-z (95% CI, -0.34 to -0.04). Associations among females were nonsignificant, regardless of cortisol level.

CONCLUSIONS

These findings underscore the need to consider complex interactions among maternal trauma, disrupted in utero cortisol production, and fetal sex to fully elucidate intergenerational effects of maternal lifetime trauma.

Social buffering of the maternal and infant HPA axes: Mediation and moderation in the intergenerational transmission of adverse childhood experiences

Supportive social relationships can reduce both psychological and physiological responses to stressful experiences. Recently, studies have also assessed the potential for social relationships to buffer the intergenerational transmission of stress. The majority of these studies, however, have focussed on social learning as a mechanism responsible for the intergenerational transmission of stress. Evidence of biological mechanisms is lacking. The objective of the current study was, therefore, to determine whether the association between maternal adverse childhood experiences (ACEs) and infant hypothalamic-pituitary-adrenal (HPA) axis function is mediated by maternal HPA axis function during pregnancy and moderated by social support. Data were from 243 mother-infant dyads enrolled in a prospective longitudinal cohort (the Alberta Pregnancy Outcomes and Nutrition Study). Maternal history of ACEs was retrospectively assessed while maternal perceived social support and salivary cortisol were assessed prospectively at 6-22 weeks gestation (Time 1) and 27-37 weeks gestation (Time 2), and infant cortisol reactivity to a laboratory stressor and maternal perceived social support were assessed at 5-10 months postnatal (Time 3). Results revealed that maternal HPA axis function during pregnancy mediated the effects of maternal ACEs on infant HPA axis reactivity, suggesting that the maternal HPA axis is a mechanism by which maternal early life stress is transmitted to offspring. Furthermore, social support in the prenatal and postnatal periods moderated the cascade from maternal ACEs to infant HPA axis reactivity. Specifically, prenatal social support moderated the association between ACEs and maternal HPA axis function during pregnancy, and postnatal social support moderated the association between maternal HPA axis function and infant cortisol reactivity. These findings highlight the social sensitivity of the HPA axis and suggest the utility of social relationships as an intervention target to reduce the effects of maternal early life stress on infant outcomes.

Prenatal stress and the development of psychopathology: Lifestyle behaviors as a fundamental part of the puzzle

Maternal psychological stress, depression, and anxiety during pregnancy (prenatal stress; PNS) are thought to impact fetal development with long-term effects on offspring outcome. These effects would include physical and mental health, including psychopathology. Maternal sleep, diet, and exercise during pregnancy are lifestyle behaviors that are understudied and often solely included in PNS studies as confounders. However, there are indications that these lifestyle behaviors may actually constitute essential mediators between PNS and fetal programming processes. The goal of this theoretical review was to investigate this idea by looking at the evidence for associations between PNS and sleep, diet, and exercise, and by piecing together the information on potential underlying mechanisms and causal pathways through which these factors may affect the offspring. The analysis of the literature led to the conclusion that sleep, diet, and exercise during pregnancy, may have fundamental roles as mediators between PNS and maternal pregnancy physiology. By integrating these lifestyle behaviors into models of prenatal programming of development, a qualitatively higher and more comprehensive understanding of the prenatal origins of psychopathology can be obtained. The review finalizes by discussing some of the present challenges facing the field of PNS and offspring programming, and offering solutions for future research.

Sex Differences in Vulnerability to Prenatal Stress: a Review of the Recent Literature

PURPOSE OF REVIEW

To evaluate the degree to which recent studies provide evidence that the effects of prenatal maternal stress (PNMS) on child health outcomes vary depending on the child's biological sex. In this review, we used a broad definition of stress, including negative life events, psychological stress, and established stress biomarkers. We identified 50 peer-reviewed articles (published January 2015-December 2017) meeting the inclusion criteria.

RECENT FINDINGS

Most articles (k = 35) found evidence of either sex-specific associations (significant in one sex but not the other) or significant PNMSxstress interactions for at least one child health outcome. Evidence for sex-dependent effects was strongest in the group of studies evaluating child neural/nervous system development and temperament as outcomes. There is sufficient evidence of sex-dependent associations to recommend that researchers always consider the potential role of child sex in PNMS programming studies and report descriptive statistics for study outcomes stratified by child biological sex.

The effect of gestational period on the association between maternal prenatal salivary cortisol and birth weight: A systematic review and meta-analysis

BACKGROUND

Studies exploring the relations between maternal stress and fetal development show an association between increased maternal stress and adverse birth outcomes. A frequently proposed mechanism linking maternal prenatal stress and adverse birth outcomes is heightened concentrations of maternal cortisol. To date, studies exploring this association have reported conflicting results because of the diverse approaches taken to measuring cortisol and the wide variety of possible birth outcomes explored. To add clarity to the growing body of literature, this systematic review and meta-analysis reports empirical findings on the association between maternal prenatal salivary cortisol and newborn birth weight.

METHODS

Searches for relevant papers published up until November 2017 were run in MEDLINE, EMBASE, PsycINFO, and CINAHL. Non-English language papers were included and experts were contacted when necessary. We included data from human observational studies that were designed or had an underlying intention to measure maternal prenatal salivary cortisol and newborn birth weight. We only included data from measurements of salivary cortisol to prevent rendering of the review unsuitable for meta-analysis. Two independent reviewers assessed study eligibility and quality. For every maternal-fetal dyad, an area under the curve with respect to ground (AUCg) of maternal cortisol was calculated to determine a Pearson's correlation coefficient with a continuous measure of newborn birth weight. Correlation coefficients were then pooled across all stages of gestation. To examine if there are critical gestational periods in which the fetus may be more susceptible to elevated concentration of maternal salivary cortisol, a meta-analysis was performed on separate correlations calculated from gestational trimesters.

RESULTS

Nine studies with a total of 1606 maternal-fetal dyads demonstrated a negative correlation between pooled maternal salivary cortisol and birth weight (-0.24, 95% CI -0.28 to -0.20), but there was a high degree of heterogeneity between studies (I² = 88.9%). To investigate heterogeneity, subgroup analysis by trimester of the pooled correlation between salivary cortisol and birth weight was performed with the following correlations found: first trimester, -0.18 (95% CI -0.32 to -0.03, I² = 97.3%); second trimester, -0.20 (95% CI -0.28 to -0.12, I² = 98.3%); and third trimester, -0.30 (95% CI -0.33 to -0.26, I² = 85.4%).

DISCUSSION

A consistently negative association was observed between maternal cortisol and infant birth weight. The review highlights specific gaps in the literature on the relationship between maternal prenatal salivary cortisol and newborn birth weight. Although a significant negative correlation was found, substantial heterogeneity of effects and the likelihood of publication bias exist. The third trimester was revealed as a possible critical gestational period for heightened maternal cortisol concentration to affect birth weight. Challenges faced in this body of research and recommendations for future research are discussed.

Like mother, like daughter: heritability of female Richardson's ground squirrel Urocitellus richardsonii cortisol stress responses

Activation of the hypothalamic-pituitary-adrenal (HPA) axis liberates glucocorticoids, which provides an acute indication of an individual's response to stressors. The heritability of the stress response in wild mammals, however, remains poorly documented. We quantified the cortisol stress response of female Richardson's ground squirrels (RGSs) to handling and physical restraint, testing for: (1) the effects of individual age, time of day, and sample latency; (2) repeatability within individuals; (3) narrow-sense heritability; and (4) differences among individuals owing to potential genetic and/or environmental effects. We detected a positive linear relationship between baseline plasma cortisol (BL-cortisol) concentration and stress-induced plasma cortisol (SI-cortisol) concentration that defined each individual's cortisol stress response. BL-cortisol, SI-cortisol, and stress response did not differ according to the time the sample was taken, or by subject age. Cortisol stress response was highly repeatable within individuals, had a mother-offspring heritability of h 2 = 0.40 ± 0.24 (mean ± SE), full-sibling heritability ofh FS 2   =   0.37   ±   0.71 , and half-sibling heritability ofh HS 2 =   0.75   ±   1.41 . Stress responses of sibling groups, immediate-family groups, and squirrels within a given area did not differ, whereas those of individuals from more distantly related matrilines did. Our results highlight the natural variability in HPA axis reactivity among individuals by quantifying both BL- and SI-cortisol levels, demonstrate partial heritability of the stress response that is not attributable to environmental variation, and suggest that at least part of an individual's stress response can be accounted for by differences in matrilineal history.

Fetal sex is associated with maternal stimulated cytokine production, but not serum cytokine levels, in human pregnancy

Some studies suggest that fetal sex plays a role in maternal physiological processes during pregnancy including glycemic control, blood pressure, and cortisol regulation. However, data examining fetal sex-specific differences in maternal immune parameters is lacking. In the current study, serum levels of interleukin(IL)-6, IL-8, and tumor necrosis factor(TNF)-α as well as LPS-stimulated production of IL-6, IL-8, TNF-α, and IL-1β by PBMCs incubated for 24h were assessed in early, mid, and late pregnancy among 80 women (46 with male and 34 with female fetuses). Linear mixed models showed that women carrying females versus males exhibited greater stimulated production of IL-6 at each timepoint (ps⩽0.03), TNF-α in early pregnancy (p=0.04), and IL-1β in mid- and late pregnancy (ps⩽0.05). Despite changes in serum levels of IL-8 (p=0.002) and TNF-α (p<0.0001) across pregnancy, no differences in any serum cytokines were observed in relation to fetal sex (ps>0.85). In conclusion, in pregnant women, those carrying female versus male fetuses exhibited greater stimulated cytokine production across pregnancy. Differential inflammatory responses could affect maternal health and fetal development. Fetal sex should be considered as a factor in studies of maternal inflammation. These findings have relevance both clinically and conceptually. For example, maternal asthma is exacerbated among women carrying female versus male fetuses. In addition, data on associations between fetal sex and maternal immune function among women with health conditions (e.g., preeclampsia) and adverse pregnancy outcomes (e.g., preterm birth) would be informative.

Full-term deliveries without antecedent labor reveal sex differences in umbilical cord glucocorticoid concentrations

BACKGROUND

Previous studies have shown that pregnant women have higher salivary cortisol levels when the fetus is female. These findings suggest a basis for the sex differences observed in many offspring outcomes after exposure to in utero stress, but it is not known if fetal adrenal glucocorticoid synthesis differs by sex.

METHODS

Arterial and venous umbilical cord blood samples were collected immediately after scheduled cesarean delivery (n=52, 25 female). Cortisol and corticosterone concentrations were quantified by liquid chromatography coupled to tandem mass spectrometry.

RESULTS

Sex differences were observed for fetal arterial and venous cortisol and venous corticosterone, with higher levels present when the fetus was female. However, sex differences were not observed for fetal synthesis of cortisol, suggesting that the fetus does not control the differences observed in cord blood glucocorticoids.

CONCLUSIONS

The presence of sex differences in umbilical cord glucocorticoid concentrations in the absence of sex differences in glucocorticoid synthesis by the fetal adrenal gland suggests that these differences have a maternal or placental origin. Thus, the in utero glucocorticoids in circulation are sex-specific and may have developmental importance for sex differences in psychiatric and neurodevelopment disorders that display sex biases.

Urinary bisphenol A is associated with dysregulation of HPA-axis function in pregnant women: Findings from the APrON cohort study

BACKGROUND

Bisphenol A (BPA) is associated with dysregulation of hypothalamic-pituitary-adrenal (HPA) axis activity in rodents, but evidence in humans is lacking.

OBJECTIVE

To determine whether BPA exposure during pregnancy is associated with dysregulation of the HPA-axis, we examined the association between urinary BPA concentrations and diurnal salivary cortisol in pregnant women. Secondary analyses investigated whether the association between BPA and cortisol was dependent on fetal sex.

METHODS

Diurnal salivary cortisol and urinary BPA were collected during pregnancy from 174 women in a longitudinal cohort study, the Alberta Pregnancy Outcomes and Nutrition (APrON) study. Associations between BPA and daytime cortisol and the cortisol awakening response (CAR) were estimated using mixed models after adjusting for covariates.

RESULTS

Higher concentrations of total BPA uncorrected for urinary creatinine were associated with dysregulation of the daytime cortisol pattern, including reduced cortisol at waking, β=-.055, 95% CI (-.100, -.010) and a flatter daytime pattern, β=.014, 95% CI (.006, .022) and β=-.0007 95% CI (-.001, -.0002) for the linear and quadratic slopes, respectively. Effect sizes in creatinine corrected BPA models were slightly smaller. None of the interactions between fetal sex and BPA were significant (all 95% CI's include zero).

CONCLUSIONS

These findings provide the first human evidence suggesting that BPA exposure is associated with dysregulation of HPA-axis function during pregnancy.

Sexually dimorphic and interactive effects of prenatal maternal cortisol and psychological distress on infant cortisol reactivity

In utero exposure to maternal psychological distress is a risk factor for developmental psychopathology, and these effects are believed to partially occur via dysregulation of the maternal and fetal hypothalamus-adrenal-pituitary axes. Nevertheless, only a few human studies have directly assessed the effects of prenatal cortisol exposure on infant cortisol reactivity, and none have investigated sex differences or potential interactions between prenatal cortisol and psychological distress. Here we report on a prospective longitudinal investigation (N = 236) of in utero exposure to maternal cortisol and distress in a relatively high socioeconomic status and low-risk population to determine whether these exposures interact in their effects on infant (M age = 3.0 months, range = 2.3-5.0 months, 51.9% male) cortisol reactivity and whether there are sex differences in these effects. Results revealed both sexually dimorphic and interactive effects of prenatal cortisol and distress, even after controlling for postnatal distress. In general, blunted reactivity in females was associated with exposure to high maternal distress and flattened patterns of diurnal maternal cortisol, whereas blunted reactivity in males was associated with exposure to steeper morning increases and daytime decreases in maternal cortisol. The findings suggest that sex differences in the effects of prenatal cortisol and distress on infant cortisol reactivity are a plausible mechanism by which maternal experiences during pregnancy contribute to sex differences in the development of psychopathology.

Sex-dependent effects of lead and prenatal stress on post-translational histone modifications in frontal cortex and hippocampus in the early postnatal brain

Environmental lead (Pb) exposure and prenatal stress (PS) are co-occurring risk factors for impaired cognition and other disorders/diseases in adulthood and target common biological substrates in the brain. Sex-dependent differences characterize the neurochemical and behavioral responses of the brain to Pb and PS and sexually dimorphic histone modifications have been reported to occur in at-risk brain regions (cortex and hippocampus) during development. The present study sought to examine levels and developmental timing of sexually dimorphic histone modifications (i.e., H3K9/14Ac and H3K9Me3) and the extent to which they may be altered by Pb±PS. Female C57/Bl6 mice were randomly assigned to receive distilled deionized drinking water containing 0 or 100ppm Pb acetate for 2 months prior to breeding and throughout lactation. Half of the dams in each group were exposed to restraint stress (PS, three restraint sessions in plastic cylindrical devices 3×/day at for 30min/day (1000, 1300, and 1600h)) from gestational day 11-19 or no stress (NS). At delivery (PND0) and postnatal day 6 (PND6), pups were euthanized and frontal cortex and hippocampus were removed, homogenized, and assayed for levels of H3K9/14Ac and H3K9Me3. Sex-dependent differences in both levels of histone modifications as well as the developmental trajectory of changes in these levels were observed in both structures and these parameters were differentially affected by Pb±PS in a sex and brain-region-dependent manner. Disruptions of these epigenetic processes by developmental Pb±PS may underlie some of the sex-dependent neurobehavioral differences previously observed in these animals.

The gestational foundation of sex differences in development and vulnerability

Despite long-standing interest in the role of sex on human development, the functional consequences of fetal sex on early development are not well-understood. Here we explore the gestational origins of sex as a moderator of development. In accordance with the focus of this special issue, we examine evidence for a sex differential in vulnerability to prenatal and perinatal risks. Exposures evaluated include those present in the external environment (e.g., lead, pesticides), those introduced by maternal behaviors (e.g., alcohol, opioid use), and those resulting from an adverse intrauterine environment (e.g., preterm birth). We also provide current knowledge on the degree to which sex differences in fetal neurobehavioral development (i.e., cardiac and motor patterns) are present prior to birth. Also considered are contemporaneous and persistent sex of fetus effects on the pregnant woman. Converging evidence confirms that infant and early childhood developmental outcomes of male fetuses exposed to prenatal and perinatal adversities are more highly impaired than those of female fetuses. In certain circumstances, male fetuses are both more frequently exposed to early adversities and more affected by them when exposed than are female fetuses. The mechanisms through which biological sex imparts vulnerability or protection on the developing nervous system are largely unknown. We consider models that implicate variation in maturation, placental functioning, and the neuroendocrine milieu as potential contributors. Many studies use sex as a control variable, some analyze and report main effects for sex, but those that report interaction terms for sex are scarce. As a result, the true scope of sex differences in vulnerability is unknown.