A global multicohort study to map subcortical brain development and cognition in infancy and early childhood.

The human brain grows quickly during infancy and early childhood, but factors influencing brain maturation in this period remain poorly understood. To address this gap, we harmonized data from eight diverse cohorts, creating one of the largest pediatric neuroimaging datasets to date focused on birth to 6 years of age. We mapped the developmental trajectory of intracranial and subcortical volumes in ∼2,000 children and studied how sociodemographic factors and adverse birth outcomes influence brain structure and cognition. The amygdala was the first subcortical volume to mature, whereas the thalamus exhibited protracted development. Males had larger brain volumes than females, and children born preterm or with low birthweight showed catch-up growth with age. Socioeconomic factors exerted region- and time-specific effects. Regarding cognition, males scored lower than females; preterm birth affected all developmental areas tested, and socioeconomic factors affected visual reception and receptive language. Brain-cognition correlations revealed region-specific associations.

Social determinants of health and obstetric outcomes: A report and recommendations of the workshop of the Society for Maternal-Fetal Medicine.

This article is a report of a 2-day workshop, entitled "Social determinants of health and obstetric outcomes," held during the Society for Maternal-Fetal Medicine 2022 Annual Pregnancy Meeting. Participants' fields of expertise included obstetrics, pediatrics, epidemiology, health services, health equity, community-based research, and systems biology. The Commonwealth Foundation and the Alliance of Innovation on Maternal Health cosponsored the workshop and the Society for Women's Health Research provided additional support. The workshop included presentations and small group discussions, and its goals were to accomplish the following.

Greater male variability in daily energy expenditure develops through puberty.

There is considerably greater variation in metabolic rates between men than between women, in terms of basal, activity and total (daily) energy expenditure (EE). One possible explanation is that EE is associated with male sexual characteristics (which are known to vary more than other traits) such as musculature and athletic capacity. Such traits might be predicted to be most prominent during periods of adolescence and young adulthood, when sexual behaviour develops and peaks. We tested this hypothesis on a large dataset by comparing the amount of male variation and female variation in total EE, activity EE and basal EE, at different life stages, along with several morphological traits: height, fat free mass and fat mass. Total EE, and to some degree also activity EE, exhibit considerable greater male variation (GMV) in young adults, and then a decreasing GMV in progressively older individuals. Arguably, basal EE, and also morphometrics, do not exhibit this pattern. These findings suggest that single male sexual characteristics may not exhibit peak GMV in young adulthood, however total and perhaps also activity EE, associated with many morphological and physiological traits combined, do exhibit GMV most prominently during the reproductive life stages.

Total daily energy expenditure has declined over the past three decades due to declining basal expenditure, not reduced activity expenditure.

Obesity is caused by a prolonged positive energy balance1,2. Whether reduced energy expenditure stemming from reduced activity levels contributes is debated3,4. Here we show that in both sexes, total energy expenditure (TEE) adjusted for body composition and age declined since the late 1980s, while adjusted activity energy expenditure increased over time. We use the International Atomic Energy Agency Doubly Labelled Water database on energy expenditure of adults in the United States and Europe (n = 4,799) to explore patterns in total (TEE: n = 4,799), basal (BEE: n = 1,432) and physical activity energy expenditure (n = 1,432) over time. In males, adjusted BEE decreased significantly, but in females this did not reach significance. A larger dataset of basal metabolic rate (equivalent to BEE) measurements of 9,912 adults across 163 studies spanning 100 years replicates the decline in BEE in both sexes. We conclude that increasing obesity in the United States/Europe has probably not been fuelled by reduced physical activity leading to lowered TEE. We identify here a decline in adjusted BEE as a previously unrecognized factor.

The association between history of prenatal loss and maternal psychological state in a subsequent pregnancy: an ecological momentary assessment (EMA) study.

BACKGROUND: Prenatal loss which occurs in approximately 20% of pregnancies represents a well-established risk factor for anxiety and affective disorders. In the current study, we examined whether a history of prenatal loss is associated with a subsequent pregnancy with maternal psychological state using ecological momentary assessment (EMA)-based measures of pregnancy-specific distress and mood in everyday life. METHOD: This study was conducted in a cohort of N = 155 healthy pregnant women, of which N = 40 had a history of prenatal loss. An EMA protocol was used in early and late pregnancy to collect repeated measures of maternal stress and mood, on average eight times per day over a consecutive 4-day period. The association between a history of prenatal loss and psychological state was estimated using linear mixed models. RESULTS: Compared to women who had not experienced a prior prenatal loss, women with a history of prenatal loss reported higher levels of pregnancy-specific distress in early as well as late pregnancy and also were more nervous and tired. Furthermore, in the comparison group pregnancy-specific distress decreased and mood improved from early to late pregnancy, whereas these changes across pregnancy were not evident in women in the prenatal loss group. CONCLUSION: Our findings suggest that prenatal loss in a prior pregnancy is associated with a subsequent pregnancy with significantly higher stress and impaired mood levels in everyday life across gestation. These findings have important implications for designing EMA-based ambulatory, personalized interventions to reduce stress during pregnancy in this high-risk group.

Variability in energy expenditure is much greater in males than females.

In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction.

Diurnal cortisol variation during pregnancy in Turkish origin and non-migrant women in a German birth cohort study.

BACKGROUND: Immigrants from Turkey experience health disadvantages relative to non-immigrant populations in Germany that are manifest from the earliest stages of the lifespan onwards and are perpetuated across generations. Chronic stress and perturbations of stress-responsive physiological systems, including the hypothalamus-pituitary-adrenal (HPA)-axis, are believed to in part mediate this relationship. Cortisol plays an important role in the association between maternal stress during pregnancy and many pregnancy-, birth- and offspring-related outcomes. We therefore examined whether maternal migrant background is associated with diurnal cortisol variation during pregnancy. METHODS: 109 pregnant women (incl. n = 32 Turkish origin women) that participated in a multi-site prospective cohort study in Germany collected saliva samples across the day on two consecutive days around 24 and 32 weeks gestation. Hierarchical linear models were applied to quantify associations between migrant background and diurnal cortisol variation across pregnancy. RESULTS: Women of Turkish origin exhibited a significantly lower cortisol awakening response (CAR) and a flatter diurnal cortisol slope (DCS) compared to non-migrant women after adjusting for household income. These relationships between migrant status and diurnal cortisol variation were mainly driven by 2nd generation migrants. DISCUSSION: A potential HPA axis dysregulation of Turkish-origin pregnant women may contribute to the intergenerational transmission of health disadvantages in this group.

Total energy expenditure is repeatable in adults but not associated with short-term changes in body composition.

Low total energy expenditure (TEE, MJ/d) has been a hypothesized risk factor for weight gain, but repeatability of TEE, a critical variable in longitudinal studies of energy balance, is understudied. We examine repeated doubly labeled water (DLW) measurements of TEE in 348 adults and 47 children from the IAEA DLW Database (mean ± SD time interval: 1.9 ± 2.9 y) to assess repeatability of TEE, and to examine if TEE adjusted for age, sex, fat-free mass, and fat mass is associated with changes in weight or body composition. Here, we report that repeatability of TEE is high for adults, but not children. Bivariate Bayesian mixed models show no among or within-individual correlation between body composition (fat mass or percentage) and unadjusted TEE in adults. For adults aged 20-60 y (N = 267; time interval: 7.4 ± 12.2 weeks), increases in adjusted TEE are associated with weight gain but not with changes in body composition; results are similar for subjects with intervals >4 weeks (N = 53; 29.1 ± 12.8 weeks). This suggests low TEE is not a risk factor for, and high TEE is not protective against, weight or body fat gain over the time intervals tested.

Daily energy expenditure through the human life course.

Total daily energy expenditure ("total expenditure") reflects daily energy needs and is a critical variable in human health and physiology, but its trajectory over the life course is poorly studied. We analyzed a large, diverse database of total expenditure measured by the doubly labeled water method for males and females aged 8 days to 95 years. Total expenditure increased with fat-free mass in a power-law manner, with four distinct life stages. Fat-free mass-adjusted expenditure accelerates rapidly in neonates to ~50% above adult values at ~1 year; declines slowly to adult levels by ~20 years; remains stable in adulthood (20 to 60 years), even during pregnancy; then declines in older adults. These changes shed light on human development and aging and should help shape nutrition and health strategies across the life span.

Racial differences across pregnancy in maternal pro-inflammatory immune responsivity and its regulation by glucocorticoids.

BACKGROUND: The distribution of adverse pregnancy, birth and subsequent child developmental and health outcomes in the U.S. is characterized by pronounced racial (particularly Black-white) disparities. In this context, chronic stress exposure represents a variable of considerable importance, and the immune/inflammatory system represents a leading candidate biological pathway of interest. Previous pregnancy studies examining racial disparities in immune processes have largely utilized circulating cytokine levels, and have yielded null or mixed results. Circulating cytokines primarily represent basal secretion and do not necessarily represent functional features of immune responsivity and regulation. Thus, in order to conduct a more in-depth characterization of racial differences in functional immune properties during pregnancy, we utilized an ex vivo stimulation assay, a dynamic measure of immune function at the cellular level, to investigate Black-white racial differences in in mid- and late-gestation in i) pro-inflammatory (IL-6) responsivity of leukocytes to antigen [lipopolysaccharide (LPS)] challenge, and ii) regulation (dampening) of this pro-inflammatory response by glucocorticoids. METHOD: 177 women (N = 42 Black (24%), n = 135 white (76%)) with a singleton, intrauterine pregnancy provided 20 mL venous blood in mid- (16.6 ± 2.4 wks) and late (33.3 ± 1.1 wks) pregnancy. Maternal pro-inflammatory responsivity of leukocytes was quantified by assessing the release of the pro-inflammatory cytokine IL-6 in response to LPS stimulation, and regulation of the pro-inflammatory response was quantified by assessing the suppression of the stimulated IL-6 response after co-incubation with progressively increasing levels of dexamethasone [10-7, 10-6, 10-5 M] (i.e., glucocorticoid receptor resistance (GRR)). A priori model covariates included maternal age, parity, SES (socioeconomic status), and pre-pregnancy BMI. RESULTS: Maternal pro-inflammatory responsivity (LPS-stimulated IL-6) and GRR increased significantly across mid- and late gestation (adjusted ß = 0.157, p = 0.007; ß = 0.627, p < 0.001, respectively). Across both time points in pregnancy Black women exhibited significantly higher LPS-stimulated IL-6 release and reduced glucocorticoid regulation of the IL-6 response (i.e., higher GRR) relative to white women, before and after adjusting for covariates (ß = 0.381, p = 0.0030; ß = 0.391, p = 0.0075, respectively). There was no racial difference in the concentrations of circulating IL-6 (p = 0.9199). CONCLUSION: Our findings support the hypothesis postulating significant racial (Black-white) differences in key functional properties of the maternal immune system in pregnancy, which were not apparent using circulating cytokine measures. These data elucidate a potentially important physiological mechanism underlying the transduction of environmental conditions into racial disparities in reproductive and subsequent child health outcomes, and the use of these ex vivo measures should be considered in future studies.

Association of maternal migrant background with inflammation during pregnancy - Results of a birth cohort study in Germany.

BACKGROUND: Health disparities in children of immigrants are prevalent from birth and are hypothesized to - in part - emerge as a biological consequence of migration's unfavorable social and psychological sequelae. The aim of this study was to examine whether maternal migrant background is associated with inflammation during pregnancy - a key pathway by which maternal states and conditions during pregnancy may influence fetal development and subsequent pregnancy, birth, and child developmental and health outcomes. MATERIAL AND METHODS: Data was available from 126 pregnant women who participated in a population based multi-site prospective birth cohort study in Bielefeld and Berlin, Germany. The study included two study visits in mid- and late pregnancy. At each visit, a composite maternal pro-inflammatory score was derived from circulating levels of plasma inflammatory markers (IL-6, CRP). Migrant background was defined by country of origin of participants and their parents' (Turkey or other) and generation status (1st or 2nd generation). We applied hierarchical linear models (HLM) in order to quantify the relationship between different migrant background variables and inflammation during pregnancy after adjustment for potential confounders (including socioeconomic status). RESULTS: Migrant background was significantly associated with inflammation during pregnancy. When compared to women without migrant background, levels of inflammation were increased in 1) pregnant women with migrant background in general (B = 0.35, SE = 0.12, p < .01); 2) 1st (B = 0.28, SE = 0.15, p < .10) and 2nd generation (B = 0.40, SE = 0.15, p < .01); 3) women with a Turkish migrant background (B = 0.28, SE = 0.14, p < .10) and women with another migrant background (B = 0.42, SE = 0.15, p < .01); and 4) 2nd generation Turkish origin women (B = 0.38, SE = 0.20, p < .10), 1st generation women with other migrant background (B = 0.44, SE = 0.26, p < .10), and 2nd generation women with other migrant background (B = 0.43, SE = 0.17, p < .05). DISCUSSION: Our findings support a role for maternal inflammation as a pathway of intergenerational transmission of migration-related health inequalities, suggest that the effect seems to persist in 2nd generation immigrants, and highlight the need for future research and targeted interventions in this context.

Psychological stress and cortisol during pregnancy: An ecological momentary assessment (EMA)-Based within- and between-person analysis.

BACKGROUND: Although the linkage between psychological stress and cortisol is believed to mediate the association of stress with health outcomes, several studies have been unable to demonstrate this association. We suggest this inability may be a consequence of limitations in the measurement approach and/or reliance on analytic strategies that focus on associations across, rather than within individuals. The link between psychological stress and cortisol is of particular interest in the context of pregnancy and fetal development. Using an ecological momentary assessment (EMA) design, we examined the association between psychological stress and cortisol at the between- and the within-person level. METHODS: 152 participants completed a 4-day long EMA protocol serially in early, mid and late pregnancy to provide momentary stress appraisals (average of 150 measures/subject) and saliva samples (average of 55 samples/subject) for quantification of cortisol. The association between stress and cortisol was estimated using linear mixed models. RESULTS: After accounting for the effects of key determinants of variation in cortisol, momentary stress was significantly and positively associated with cortisol at the within-person level (B = .030, p = .031), but not at the between-person level. No association was evident for traditional retrospective measures of stress with cortisol at either the between- or the within-person level. CONCLUSIONS: Our study highlights the value of EMA methods and linear mixed-modeling approaches in linking maternal psychological and physiological states across pregnancy. These findings may have important implications for the development of personalized risk identification and "just-in-time" intervention strategies to optimize maternal and child health.

Maternal subjective social standing is related to inflammation during pregnancy.

BACKGROUND: The association of socioeconomic status (SES) with health and disease risk is well established. Low-grade inflammation represents a key pathway believed to underlie this association. Previous research has suggested that subjective social standing (SSS) is more consistently associated with health outcomes than objective measures of SES such as income and education. Given the importance of maternal inflammatory state in a wide array of pregnancy, birth and fetal/child developmental and health outcomes, we examine here the independent association of maternal SSS relative to objective SES with pro-inflammatory state during pregnancy. METHODS: We conducted a longitudinal study of an ethnically diverse sample of 250 pregnant women with 3 study visits in early, mid and late gestation. We obtained objective measures of SES (income, education), and SSS with reference to the community and to the nation using the MacArthur Scale of Subjective Social Status. At each study visit, a composite maternal pro-inflammatory score was derived from circulating levels of inflammatory markers (IL-6, CRP, TNF-α). RESULTS: In hierarchical linear models, SSS but not objective SES was significantly and negatively associated with maternal inflammatory state. Moreover, the relationship between SSS and inflammatory state remained significant after accounting for objective SES. SSS with reference to the community was a stronger predictor of inflammatory state than SSS with reference to the nation. DISCUSSION: Our finding adds to the scientific literature on SSS and health, highlights the importance of including SSS measures in this context, and supports future research on the relative role and biological pathways by which SSS may impact pregnancy, birth and fetal/child development and health.

Intergenerational transmission of health disparities among Turkish-origin immigrants in Germany: study protocol of a multi-centric cohort study (BaBi-stress and BaBeK study).

BACKGROUND: Immigrants in Germany exhibit higher levels of social disadvantage when compared to the non-immigrated population. Turkish-origin immigrants constitute an important immigrant group in Germany and show disparities in some health domains that are evident from birth onwards. Several studies have shown the mechanisms by which social disadvantage is biologically embedded to affect health over the lifespan. Relatively little, however, is still known about if and how the maternal social situation is transmitted to the next generation. This study therefore aims to analyse the effects of maternal socioeconomic status and migration status on stress-related maternal-placental-fetal (MPF) biological processes during pregnancy on infant birth and health outcomes. METHODS: This longitudinal cohort study of N = 144 child-mother dyads is located at two study sites in Germany and includes pregnant women of Turkish origin living in Germany as well as pregnant German women. During pregnancy, MPF stress biology markers from maternal blood and saliva samples, maternal socio-economic and migration-related information, medical risk variables and psychological well-being are assessed. After birth, infant anthropometric measures and developmental outcomes are assessed. The same measures will be assessed in and compared to Turkish pregnant women based on a collaboration with BABIP study in Istanbul. DISCUSSION: This is the first study on intergenerational transmission of health disparities in Germany with a focus on women of Turkish-origin. The study faces similar risks of bias as other birth cohorts do. The study has implemented various measures, e.g. culturally sensitive recruitment strategies, attempt to recruit and follow-up as many pregnant women as possible independent of their social or cultural background. Nevertheless, the response rate among lower-educated families is lower. The possibility to compare results with a cohort from Turkey is a strength of this study. However, starting at different times and with slightly different recruitment strategies and designs may result in cohort effects and may affect comparability of the sub-cohorts. TRIAL REGISTRATION: N.A. (Observational study, no clinical trial, no interventions on human participants).

The German Version of the Multidimensional Acculturative Stress Inventory (MASI) for Turkish-Origin Immigrants -Measurement Invariance of Filter Questions and Validation.

The Multidimensional Acculturative Stress Inventory (MASI) is an established measure of acculturative stress for people of Mexican origin living in the United States that has been associated with mental health outcomes in this population. We translated the MASI into German and adapted it for use with Turkish-origin immigrants in Germany. The MASI includes filter questions asking if a potentially stressful event had actually occurred before reporting the stress appraisal of these situations. Measurement invariance testing has become a standard practice to evaluate questionnaire translations, however, measurement invariance of filter questions has been scarcely studied. In Study I, we evaluated measurement invariance of the filter questions between a German-based Turkish sample (N = 233) and the Mexican-origin sample from the original study (N = 174) and could show partial strong factorial invariance for three of the four factors. In Study II, a validation study, relations between the German MASI scores and measures of acculturation and stress indicated discriminant validity. This study contributes to research on measurement invariance of filter questions, thereby providing a measure of acculturative stress that can be used in future research to understand the etiology of health disparities in Turkish-origin immigrants in Germany.

Acculturation and interleukin (IL)-6 concentrations across pregnancy among Mexican-American women.

BACKGROUND: The process of acculturation (post-migration acquisition of host culture and/or loss of heritage culture) likely represents a key mediator of the observed post-migration decline in health that is evident among immigrant populations such as Mexican Americans. The observations that migrant health declines progressively as not only a function of length of stay in the U.S. but also across generations, and that this inter-generational decline in health is evident as early as at the time of birth itself, supports the concept of fetal programming of acculturation's effects. However, the underlying mechanisms remain to be elucidated. Inflammation during pregnancy represents a candidate pathway of particular interest for 2 reasons: it represents a key biological mediator of the psychosocial and/or behavioral sequelae of acculturation on health, and it represents a key pathway by which maternal states and conditions during pregnancy may influence fetal development and subsequent birth and child developmental and health outcomes. Therefore, the aim of this study was to examine the relationship between acculturation and inflammation across pregnancy in a population of Mexican-American women. Specifically, we tested the hypothesis that a higher level of acculturation is associated with higher circulating concentrations across pregnancy of the pro-inflammatory cytokine interleukin-6 (IL-6). METHODS: 75 pregnant first- or second-generation Mexican-American women constituted the study population. Acculturation was quantified using a commonly-used and previously validated measure - the Acculturation Rating Scale for Mexican Americans (ARSMA). Maternal blood samples were collected during early, mid and late pregnancy for analysis of circulating IL-6 concentrations. RESULTS: Hierarchical linear models indicated a significantly and positive main effect of acculturation on IL-6 concentrations across pregnancy after adjusting for key covariates including gestational age(s) at blood sampling, socioeconomic status, pre-pregnancy BMI, and presence of obstetric risk conditions. CONCLUSIONS: Maternal inflammation during pregnancy may represent a biological pathway of interest in the context of the inter-generational effects of acculturation from a mother to her as-yet-unborn child.

Effects of Antenatal Maternal Depressive Symptoms and Socio-Economic Status on Neonatal Brain Development are Modulated by Genetic Risk.

This study included 168 and 85 mother-infant dyads from Asian and United States of America cohorts to examine whether a genomic profile risk score for major depressive disorder (GPRSMDD) moderates the association between antenatal maternal depressive symptoms (or socio-economic status, SES) and fetal neurodevelopment, and to identify candidate biological processes underlying such association. Both cohorts showed a significant interaction between antenatal maternal depressive symptoms and infant GPRSMDD on the right amygdala volume. The Asian cohort also showed such interaction on the right hippocampal volume and shape, thickness of the orbitofrontal and ventromedial prefrontal cortex. Likewise, a significant interaction between SES and infant GPRSMDD was on the right amygdala and hippocampal volumes and shapes. After controlling for each other, the interaction effect of antenatal maternal depressive symptoms and GPRSMDD was mainly shown on the right amygdala, while the interaction effect of SES and GPRSMDD was mainly shown on the right hippocampus. Bioinformatic analyses suggested neurotransmitter/neurotrophic signaling, SNAp REceptor complex, and glutamate receptor activity as common biological processes underlying the influence of antenatal maternal depressive symptoms on fetal cortico-limbic development. These findings suggest gene-environment interdependence in the fetal development of brain regions implicated in cognitive-emotional function. Candidate biological mechanisms involve a range of brain region-specific signaling pathways that converge on common processes of synaptic development.

Intergenerational transmission of the effects of acculturation on health in Hispanic Americans: a fetal programming perspective.

We propose a transdisciplinary, life span framework for examining the underlying cause of the observed intergenerational decline in health among Hispanic Americans. We focus on acculturation, and we posit that acculturation-related processes in first-generation Hispanic immigrant mothers may affect the intrauterine development of an unborn child, via the process of fetal programming, to produce phenotypic effects that may alter the susceptibility for noncommunicable chronic diseases. In this manner, an intergenerational cascade of perpetuation may become established. Our framework may shed light on the biological, behavioral, and social causes of intergenerational cycles of vulnerability among immigrant minority groups, with public health and policy implications for primary prevention and intervention.

Ecological momentary assessment of maternal cortisol profiles over a multiple-day period predicts the length of human gestation.

OBJECTIVE: Biobehavioral models of prenatal stress highlight the importance of the stress-related hormone cortisol. However, the association between maternal cortisol levels and the length of human gestation requires further investigation because most previous studies have relied on one-time cortisol measures assessed at varying gestational ages. This study assessed whether ecological momentary assessment (EMA) of cortisol sampling improves the ability to predict the length of human gestation. In addition, associations between EMA-based measures of psychological state (negative affect) with cortisol levels during pregnancy were assessed. METHODS: For a 4-day period, 25 healthy pregnant women (mean gestational age at assessment = 23.4 [standard deviation = 9.1] weeks) collected seven salivary samples per day for the assessment of cortisol and provided a rating of negative affect every waking hour using an electronic diary. RESULTS: Higher salivary cortisol concentrations at awakening and throughout the day (p = .001), as well as a flatter cortisol response to awakening (p = .005), were associated with shorter length of gestation. Women who delivered an infant at 36 weeks of gestations had 13% higher salivary cortisol levels at awakening than women who delivered an infant at 41 weeks of gestation. The EMA-based measure of negative affect was associated with higher cortisol throughout the day (p = .006) but not to gestational length (p = .641). The one-time measure of cortisol was not associated with length of gestation, and traditional retrospective recall measures of negative affect were not associated with cortisol. CONCLUSIONS: Our findings support the ecological validity of repeated ambulatory assessments of cortisol in pregnancy and their ability to improve the prediction of adverse birth outcomes.