Prematurity, Birth Weight, and Socioeconomic Status Are Linked to Atypical Diurnal Hypothalamic-Pituitary-Adrenal Axis Activity in Young Adults

Preterm birth: A neuroinflammatory origin for metabolic diseases?

Preterm birth and its related complications have become more and more common as neonatal medicine advances. The concept of "developmental origins of health and disease" has raised awareness of adverse perinatal events in the development of diseases later in life. To explore this concept, we propose that encephalopathy of prematurity (EoP) as a potential pro-inflammatory early life event becomes a novel risk factor for metabolic diseases in children/adolescents and adulthood. Here, we review epidemiological evidence that links preterm birth to metabolic diseases and discuss possible synergic roles of preterm birth and neuroinflammation from EoP in the development of metabolic diseases. In addition, we explore theoretical underlying mechanisms regarding developmental programming of the energy control system and HPA axis.

Cortisol reactivity and negative affect among preterm infants at 12 months during a mother-infant interaction task

The purpose of this study was to investigate correlates of preterm (PT) infant's cortisol reactivity and the association to infant negative affect, during a mother-infant interaction procedure. Participants included 48 infants born prematurely (gestational age < 37 weeks) and their mothers, assessed when infants were 12 months old corrected for prematurity. The examined variables comprised both neonatal and environmental dimensions including maternal interactive behavior. Infant negative affect and maternal interactive behavior were assessed with a standardized mother-infant interaction task. A baseline infant saliva sample was collected before the interaction began, and a second sample after the interaction episodes ended. Results revealed that decrease of infant's cortisol concentration was significantly associated with the exposure to more sensitive, and less intrusive maternal behaviors. However, once controlled for neonatal risk, family SES and maternal psychological distress, the associations were rendered non-significant. Although the association between cortisol reactivity and negative affect trended toward significance, maternal intrusiveness was the only significant predictor of observed infant negative affect. Findings suggest the importance of primary relational experiences on PT infants' early regulatory competencies.

Role of sex in the association between childhood socioeconomic position and cognitive ageing in later life

We aimed to explore sex differences in the association of childhood socioeconomic position (SEP) with the level of cognitive performance and the rate of cognitive decline. We studied 84,059 individuals (55% women; mean age 64 years) from the Survey on Health, Ageing and Retirement in Europe. Sex differences in the association of childhood SEP (household characteristics at age 10) with the level of cognitive performance (verbal fluency, immediate recall, delayed recall) were analysed using multilevel linear regression. Structural equation modelling tested education, depressive symptoms and physical state as mediators. The relationship between childhood socioeconomic advantage and disadvantage and the rate of cognitive decline was assessed using linear mixed-effects models. Higher childhood SEP was associated with a higher level of cognitive performance to a greater extent in women (B = 0.122; 95% CI 0.092–0.151) than in men (B = 0.109; 95% CI 0.084–0.135). The strongest mediator was education. Childhood socioeconomic disadvantage was related to a higher rate of decline in delayed recall in both sexes, with a greater association in women. Strategies to prevent impaired late-life cognitive functioning, such as reducing childhood socioeconomic disadvantages and improving education, might have a greater benefit for women.

Extremely low birth weight influences the relationship between stress and telomere length in adulthood

This study examined the link between two biological markers of stress vulnerability at 22-26 years of age and telomere length at 30-35 among extremely low birth weight (ELBW; <1000 g) survivors and normal birth weight (NBW; >2500 g) control participants. Sixteen ELBW and 22 NBW participants provided baseline afternoon salivary cortisol samples and resting frontal electroencephalogram (EEG) alpha asymmetry data at 22-26 years. Buccal cells were assayed for telomere length at 30-35 years. Analyses controlled for sex, postnatal steroid exposure, childhood socioeconomic status, time of cortisol sample collection, and body mass index at 22-26 years. Salivary cortisol and frontal asymmetry at age 22-26 independently predicted telomere length at age 30-35, such that relatively higher cortisol and greater relative right frontal asymmetry at rest predicted telomere shortening among NBW controls, but not among ELBW survivors. However, similar associations were not noted in ELBW survivors, suggesting that ELBW survivors may have different mechanisms of stress coping as a result of their early-life exposures. These findings offer preliminary evidence in support of the role of stress in the genesis of cellular senescence at least among those born at NBW, but that these links may differ in those born preterm.

Influence of race on the effect of premature birth on salivary cortisol response to stress in adolescents

BACKGROUND

Adolescents born preterm have altered hypothalamic-pituitary-adrenal axis function with a blunted cortisol stress response, however, the influences of intrauterine growth restriction and race are unclear.

METHODS

We measured salivary cortisol before and 20 min after a maximal-exercise stress test and calculated the cortisol stress response. We used linear regression to compare cortisol stress responses between preterm and term groups, adjusting for birth weight z-score and maternal hypertension, and examined effect modification by race and sex.

RESULTS

We evaluated 171 adolescents born preterm with very low birth weight and 50 born term. Adolescents born preterm had reduced cortisol stress response compared to term (0.03 vs. 0.08 μg/dL, p = 0.04). This difference was race dependent: non-Black adolescents born preterm had significantly reduced cortisol stress response compared to those born at term (adjusted β: -0.74; 95% CI -1.34, -0.15), while there was no difference in Black adolescents (0.53; -0.16, 1.22). Sex did not modify the relationship.

CONCLUSIONS

Adolescents born preterm exhibit a reduced salivary cortisol response to exercise stress, suggesting long-term alterations in the hypothalamic-pituitary-adrenal axis. This relationship was evident in non-Black but not in Black adolescents, suggesting that race may modify the influence of preterm birth on stress alterations of the hypothalamic-pituitary-adrenal axis.

Prenatal and childhood predictors of hair cortisol concentration in mid-childhood and early adolescence

Background

Hair cortisol concentration (HCC) is an increasingly used measure of systemic cortisol concentration. However, determinants of HCC in children and adolescents are unclear because few prospective studies have been conducted to date.

Study design

We followed 725 children in Project Viva, a pre-birth cohort study of mothers and children, who provided hair samples at mid-childhood (median age: 7.7 years) or early adolescence (median age: 12.9 years). We examined associations of various factors measured from pregnancy to mid-childhood with HCC in mid-childhood and early adolescence, as well as change in HCC between these time points (ΔHCC).

Results

There were 426 children with HCC measurements in both mid-childhood and early adolescence, 173 children with measures only in mid-childhood, and 126 with measures only in early adolescence. HCC was lower in mid-childhood (median 1.0pg/mg [interquartile range, IQR: 0.5, 2.4]) than early adolescence (2.2pg/mg [1.1, 4.4]). In multivariable-adjusted regression models, female sex (β = -0.41, 95% CI: -0.67, -0.15) and birth weight-for-gestational age z-score (β = -0.19, 95% CI: -0.33, -0.04) were associated with lower mid-childhood HCC, while prenatal smoking was associated with higher mid-childhood HCC (β = 0.53, 95% CI: 0.04, 1.01). In early adolescence, child age (β = 0.34 per year, 95% CI: 0.21, 0.46) female sex (β = 0.33, 95% CI: 0.10, 0.57), and maternal pre-pregnancy body mass index (β = 0.15 per 5-kg/m², 95% CI: 0.01, 0.29) were positively associated with HCC. Child anthropometric measures and biomarker concentrations were not associated with HCC.

Conclusion

Maternal pre-pregnancy BMI, maternal prenatal smoking, and low birth weight were associated with higher mid-childhood and adolescent HCC. However, few postnatal characteristics were associated with HCC.

Weight Gain and Blood Pressure in Toddlers Born Very Preterm

BACKGROUND

Preterm birth is a risk factor for elevated blood pressure in childhood and the development of hypertension and cardiometabolic disease in adulthood; however, mechanisms for the development of both are poorly understood. Rapid weight gain early in childhood may serve as a driver directly and indirectly through cortisol levels found to be elevated in early childhood in individuals born preterm.

OBJECTIVES

The objective of this pilot study was to examine the effect sizes of the relationships between weight gain and blood pressure in toddlers born very preterm. A secondary aim was to note any mediating effect of cortisol on the relationships between weight gain and blood pressure.

METHODS

A cross-sectional design with a convenience sample of 36 toddlers who were born very preterm was used to examine the relationships between postnatal weight gain, cortisol, and blood pressure at follow-up.

RESULTS

Many of the participants experienced rapid weight gain in the first 12 months of life. Mean systolic and diastolic readings were 94 and 56.6, respectively. Diastolic blood pressure readings were obtained from 23 participants, and the majority were elevated. Weight gain was associated with diastolic blood pressure with a medium effect size. A mediating role with cortisol was not supported.

DISCUSSION

Although findings need to be validated in a larger sample, the blood pressure elevations in this sample were alarming. If readings continue to amplify as these children age, the fact that elevations are already present during the toddler period could indicate more significant cardiovascular disease in adulthood for this population. Rapid weight gain in early life may be a driver for elevated blood pressure even during early childhood in individuals born preterm.

Prematurity and cardiovascular risk at early adulthood

BACKGROUND

Theories of early stress exposure and allostatic load offer a lifespan perspective to adult health after prematurity based on these early stressors affecting endocrine and metabolic systems. In this study, we examine cardiovascular and metabolic risk by comparing two groups of preterm infants who experienced a full spectrum of neonatal illness and a term-born group at age 23.

METHODS

Of the 215 infants recruited at birth, 84% participated at age 23. The cohort included 45 full-term (FT), 24 healthy preterm (HPT), and 111 sick preterm (SPT) infants. Socio-economic status was equivalent across groups. Cardiovascular and metabolic outcomes were as follows: blood pressure (BP), fasting glucose and lipid profiles, weight, waist-hip ratio (WHR), and body mass index (BMI). Clinical and subclinical ranges were compared across neonatal groups and gender.

RESULTS

At age 23, the HPT and SPT groups had higher systolic BP compared with the FT group. The SPT group had lower weight compared with the FT and HPT groups. No group differences were found on diastolic BP, glucose, total cholesterol, high-density lipids, low-density lipids, triglycerides, BMI, or WHR. Preterm males had more systolic hypertension and low high-density lipids than FT males. Former preterm males and females had high WHR ratios and BMI at 23 years. Subclinical prehypertensive rates were highest for the HPT female group, followed by the SPT females. Only one (4.2%) HPT adult male was clinically diabetic.

CONCLUSIONS

As young adults, HPT and SPT infants had early indicators of cardiovascular risk but no indicators of metabolic risk. There is utility in using clinical and subclinical ranges to identify early cardiovascular risk in early adulthood.

Prematurity and perinatal adversity effects hypothalamic-pituitary-adrenal axis reactivity to social evaluative threat in adulthood

This study examined the long-term effects of prematurity and perinatal adversity on individual differences in stress-related reactivity and regulation of the HPA axis. A prospective sample of 155 infants born preterm and healthy (n = 20), medical illness (n = 48), neurological illness (n = 26), and small for gestational age (n = 24) and full-term (n = 37) were recruited between 1985 and 1989. At age 23 years, multiple saliva samples were collected before and after participation in the Trier Social Stress Test and later assayed for cortisol. Results reveal that at age 23 years, infants born premature with neurological complications showed higher cortisol reactivity to social evaluative threat compared to either their full-term, small for gestation age, medically ill, or healthy preterm peers. Findings are discussed in terms of implications for contemporary theories that propose effects of early adversity on biological sensitivities and susceptibilities, which translate experience into developmental outcomes related to poor health and risk for disease.

Self-Reported Mental Health Problems Among Adults Born Preterm: A Meta-analysis

CONTEXT

Preterm birth increases the risk for mental disorders in adulthood, yet findings on self-reported or subclinical mental health problems are mixed.

OBJECTIVE

To study self-reported mental health problems among adults born preterm at very low birth weight (VLBW; ≤1500 g) compared with term controls in an individual participant data meta-analysis.

DATA SOURCES

Adults Born Preterm International Collaboration.

STUDY SELECTION

Studies that compared self-reported mental health problems using the Achenbach Young Adult Self Report or Adult Self Report between adults born preterm at VLBW (n = 747) and at term (n = 1512).

DATA EXTRACTION

We obtained individual participant data from 6 study cohorts and compared preterm and control groups by mixed random coefficient linear and Tobit regression.

RESULTS

Adults born preterm reported more internalizing (pooled β = .06; 95% confidence interval .01 to .11) and avoidant personality problems (.11; .05 to .17), and less externalizing (-.10; -.15 to -.06), rule breaking (-.10; -.15 to -.05), intrusive behavior (-.14; -.19 to -.09), and antisocial personality problems (-.09; -.14 to -.04) than controls. Group differences did not systematically vary by sex, intrauterine growth pattern, neurosensory impairments, or study cohort.

LIMITATIONS

Exclusively self-reported data are not confirmed by alternative data sources.

CONCLUSIONS

Self-reports of adults born preterm at VLBW reveal a heightened risk for internalizing problems and socially avoidant personality traits together with a lowered risk for externalizing problem types. Our findings support the view that preterm birth constitutes an early vulnerability factor with long-term consequences on the individual into adulthood.