The effects of preterm birth and its antecedents on the cardiovascular system

PPARγ drives mitochondrial stress signaling and the loss of atrial cardiomyocytes in newborn mice exposed to hyperoxia

Diastolic dysfunction is increasingly common in preterm infants exposed to supplemental oxygen (hyperoxia). Previous studies in neonatal mice showed hyperoxia suppresses fatty acid synthesis genes required for proliferation and survival of atrial cardiomyocytes. The loss of atrial cardiomyocytes creates a hypoplastic left atrium that inappropriately fills the left ventricle during diastole. Here, we show that hyperoxia stimulates adenosine monophosphate-activated kinase (AMPK) and peroxisome proliferator activated receptor-gamma (PPARγ) signaling in atrial cardiomyocytes. While both pathways can regulate lipid homeostasis, PPARγ was the primary pathway by which hyperoxia inhibits fatty acid gene expression and inhibits proliferation of mouse atrial HL-1 cells. It also enhanced the toxicity of hyperoxia by increasing expression of activating transcription factor (ATF) 5 and other mitochondrial stress response genes. Silencing PPARγ signaling restored proliferation and survival of HL-1 cells as well as atrial cardiomyocytes in neonatal mice exposed to hyperoxia. Our findings reveal PPARγ enhances the toxicity of hyperoxia on atrial cardiomyocytes, thus suggesting inhibitors of PPARγ signaling may prevent diastolic dysfunction in preterm infants.

Transferring an extremely premature infant to an extra-uterine life support system: a prospective view on the obstetric procedure

To improve care for extremely premature infants, the development of an extrauterine environment for newborn development is being researched, known as Artificial Placenta and Artificial Womb (APAW) technology. APAW facilitates extended development in a liquid-filled incubator with oxygen and nutrient supply through an oxygenator connected to the umbilical vessels. This setup is intended to provide the optimal environment for further development, allowing further lung maturation by delaying gas exposure to oxygen. This innovative treatment necessitates interventions in obstetric procedures to transfer an infant from the native to an artificial womb, while preventing fetal-to-neonatal transition. In this narrative review we analyze relevant fetal physiology literature, provide an overview of insights from APAW studies, and identify considerations for the obstetric procedure from the native uterus to an APAW system. Lastly, this review provides suggestions to improve sterility, fetal and maternal well-being, and the prevention of neonatal transition.

Maternal Occupational Risk Factors and Preterm Birth: A Systematic Review and Meta-Analysis

Objective: This systematic review and meta-analysis aimed to summarize the evidence on the relationship between physical occupational risks (high physical workload, long working hours, shift work, whole-body vibrations, prolonged standing, and heavy lifting) and preterm birth. Methods: A systematic review and meta-analysis was conducted across six databases to investigate the relationship between physical occupational risks and preterm birth. Result: A comprehensive analysis of 37 studies with varying sample sizes found moderate evidence of positive associations between high physical workload, long working hours, shift work, whole-body vibration, and preterm birth. Meta-analysis showed a 44% higher risk (OR 1.44, 95% CI 1.25-1.66) for preterm birth with long working hours and a 63% higher risk (OR 1.63, 95% CI 1.03-2.58) with shift work. Conclusion: Pregnant women in physically demanding jobs, those working long hours or on shifts, and those exposed to whole-body vibration have an increased risk of preterm birth. Employers should establish supportive workplaces, policymakers implement protective measures, healthcare providers conduct screenings, and pregnant women must stay informed and mitigate these job-related risks. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/], Identifier [CRD42022357045].

Maternal occupational risk factors and preterm birth: Protocol for a systematic review and meta-analysis

INTRODUCTION

Preterm birth, which accounts for 33.1% of neonatal death globally, is the main cause of under-five mortality. A growing number of studies indicate that occupational risk factors during pregnancy are linked to an increased likelihood of poor pregnancy outcomes. The effect of physical occupational risks on preterm birth has received very little attention, and previous reviews have produced inconclusive results. This systematic review aims to update the evidence on the relationship between maternal physical occupational risks and preterm birth.

METHOD AND ANALYSIS

We will search electronic databases including Ovid Medline, Embase, Emcare, CINAHL, Scopus, and Web of science to find peer-reviewed studies examining the relationship between six common maternal physical occupational risks (heavy lifting, prolonged standing, heavy physical exertion, long working hours, shift work, and whole-body vibrations) and preterm birth. Articles published in English after 1 January 2000 will be included without geographic restrictions. Two reviewers will screen titles and abstracts independently, and then select full-text articles that meet inclusion criteria. Methodological quality of the included studies will be evaluated using the Joanna Briggs Institute (JBI) critical appraisal method. The quality of evidence across each exposure and the outcome of interest will be examined by using the GRADE (Grade of Recommendations, Assessment, Development, Evaluation) method. Accordingly, a high level of evidence will lead to "strong recommendations". A moderate level of evidence will lead to "practice considerations". For all evidence levels below moderate, the message will be "not enough evidence from the scientific literature to guide policymakers, clinicians, and patients. If data permits, a meta-analysis will be conducted using Stata Software. In case where meta-analysis is not possible, we will perform a formal narrative synthesis.

DISCUSSION AND CONCLUSION

Evidence suggests that preterm birth is linked to a number of maternal occupational risk factors. This systematic review will update, compile, and critically review the evidence on the effect of maternal physical occupational risk on preterm birth. This systematic review will provide guidance to support decision-makers including maternal and child health services, other health care providers, and government policy agencies.

TRIAL REGISTRATION

PROSPERO registration number: CRD42022357045.

Echocardiographic assessment of brain sparing in small-for-gestational age infants and association with neonatal outcomes

Brain sparing is an adaptive phenomenon (redistribution of blood flow to the brain) observed in fetuses exposed to chronic hypoxia, who are at risk of intrauterine growth restriction. Here, we assessed the blood flow distribution during the early neonatal period (< 7 days of life) using echocardiography, and evaluated the impact of brain-sparing on postnatal course and neurodevelopmental outcomes. This retrospective study included 42 small-for-gestational age (SGA) infants [further classified into asymmetric SGA (a-SGA, n = 21) and symmetric SGA (s-SGA, n = 21) groups according to their birth head circumference percentiles], and 1: 2 matched appropriate-for-gestational age (AGA) infants (n = 84) admitted to the neonatal intensive care unit. Left ventricular (LV) stroke volume, LV cardiac output (LVCO), upper body blood flow (UBBF), and UBBF/LVCO ratio (%) were significantly higher in both a-SGA and s-SGA infants than in AGA infants. Both a-SGA and s-SGA groups consisted predominantly of infants with higher UBBF/LVCO (%). A UBBF/LVCO ≥ 58.2% (3rd interquartile range) was associated with a later need for rehabilitative therapy after discharge. In summary, brain-sparing effect may continue during the early postnatal life in SGA infants, and may be a promising marker to detect future adverse neurodevelopmental outcomes.

Segregated by Wealth, Health, and Development: An Analysis of Pre-School Child Health in a Medium-Sized German City

The School Entry Examination (SEE) can be used to identify children with current health issues, developmental delays, and risk factors for later diseases. This study analyzes the health status of preschool children in a German city with considerable socio-economic differences among its quarters. We used secondary data from SEEs 2016-2019 from the entire city (8417 children), which we divided into quarters with low (LSEB), medium (MSEB), and high socioeconomic burden (HSEB). In HSEB quarters, 11.3% of children were overweight as opposed to 5.3% in LSEB quarters. In HSEB quarters, 17.2% of children had sub-par cognitive development in contrast to 1.5% in LSEB quarters. For overall sub-par development, LSEB quarters had a prevalence of 3.3%, whereas, in HSEB quarters, 35.8% of children received this result. Logistic regression was used to determine the influence of the city quarter on the outcome of overall sub-par development. Here, considerable disparities among HSEB and LSEB quarters remained after adjustment for parents' employment status and education. Pre-school children in HSEB quarters showed a higher risk for later disease than children in LSEB quarters. The city quarter had an association with child health and development that should be considered in the formulation of interventions.

Application of Life's Essential 8 to assess cardiovascular health during early childhood

PURPOSE

Assess cardiovascular health (CVH) during early childhood using the American Heart Association's recently updated construct, Life's Essential 8 (LE8); examine concordance in CVH status per LE8 versus Life's Simple 7 (LS7); and identify perinatal correlates of high CVH per LE8.

METHODS

We applied LE8 and LS7 to data from 305 children aged 4-7 years in Denver, CO; estimated % low, moderate, high, and optimal CVH; assessed concordance in CVH status based on LE8 and LS7 using contingency tables; and used multivariable logistic regression to identify early-life correlates of high CVH per LE8.

RESULTS

Average age of children was 4.7 ± 0.6 years, 44.6% were female. No participants had low or optimal CVH, 43.9% had high, and 56.1% had moderate CVH per LE8, whereas 33.4% had high and 66.6% had moderate CVH per LS7. Twenty-two percent had high CVH based on both constructs. Correlates of high CVH were maternal prenatal diet quality (odds ratioHealthy Eating Index score>vs. ≤57 = 1.90 [1.12, 3.21]) and child age (odds ratioper 1 year = 1.58 [1.04. 2.42]).

CONCLUSIONS

LE8 yielded higher prevalence of high CVH than LS7 during early childhood, though there is modest concordance between the two constructs. Maternal diet is a potential modifiable target to optimize early-life CVH.

Effects of Acute and Chronic Trypanosoma cruzi Infection on Pregnancy Outcomes in Mice: Parasite Transmission, Mortality, Delayed Growth, and Organ Damage in Pups

Chagas disease is caused by Trypanosoma cruzi. This study aimed to determine the effects of T. cruzi infection on fertility rate and health of the newborn pups in pregnant mice. Female mice were challenged with T. cruzi and mated at 21 days (acute parasitemic phase) or 90 days (chronic parasite persistence phase) after infection. Pups were examined for growth up to 20 days after birth; and parasite burden in brain, heart, skeletal muscle, and intestine was measured by real-time quantitative PCR. The inflammatory infiltrate, necrosis, and fibrosis in pups' heart and brain tissues were evaluated by histology. T. cruzi infection in dams delayed the onset of pregnancy, decreased the fertility rate, and led to vertical transmission of parasite to the pups. Furthermore, infected dams delivered pups that exhibited decreased survival rate, decreased birth weight, and decreased growth rate. Significantly increased inflammation, necrosis, and fibrosis of cardiac and brain tissues were noted in pups born to infected dams. Initial challenge with higher parasite dose had more detrimental effects on fertility rate and pups' health in both acutely and chronically infected dams. In conclusion, mice offer a promising model to evaluate the efficacy of new vaccines and therapeutic drugs in controlling the acute and chronic maternal T. cruzi infection and congenital transmission to newborns, and in improving the fertility rate and pups' health outcomes.

Features of left ventricle longitudinal strain in children from one to five years old, born with low, very low, and extremely low body weight

Purpose. The study assessed left ventricle longitudinal strain of the endocardial, middle, and epicardial layers in children from one to five years old, born with low, very low, and extremely low body weight.Material and methods. The study was performed in 204 children aged from one to five years; of these, 53 children were prematurely born late in pregnancy, 103 children were born very preterm, and 48 children were born healthy and full-term. The left ventricle longitudinal strain of the endocardial, middle, and epicardial layers was assessed off-line using the Speckle Tracking Imaging-2D Strain technology.Results. Disturbance of the transmural gradient strain of left ventricle wall were detected in 11.32% of prematurely born late in pregnancy children and in 16.5% of very preterm children. A decrease of left ventricle segments strain was registered in 33.96% of children prematurely born late in pregnancy and in 18.44% very preterm children. In children of the same age, born healthy and full-term, transmural wall gradient disturbances and decrease of strain in left ventricle segments were not observed. In children prematurely born late in pregnancy, the disturbance of the transmural strain gradient of left ventricle and the decrease of strain in left ventricle segments are not associated with left ventricle remodeling.Conclusion. The development of the cardiovascular system in children of early and preschool age, born prematurely with low, very low, and extremely low body weight, is characterized by disturbances in the transmural strain gradient of left ventricle wall, due to the processes of postnatal growth and development of the child’s heart, which requires monitoring on an outpatient basis in polyclinic in childhood — by a pediatric cardiologist and a pediatrician, and in adulthood — by a cardiologist and therapist.

Effect of preterm birth in rats on proliferation and hyperplasia of cardiomyocytes

Aim. To identify the effect of preterm birth on proliferation and hyperplasia of cardiomyocytes in the early postnatal period of ontogenesis in rats.

Materials and methods. Preterm birth (on day 21 and 21.5 of gestation) in Wistar rats was induced by subcutaneous administration of mifepristone. Immunohistochemistry was used to identify and calculate the number of Ki67-positive and Mklp2-positive cardiomyocytes in the left ventricle of preterm and full-term rats on days 1, 2, 3, 4, 5, and 6 of postnatal ontogenesis. Statistical analysis of morphometric parameters was performed using the Shapiro – Wilk test and Mann – Whitney test with the Bonferroni correction.

Results. We revealed an increase in the number of Ki67-positive cardiomyocytes in the left ventricle of the rats: on day 1 of postnatal ontogenesis (in the rats born on day 21 of gestation) and on days 3–5 of postnatal ontogenesis (in the rats born on day 21.5 of gestation). Preterm birth in rats did not result in a change in the number of Mklp2-positive cardiomyocytes in the left ventricular wall.

Conclusion. A change in the pattern of Ki67 expression by cardiomyocytes in the rats born 12 or 24 hours before full term was demonstrated in the early postnatal period of ontogenesis. An isolated increase in Ki67 expression without a change in Mklp2 expression by cardiomyocytes in the left ventricular wall of preterm rats indicates acceleration of cardiomyocyte hypertrophy. Shorter duration of prenatal development is associated with more pronounced morphological and functional rearrangements in the rat myocardium.

Avaliação Eletrocardiográfica de Recém-Nascidos Normais na Primeira Semana de Vida – Estudo Observacional

Fundamento

O período neonatal é marcado por muitas alterações importantes no sistema cardiovascular, principalmente na primeira semana de vida. Diferentemente da população adulta, estudos sobre dados de eletrocardiograma (ECG) no período neonatal são escassos. Este é o primeiro estudo a descrever alterações eletrocardiográficas em uma coorte de recém-nascidos com ecocardiogramas normais.

Objetivos

Analisar padrões eletrocardiográficos de uma população de recém-nascidos a termo, sem anomalias morfológicas ou funcionais cardíacas, e comparar os resultados com a literatura.

Métodos

Neste estudo observacional, ecocardiogramas e resultados de ECG de 94 neonatos divididos em três grupos etários (até 24 horas, entre 25 e 72 horas, e entre 73 e 168 horas de vida) foram avaliados e comparados com aqueles descritos por Davignon et al. Um valor de p < 0,05 foi considerado estatisticamente significativo.

Resultados

Diferenças significativas na direção da onda T foram detectadas nas derivações V1 (p= 0,04), V2 (p= 0,02), V3 (p= 0,008) e V4 (p= 0,005). Houve diferenças entre nossos resultados e a literatura atual na maioria dos parâmetros.

Conclusão

Recém-nascidos a termo com menos de 24 horas de vida apresentaram significativamente mais ondas T positivas que aqueles com mais horas de vida. Encontramos muitas diferenças nos parâmetros de ECG em comparação aos descritos por Davignon et al., particularmente nas amplitudes de P, Q, R, S, duração do QRS, R/S e R+S. Esses achados indicam a necessidade de mais estudos para uma interpretação definitiva do ECG em recém-nascidos.

Cardiac cycle: an observational/interventional study protocol to characterise cardiopulmonary function and evaluate a home-based cycling program in children and adolescents born extremely preterm

INTRODUCTION

Extremely preterm (EP)/extremely low birthweight (ELBW) individuals may have an increased risk for adverse cardiovascular outcomes. Compared with term-born controls, these individuals have poorer lung function and reduced exercise capacity. Exercise interventions play an important role in reducing cardiopulmonary risk, however their use in EP/ELBW cohorts is unknown. This study, cardiac cycle, aims to characterise the cardiopulmonary system of children and adolescents who were born EP compared with those born at term, following acute and chronic exercise bouts.

METHODS AND ANALYSIS

The single-centre study comprises a home-based exercise intervention, with physiological characterisation at baseline and after completion of the intervention. Fifty-eight children and adolescents aged 10-18 years who were born EP and/or with ELBW will be recruited. Cardiopulmonary function assessed via measures of blood pressure, arterial stiffness, capillary density, peak oxygen consumption, lung clearance indexes and ventricular structure/function, will be compared with 58 age-matched and sex-matched term-born controls at baseline and post intervention. The intervention will consist of a 10-week stationary cycling programme, utilising Zwift technology.

ETHICS AND DISSEMINATION

The study is approved by the Ethics Committee of the Royal Children's Hospital Melbourne under HREC2019.053. Results will be disseminated via peer-reviewed journal regardless of outcome.

TRIAL REGISTRATION NUMBER

12619000539134, ANZCTR.

Understanding the Preterm Human Heart: What do We Know So Far?

Globally, preterm birth affects more than one in every 10 live births. Although the short‐term cardiopulmonary complications of prematurity are well known, long‐term health effects are only now becoming apparent. Indeed, preterm birth has been associated with elevated cardiovascular morbidity and mortality in adulthood. Experimental animal models and observational human studies point toward changes in heart morphology and function from birth to adulthood in people born preterm that may contribute to known long‐term risks. Moreover, recent data support the notion of a heterogeneous cardiac phenotype of prematurity, which is likely driven by various maternal, early, and late life factors. This review aims to describe the early fetal‐to‐neonatal transition in preterm birth, the different structural and functional changes of the preterm human heart across developmental stages, as well as potential factors contributing to the cardiac phenotype of prematurity.

Developmental Differences in Left Ventricular Strain in IUGR vs. Control Children the First Three Months of Life

BACKGROUND

Intrauterine growth restriction (IUGR) may directly affect cardiovascular function in early life. Longitudinal data on left ventricular longitudinal strain (LVLS), a key measure of cardiac function independent of body size, is not available. We hypothesize impaired cardiac function among IUGR newborns and persistence of the impairment until age 3 months.

METHOD

This is a prospective cohort study of consecutive pregnancies where IUGR was identified at 18-38 weeks gestational age (GA) with healthy controls randomly selected at 18-20 weeks GA. Echocardiograms were performed at birth and at age 3-4 months, and then compared.

RESULTS

At birth, mean (SD) LVLS did not differ between the IUGR group [N = 19; - 15.76 (3.12) %] and controls [N = 35; - 15.53 (3.56) %]. The IUGR group demonstrated no significant change in LVLS at age 3-4 months [- 17.80 (3.82) %], while the control group [- 20.91 (3.31) %] showed a significant increase (P < 0.001). Thus, LVLS was lower in the IUGR group at age 3-4 months (P = 0.003).

CONCLUSION

The lack of increase in LVLS may suggest that IUGR has a direct impact on cardiac function as early as during the first months of life. Trial registration Clinical trials.gov Identifier: NCT02583763, registration October 22, 2015. Retrospectively registered September 2014-October 2015, thereafter, registered prospectively.

Cardiac structure and function in very preterm-born adolescents compared to term-born controls: A longitudinal cohort study

BACKGROUND

There is emerging evidence of differences in cardiac structure and function in preterm-born adults and increased risk of heart failure. However, there is a paucity of data in populations who have been exposed to modern intensive care and the impact of perinatal factors is unclear.

AIMS

To compare echocardiographic measures of cardiac structure and function in a regional cohort of 17-year-olds born very preterm compared to term-born peers and the influence of perinatal factors.

STUDY DESIGN

Observational longitudinal cohort study.

SUBJECTS

A regional cohort of ninety-one 17-year-olds born at <32 weeks gestation compared to sixty-two term-born controls.

OUTCOME MEASURES

Echocardiographic measures of cardiac structure and function.

RESULTS

Left ventricular and right atrial volume and left ventricular mass, indexed to body surface area, were significantly smaller in preterm-born adolescents compared to term-born controls even when adjusted for sex. There were no between group differences in cardiac function. Within those born preterm we found a significant association between gestational age and birthweight z-score and measures of cardiac function at 17 years. Within the preterm group, those with a diagnosis of bronchopulmonary dysplasia had higher left ventricular posterior wall thickness, higher mitral deceleration time and lower left atrial area and tricuspid annular plane of systolic excursion.

CONCLUSIONS

Adolescents born very prematurely, who have received modern intensive care, have measurable differences in heart structure compared to their term-born peers but heart function is preserved. For those born preterm, gestational age, birthweight and bronchopulmonary dysplasia are associated with differences in cardiac function.

Right Ventricular Structure and Function in Young Adults Born Preterm at Very Low Birth Weight

Being born preterm (PT, <37 weeks gestation) or at very low birth weight (VLBW, <1500 g) is associated with increased rates of cardiopulmonary disorders in childhood. As survivors age, late cardiac effects, including right ventricular (RV) remodelling and occult pulmonary hypertension are emerging. In this population-based study, we aimed to investigate right heart structure and function in young adults born PT at VLBW compared to normal-weight term-born controls. The New Zealand VLBW Study has followed all infants born in 1986 with birth weight <1500 g. All were born preterm from 24 to 37 weeks. A total of 229 (71% of survivors) had echocardiograms aged 26–30 years which were compared to age-matched, term-born, normal-weight controls (n = 100). Young adults born preterm at very low birth weight exhibited smaller RV dimensions compared to term-born peers. Standard echocardiographic measures of RV function did not differ, but mildly reduced function was detected by RV longitudinal strain. This difference was related to birth weight and gestational age but not lung function or left ventricular function. Echocardiographic strain imaging may be an important tool to detect differences in RV function preterm and VLBW.

Effect of Preterm Birth on Cardiac and Cardiomyocyte Growth and the Consequences of Antenatal and Postnatal Glucocorticoid Treatment

Preterm birth coincides with a key developmental window of cardiac growth and maturation, and thus has the potential to influence long-term cardiac function. Individuals born preterm have structural cardiac remodelling and altered cardiac growth and function by early adulthood. The evidence linking preterm birth and cardiovascular disease in later life is mounting. Advances in the perinatal care of preterm infants, such as glucocorticoid therapy, have improved survival rates, but at what cost? This review highlights the short-term and long-term impact of preterm birth on the structure and function of the heart and focuses on the impact of antenatal and postnatal glucocorticoid treatment on the immature preterm heart.

Preterm Birth With Neonatal Interventions Accelerates Collagen Deposition in the Left Ventricle of Lambs Without Affecting Cardiomyocyte Development

Background

Adults born preterm (< 37 weeks’ gestation) exhibit altered cardiac growth and are susceptible to cardiac dysfunction. Sheep studies have shown that moderate preterm birth results in maladaptive structural remodelling of the cardiac ventricles. The aim of this study was to examine ventricular structure in lambs born at a greater severity of preterm birth and ventilated postnatally.

Methods

Former-preterm lambs delivered at 128 days’ gestation, and mechanically ventilated for a week after birth, were compared with unventilated lambs born at term (150 days’ gestation), at 2 months (term: n = 10, former-preterm: n = 8), and 5 months (term: n = 9, former-preterm: n = 8) term-equivalent age. The right ventricle and left ventricle plus septum were analysed using immunohistochemistry, histology, and stereology.

Results

Cardiomyocyte number, cross-sectional area, proliferation, and apoptosis were not affected by preterm birth or age. Left ventricle plus septum interstitial collagen levels increased with age (P = 0.0015) and were exacerbated by preterm birth (P = 0.0006; 2 months term: 0.57% ± 0.07%, former-preterm: 1.44% ± 0.18%; 5 months term: 1.37% ± 0.25%, former-preterm: 2.15% ± 0.31%). Right ventricle interstitial collagen levels increased with age (P = 0.012) but were not affected by preterm birth.

Conclusion

This study is the first to explore the effect of preterm birth combined with modern neonatal interventions on the ventricular myocardium in lambs. There was no adverse impact on cardiomyocyte growth in early postnatal life. Of concern, however, there was increased collagen deposition in the preterm hearts, which has the potential to induce cardiac dysfunction, especially if it becomes exaggerated with ageing.

Neonatal hyperoxia impairs adipogenesis of bone marrow-derived mesenchymal stem cells and fat accumulation in adult mice

Preterm birth is a risk factor for growth failure and development of respiratory disease in children and young adults. Their early exposure to oxygen may contribute to lung disease because adult mice exposed to hyperoxia as neonates display reduced lung function, changes in the host response to respiratory viral infections, and develop pulmonary hypertension and heart failure that shortens their lifespan. Here, we provide new evidence that neonatal hyperoxia also impairs growth by inhibiting fat accumulation. Failure to accumulate fat may reflect a systemic defect in adipogenic potential of stem cells because bone marrow-derived mesenchymal cells (BMSCs) isolated from the mice grew slower and were more oxidized compared to controls. They also displayed reduced capacity to accumulate lipid and differentiate into adipocytes. BMSCs from adult mice exposed to neonatal hyperoxia express lower levels of peroxisome proliferator-activated receptor gamma (PPARγ), a transcription factor that drives adipocyte differentiation. The defect in adipogenesis was rescued by expressing PPARγ in these cells. These findings reveal early life exposure to high levels of oxygen may suppresses fat accumulation and impair adipogenic differentiation upstream of PPARγ signaling, thus potentially contributing to growth failure seen in people born preterm.

DNA Methylation, Preterm Birth and Blood Pressure in African American Children: The DPREG Study

Preterm birth (< 37 weeks) has been associated with high blood pressure (BP) and cardiovascular disease in adulthood. Epigenetic mechanisms may explain how preterm birth influences later BP. In this study, we examined the association between DNA methylation (DNAm), preterm birth and BP in African American children. We recruited 100 children and collected clinical and birth history data. DNA was extracted from saliva and the Illumina EPIC BeadChip was used for epigenetic analyses. Preterm birth was not associated with systolic or diastolic BP. No significant DNAm sites were associated with preterm birth in candidate gene methylation analyses. Body mass index was associated with systolic BP (p = 0.01). We did not observe an effect of preterm birth on DNAm or BP in early childhood. Our study is one of the few, however, to examine these associations among African Americans.

Neonatal hyperoxia inhibits proliferation and survival of atrial cardiomyocytes by suppressing fatty acid synthesis

Preterm birth increases the risk for pulmonary hypertension and heart failure in adulthood. Oxygen therapy can damage the immature cardiopulmonary system and may be partially responsible for the cardiovascular disease in adults born preterm. We previously showed that exposing newborn mice to hyperoxia causes pulmonary hypertension by 1 year of age that is preceded by a poorly understood loss of pulmonary vein cardiomyocyte proliferation. We now show that hyperoxia also reduces cardiomyocyte proliferation and survival in the left atrium and causes diastolic heart failure by disrupting its filling of the left ventricle. Transcriptomic profiling showed that neonatal hyperoxia permanently suppressed fatty acid synthase (Fasn), stearoyl-CoA desaturase 1 (Scd1), and other fatty acid synthesis genes in the atria of mice, the HL-1 line of mouse atrial cardiomyocytes, and left atrial tissue explanted from human infants. Suppressing Fasn or Scd1 reduced HL-1 cell proliferation and increased cell death, while overexpressing these genes maintained their expansion in hyperoxia, suggesting that oxygen directly inhibits atrial cardiomyocyte proliferation and survival by repressing Fasn and Scd1. Pharmacologic interventions that restore Fasn, Scd1, and other fatty acid synthesis genes in atrial cardiomyocytes may, thus, provide a way of ameliorating the adverse effects of supplemental oxygen on preterm infants.

Preterm disparities between foreign and Swedish born mothers depend on the method used to estimate gestational age. A Swedish population-based register study

This study aims to examine whether disparities in gestational age outcomes between foreign and Swedish-born mothers are contingent on the measure used to estimate gestational age and, if so, to identify which maternal factors are associated with the discrepancy. Using population register data, we studied all singleton live births in Sweden from 1992–2012 (n = 1,317,265). Multinomial logistic regression was performed to compare gestational age outcomes classified into very (<32 weeks) and late preterm (32–36 weeks), term and post-term derived from the last menstrual period (LMP) and ultrasound estimates in foreign- and Swedish-born women. Compared to Swedish-born women, foreign-born women had similar odds of very preterm birth (OR: 0.98 [95% CI: 0.98, 1.01]) and lower odds of moderately preterm birth (OR: 0.95 [95% CI: 0.92, 0.98]) based on ultrasound, while higher risks based on LMP (respectively, OR: 1.10 [95% CI: 1.07, 1.14] and 1.09 [95% CI: 1.06, 1.13]). Conclusions on disparities in gestational age-related outcomes by mother’s country of origin depend on the method used to estimate gestational age. Except for very preterm, foreign-born women had a health advantage when gestational age is based on ultrasound, but a health disadvantage when based on LMP. Studies assessing disparities in very preterm birth by migration status are not affected by the estimation method but caution should be taken when interpreting disparities in moderately preterm and preterm birth rates.

Neonatal hyperoxia enhances age-dependent expression of SARS-CoV-2 receptors in mice

The severity of COVID-19 lung disease is higher in the elderly and people with pre-existing co-morbidities. People who were born preterm may be at greater risk for COVID-19 because their early exposure to oxygen (hyperoxia) at birth increases the severity of respiratory viral infections. Hyperoxia at birth increases the severity of influenza A virus infections in adult mice by reducing the number of alveolar epithelial type 2 (AT2) cells. Since AT2 cells express the SARS-CoV-2 receptors angiotensin converting enzyme (ACE2) and transmembrane protease/serine subfamily member 2 (TMPRSS2), their expression should decline as AT2 cells are depleted by hyperoxia. Instead, ACE2 was detected in airway Club cells and endothelial cells at birth, and then AT2 cells at one year of age. Neonatal hyperoxia stimulated expression of ACE2 in Club cells and in AT2 cells by 2 months of age. It also stimulated expression of TMPRSS2 in the lung. Increased expression of SARS-CoV-2 receptors was blocked by mitoTEMPO, a mitochondrial superoxide scavenger that reduced oxidative stress and DNA damage seen in oxygen-exposed mice. Our finding that hyperoxia enhances the age-dependent expression of SARS-CoV-2 receptors in mice helps explain why COVID-19 lung disease is greater in the elderly and people with pre-existing co-morbidities.

Gestational Age and Risk of Mortality in Term-Born Critically Ill Neonates Admitted to PICUs in Australia and New Zealand

OBJECTIVES

Gestational age at birth is declining, probably because more deliveries are being induced. Gestational age is an important modifiable risk factor for neonatal mortality and morbidity. We aimed to investigate the association between gestational age and mortality in hospital for term-born neonates (≥ 37 wk') admitted to PICUs in Australia and New Zealand.

DESIGN

Observational multicenter cohort study.

SETTING

PICUs in Australia and New Zealand.

PATIENTS

Term-born neonates (≥ 37 wk) admitted to PICUs.

INTERVENTIONS

None MEASUREMENTS AND MAIN RESULTS:: We studied 5,073 infants born with a gestational age greater than or equal to 37 weeks and were less than 28 days old when admitted to a PICU in Australia or New Zealand between 2007 and 2016. The association between gestational age and mortality was estimated using a multivariable logistic regression model, adjusting for age, sex, indigenous status, Pediatric Index of Mortality version 2, and site. The median gestational age was 39.1 weeks (interquartile range, 38.2-40 wk) and mortality in hospital was 6.6%. Risk of mortality declined log-linearly with gestational age. The adjusted analysis showed a 20% (95% CI, 11-28%) relative reduction in mortality for each extra week of gestation beyond 37 weeks. The effect of gestation was stronger among those who received extracorporeal life support: each extra week of gestation was associated with a 44% (95% CI, 25-57%) relative reduction in mortality. Longer gestation was also associated with reduced length of stay in hospital: each week increase in gestation, the average length of stay decreased by 4% (95% CI, 2-6%).

CONCLUSIONS

Among neonates born at "term" who are admitted to a PICU, increasing gestational age at birth is associated with a substantial reduction in the risk of dying in hospital. The maturational influence on outcome was more strongly noted in the sickest neonates, such as those requiring extracorporeal life support. This information is important in view of the increasing proportion of planned births in both high- and low-/middle-income countries.

Neonatal hyperoxia enhances age-dependent expression of SARS-CoV-2 receptors in mice

The severity of COVID-19 lung disease is higher in the elderly and people with pre-existing co-morbidities. People who were born preterm may be at greater risk for COVID-19 because their early exposure to oxygen at birth increases their risk of being hospitalized when infected with RSV and other respiratory viruses. Our prior studies in mice showed how high levels of oxygen (hyperoxia) between postnatal days 0-4 increases the severity of influenza A virus infections by reducing the number of alveolar epithelial type 2 (AT2) cells. Because AT2 cells express the SARS-CoV-2 receptors angiotensin converting enzyme (ACE2) and transmembrane protease/serine subfamily member 2 (TMPRSS2), we expected their expression would decline as AT2 cells were depleted by hyperoxia. Instead, we made the surprising discovery that expression of Ace2 and Tmprss2 mRNA increases as mice age and is accelerated by exposing mice to neonatal hyperoxia. ACE2 is primarily expressed at birth by airway Club cells and becomes detectable in AT2 cells by one year of life. Neonatal hyperoxia increases ACE2 expression in Club cells and makes it detectable in 2-month-old AT2 cells. This early and increased expression of SARS-CoV-2 receptors was not seen in adult mice who had been administered the mitochondrial superoxide scavenger mitoTEMPO during hyperoxia. Our finding that early life insults such as hyperoxia enhances the age-dependent expression of SARS-CoV-2 receptors in the respiratory epithelium helps explain why COVID-19 lung disease is greater in the elderly and people with pre-existing co-morbidities.

Early impact of moderate preterm birth on the structure, function and gene expression of conduit arteries

NEW FINDINGS

What is the central question of this study? What is the immediate impact of moderate preterm birth on the structure and function of major conduit arteries using a pre-clinical sheep model? What is the main finding and its importance? Postnatal changes in conduit arteries, including a significant decrease in collagen within the thoracic aortic wall (predominately males), narrowed carotid arteries, reduced aortic systolic blood flow, and upregulation of the mRNA expression of cell adhesion and inflammatory markers at 2 days of age in preterm lambs compared to controls, may increase the risk of cardiovascular impairment in later life.

ABSTRACT

The aim of this work was to compare the structure and function of the conduit arteries of moderately preterm and term-born lambs and to determine whether vascular injury-associated genes were upregulated. Time-mated ewes were induced to deliver either preterm (132 ± 1 days of gestation; n = 11 females and n = 10 males) or at term (147 ± 1 days of gestation; n = 10 females and n = 5 males). Two days after birth, ultrasound imaging of the proximal ascending aorta, main, right and left pulmonary arteries, and right and left common carotid arteries was conducted in anaesthetized lambs. Lambs were then killed and segments of the thoracic aorta and left common carotid artery were either snap frozen for real-time PCR analyses or immersion-fixed for histological quantification of collagen, smooth muscle and elastin within the medial layer. Overall there were few differences in vascular structure between moderately preterm and term lambs. However, there was a significant decrease in the proportion of collagen within the thoracic aortic wall (predominantly in males), narrowing of the common carotid arteries and a reduction in peak aortic systolic blood flow in preterm lambs. In addition, there was increased mRNA expression of the cell adhesion marker P-selectin in the thoracic aortic wall and the pro-inflammatory marker IL-1β in the left common carotid artery in preterm lambs, suggestive of postnatal vascular injury. Early postnatal differences in the function and structure of conduit arteries and evidence of vascular injury in moderately preterm offspring may place them at greater risk of cardiovascular impairment later in life.

Differential Secretion of Angiopoietic Factors and Expression of MicroRNA in Umbilical Cord Blood from Healthy Appropriate-For-Gestational-Age Preterm and Term Newborns-in Search of Biomarkers of Angiogenesis-Related Processes in Preterm Birth

Objectives: Premature birth, defined as less than 37 weeks gestation, affects approximately 12% of all live births around the world. Advances in neonatal care have resulted in the increased survival of infants born prematurely. Although prematurity is a known risk factor for different cardiovascular diseases, little is known about the pathophysiology of vasculature during premature gestation and angiopoietic factors network during premature birth. Aims: The objective of this study was to determine whether the profile of several pro-angiogenic and anti-angiogenic factors in umbilical cord blood (UCB) is different in healthy appropriate-for-gestational-age preterm newborns and normal term babies. The second aim of this study was to investigate the microRNA (miRNAs) expression profile in UCB from preterm labor and to detect miRNAs potentially taking part in control of angogenesis-related processes (Angio-MiRs). Methods: Using an immunobead Luminex assay, we simultaneously measured the concentration of Angiogenin, Angiopoietin-1, FGF-acidic, FGF-basic, PDGF-aa, PlGF, VEGF, VEGF-D, Endostatin, Thrombospondin-2, NGF, BDNF, GDNF, and NT-4 in UCB samples collected from the preterm (n = 27) and term (n = 52) delivery. In addition, the global microRNA expression in peripheral blood mononuclear cells (PBMCs) circulating in such UCB samples was examined in this study using microarray MiRNA technique. Results: The concentrations of five from eight measured pro-angiogenic factors (VEGF, Angiopoietin-1, PDGF-AA, FGF-a, and FGF-b) were significantly lower in UCB from preterm newborns. On the contrary, two angiostatic factors (Endostatin and Thrombospondin-2) were significantly up-regulated in preterm UCB. Among analyzed neurotrophins in preterm newborns, the elevated UCB concentration was found only in the case of GDNF, whereas BDNF was significantly reduced. Moreover, two angiopoietic factors, VEGF-D and PlGF, and two neurotrophins, NT4 and NGF, did not differ in concentration in preterm and term babies. We also discovered that among the significantly down-regulated miRNAs, there were several classical Angio-MiRs (inter alia MiR-125, MiR-126, MiR-145, MiR-150, or MiR155), which are involved in angiogenesis regulation in newborn after preterm delivery. Conclusions: This is the first report of simultaneous measurements of several angiopoietic factors in UCB collected from infants during preterm and term labor. Here, we observed that several pro-angiogenic factors were at lower concentration in UCB collected from preterm newborns than term babies. In contrast, the two measured angiostatic factors, Endostatin and Thrombospondin-2, were significantly higher in UCB from preterm babies. This can suggest that distinct pathophysiological contributions from differentially expressed various angiopoietic factors may determine the clinical outcomes after preterm birth. Especially, our angiogenesis-related molecules analysis indicates that preterm birth of healthy, appropriate-for-gestational-age newborns is an “anti-angiogenic state” that may provide an increased risk for improper development and function of cardiovascular system in the adulthood. This work also contributes to a better understanding of the role of miRNAs potentially involved in angiogenesis control in preterm newborns.

Neonatal hypertension: an educational review

Hypertension is encountered in up to 3% of neonates and occurs more frequently in neonates requiring hospitalization in the neonatal intensive care unit (NICU) than in neonates in newborn nurseries or outpatient clinics. Former NICU neonates are at higher risk of hypertension secondary to invasive procedures and disease-related comorbidities. Accurate measurement of blood pressure (BP) remains challenging, but new standardized methods result in less measurement error. Multiple factors contribute to the rapidly changing BP of a neonate: gestational age, postmenstrual age (PMA), birth weight, and maternal factors are the most significant contributors. Given the natural evolution of BP as neonates mature, a percentile cutoff of 95% for PMA has been the most common definition used; however, this is not based on outcome data. Common causes of neonatal hypertension are congenital and acquired renal disease, history of umbilical arterial catheter placement, and bronchopulmonary dysplasia. The treatment of neonatal hypertension has mostly been off-label, but as evidence accumulates, the safety of medical management has increased. The prognosis of neonatal hypertension remains largely unknown and thankfully most often resolves unless secondary to renovascular disease, but further research is needed. This review discusses important factors related to neonatal hypertension including BP measurement, determinants of BP, and management of neonatal hypertension.

Postnatal inflammation following intrauterine inflammation exacerbates the development of atherosclerosis in ApoE−/− mice

Atherosclerosis is a chronic inflammatory disease that has its origins in early life. Postnatal inflammation exacerbates atherosclerosis, but the possible effect of intrauterine inflammation is largely unexplored. Exposure to inflammation in utero is common, especially in infants born preterm, who have increased cardiovascular risk in adulthood. We hypothesised that exposure to inflammation before birth would accelerate the development of atherosclerosis, with the most severe atherosclerosis following exposure to both pre- and postnatal inflammation. Here we studied the effect of prenatal and postnatal inflammation on the development of atherosclerosis by combining established techniques for modelling histological chorioamnionitis and atherosclerosis using apolipoprotein E (ApoE) knockout mice. A single intra-amniotic (IA) injection of lipopolysaccharide (LPS) caused intrauterine inflammation, and increased atherosclerosis at 13 weeks of postnatal age. In mice exposed to postnatal LPS, chorioamnionitis modulated subsequent responses; atherosclerotic lesion size, number and severity were greatest for mice exposed to both intrauterine and postnatal inflammation, with a concomitant decrease in collagen content and increased inflammation of the atherosclerotic plaque. In conclusion, pre- and postnatal inflammation have additive and deleterious effects on the development of atherosclerosis in ApoE knockout mice. The findings are particularly relevant to preterm human infants, whose gestations are frequently complicated by chorioamnionitis and who are particularly susceptible to repeated postnatal infections. Human and mechanistic studies are warranted to guide preventative strategies.

Occupational exposure to organic particles and combustion products during pregnancy and birth outcome in a nationwide cohort study in Sweden

Objective

To study if children of women exposed to organic particles and combustion products at work during pregnancy, have an increased risk of low birth weight, preterm birth or small for gestational age.

Methods

A nationwide cohort of all occupationally active mothers and their children from single births during 1994 to the end of 2012 (1 182 138 observations) was formed. Information on birth outcome was obtained from the medical birth register. Information on absence from work, education, occupation, age, nationality and smoking habits was obtained from national registers. A job exposure matrix (FINJEM) was used to assess the exposure.

Results

Pregnant women with low absence from work and high (>50th percentile) exposure to organic particles had an increased risk of giving birth to children with low birth weight (OR=1.19; 95% CI: 1.07 to 1.32), small for gestational age (OR=1.22; 95% CI: 1.07 to 1.38) or preterm birth (OR=1.17; 95% CI: 1.08 to 1.27). Subgroup analyses showed an increased risk of small for gestational age in association with exposure to oil mist. Exposure to oil mist and cooking fumes was associated with low birth weight. Paper and other organic dust was associated with preterm birth. Exposure to combustion products showed an increased risk of small for gestational age (OR=1.40; 95% CI: 1.15 to 1.71).

Conclusions

The results indicate that occupational exposure to organic particles or combustion products during pregnancy is associated with restriction of fetal growth and preterm birth. More studies are needed to confirm a casual association.

Fetal programming and the angiotensin-(1-7) axis: a review of the experimental and clinical data

Hypertension is the primary risk factor for cardiovascular disease that constitutes a serious worldwide health concern and a significant healthcare burden. As the majority of hypertension has an unknown etiology, considerable research efforts in both experimental models and human cohorts has focused on the premise that alterations in the fetal and perinatal environment are key factors in the development of hypertension in children and adults. The exact mechanisms of how fetal programming events increase the risk of hypertension and cardiovascular disease are not fully elaborated; however, the focus on alterations in the biochemical components and functional aspects of the renin-angiotensin (Ang) system (RAS) has predominated, particularly activation of the Ang-converting enzyme (ACE)-Ang II-Ang type 1 receptor (AT1R) axis. The emerging view of alternative pathways within the RAS that may functionally antagonize the Ang II axis raise the possibility that programming events also target the non-classical components of the RAS as an additional mechanism contributing to the development and progression of hypertension. In the current review, we evaluate the potential role of the ACE2-Ang-(1-7)-Mas receptor (MasR) axis of the RAS in fetal programming events and cardiovascular and renal dysfunction. Specifically, the review examines the impact of fetal programming on the Ang-(1-7) axis within the circulation, kidney, and brain such that the loss of Ang-(1-7) expression or tone, contributes to the chronic dysregulation of blood pressure (BP) and cardiometabolic disease in the offspring, as well as the influence of sex on potential programming of this pathway.

Improving pregnancy outcomes in humans through studies in sheep

Experimental studies that are relevant to human pregnancy rely on the selection of appropriate animal models as an important element in experimental design. Consideration of the strengths and weaknesses of any animal model of human disease is fundamental to effective and meaningful translation of preclinical research. Studies in sheep have made significant contributions to our understanding of the normal and abnormal development of the fetus. As a model of human pregnancy, studies in sheep have enabled scientists and clinicians to answer questions about the etiology and treatment of poor maternal, placental, and fetal health and to provide an evidence base for translation of interventions to the clinic. The aim of this review is to highlight the advances in perinatal human medicine that have been achieved following translation of research using the pregnant sheep and fetus.

Cardiac myocyte proliferation and maturation near term is inhibited by early gestation maternal testosterone exposure

Polycystic ovary syndrome is a complex and common disorder in women, and those affected experience an increased burden of cardiovascular disease. It is an intergenerational syndrome, as affected women with high androgen levels during pregnancy "program" fetal development, leading to a similar phenotype in their female offspring. The effect of excess maternal testosterone exposure on fetal cardiomyocyte growth and maturation is unknown. Pregnant ewes received biweekly injections of vehicle (control) or 100 mg testosterone propionate between 30 and 59 days of gestation (early T) or between 60 and 90 days of gestation (late T). Fetuses were delivered at ~135 days of gestation, and their hearts were enzymatically dissociated to measure cardiomyocyte growth (dimensional measurements), maturation (proportion binucleate), and proliferation (nuclear Ki-67 protein). Early T depressed serum insulin-like growth factor 1 and caused intrauterine growth restriction (IUGR; P < 0.0005). Hearts were smaller with early T ( P < 0.001) due to reduced cardiac myocyte maturation ( P < 0.0005) and proliferation ( P = 0.017). Maturation was also lower in male than female fetuses ( P = 0.004) independent of treatment. Late T did not affect cardiac growth. Early excess maternal testosterone exposure depresses circulating insulin-like growth factor 1 near term and causes IUGR in both female and male offspring. These fetuses have small, immature hearts with reduced proliferation, which may reduce cardiac myocyte endowment and predispose to adverse cardiac growth in postnatal life. While excess maternal testosterone exposure leads to polycystic ovary syndrome and cardiovascular disease in female offspring, it may also predispose to complications of IUGR and cardiovascular disease in male offspring. NEW & NOTEWORTHY Using measurements of cardiac myocyte growth and maturation in an ovine model of polycystic ovary syndrome, this study demonstrates that early gestation excess maternal testosterone exposure reduces near-term cardiomyocyte proliferation and maturation in intrauterine growth-restricted female and male fetuses. The effect of testosterone is restricted to exposure during a specific period early in pregnancy, and the effects appear mediated through reduced insulin-like growth factor 1 signaling. Furthermore, male fetuses, regardless of treatment, had fewer mature cardiomyocytes than female fetuses.

Does a maternal history of abuse before pregnancy affect pregnancy outcomes? A systematic review with meta-analysis

Background

Evidence relating maternal history of abuse before pregnancy with pregnancy outcomes is controversial. This study aims to examine the association between maternal histories of abuse before pregnancy and the risk of preterm delivery and low birth weight.

Methods

We searched Subject Headings and keywords for exposure and the outcomes through MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Psycinfo, CINAHL, Scopus, PILOTS, ProQuest Dissertations & Theses Global and Web of Science Core Collection in April 2017. We selected original studies that reported associations between maternal histories of abuse of any type and either preterm delivery or low birth weight. Studies that included interventions during pregnancy to lower maternal stress but reported no control data were excluded. We utilized the Newcastle-Ottawa Quality Assessment Scales for observational studies to assess the risk of bias in the primary studies. Two independent reviewers performed the selection of pertinent studies, assessment of risk of bias, and data extraction. Unadjusted pooled odds ratios (OR) with 95% Confidence Interval (CI) were calculated for the two outcomes of preterm delivery and low birth weight in 16 included studies.

Results

Maternal history of abuse before pregnancy was significantly associated with preterm delivery (OR 1.28, 95% CI: 1.12–1.47) and low birth weight (OR 1.35, 95% CI: 1.14–1.59). A substantial level of heterogeneity was detected within the two groups of studies reporting preterm birth and low birth weight (I² = 75% and 69% respectively). Subgroup analysis based on the specific time of abuse before pregnancy indicated that childhood abuse increases the risk of low birth weight by 57% (95% CI: 0.99–2.49). When the included studies were categorized based on study design, cohort studies showed the highest effect estimates on preterm delivery and low birth weight (OR: 1.69, 95%CI: 1.19–2.40, OR: 1.56, 95% CI: 1.06–2.3, respectively).

Conclusions

We recommend that more high quality research studies on this topic are necessary to strengthen the inference. At the practice level, we suggest more attention in detecting maternal history of abuse before pregnancy during antenatal visits and using this information to inform risk assessment for adverse pregnancy outcomes.

Trial registration

Registration number: PROSPERO (CRD42016033231).

Electronic supplementary material

The online version of this article (10.1186/s12884-018-2030-8) contains supplementary material, which is available to authorized users.

Glucocorticoids, antenatal corticosteroid therapy and fetal heart maturation

Glucocorticoids are essential in mammals to mature fetal organs and tissues in order to survive after birth. Hence, antenatal glucocorticoid treatment (termed antenatal corticosteroid therapy) can be life-saving in preterm babies and is commonly used in women at risk of preterm birth. While the effects of glucocorticoids on lung maturation have been well described, the effects on the fetal heart remain less clear. Experiments in mice have shown that endogenous glucocorticoid action is required to mature the fetal heart. However, whether the potent synthetic glucocorticoids used in antenatal corticosteroid therapy have similar maturational effects on the fetal heart is less clear. Moreover, antenatal corticosteroid therapy may increase the risk of cardiovascular disease in adulthood. Here, we present a narrative review of the evidence relating to the effects of antenatal glucocorticoid action on the fetal heart and discuss the implications for antenatal corticosteroid therapy.

Hypotension in small preterms: what does it mean?

Introduction: Small preterms often have low blood pressure readings in the first few days of life. However, what is hypotension in preterms? Should there be an aggressive approach to its management? What are the immediate and long-term side effects of powerful medications? Alternatively, could a low blood pressure be accepted instead? Materials and methods: Data were collected from files of all live babies with gestational age (GA) between 23^0/7 and 31^6/7 weeks over two different periods: years 2000-2004 and 2008-2012. Results: Our data show that, despite extremely low gestational age (ELGA)/extremely low birth weight (ELBW) neonates, almost half of these tiny babies have neither low mean arterial pressure (MAP) readings nor clinical signs of impaired perfusion. Yet, many of them are, variously treated or not, depending on individual decisions, rather than on sound evidence. Discussion: We suggest, should it be required to treat persistent hypotension, rather than treating just a low MAP recording, to address the whole issue of hypotension in the overall picture of clinical settings; we to assess organ dysfunction caused by low output and use the least aggressive measures, preferably within written protocols, tailored to the given unit, but equally, sufficiently flexible to individual babies. Furthermore, allow for "permissive hypotension" especially if transient, in the absence of clinical signs of hypoperfusion, with normal superior vena cava (SVC) flow, normal cardiac output, and normal brain scanning with normal cerebral Doppler flows. Whether treating hypotension, by whichever definition, "per se", will make any difference to both, immediate and late outcomes; in the end, treating remains open to questioning and calls for careful follow-up of these very susceptible preterms.

Neonatal hyperoxia depletes pulmonary vein cardiomyocytes in adult mice via mitochondrial oxidation

Supplemental oxygen given to preterm infants has been associated with permanently altering postnatal lung development. Now that these individuals are reaching adulthood, there is growing concern that early life oxygen exposure may also promote cardiovascular disease through poorly understood mechanisms. We previously reported that adult mice exposed to 100% oxygen between postnatal days 0 and 4 develop pulmonary hypertension, defined pathologically by capillary rarefaction, dilation of arterioles and veins, cardiac failure, and a reduced lifespan. Here, Affymetrix Gene Arrays are used to identify early transcriptional changes that take place in the lung before pulmonary capillary rarefaction. We discovered neonatal hyperoxia reduced expression of cardiac muscle genes, including those involved in contraction, calcium signaling, mitochondrial respiration, and vasodilation. Quantitative RT-PCR, immunohistochemistry, and genetic lineage mapping using Myh6^CreER; Rosa26^RmT/mG mice revealed this reflected loss of pulmonary vein cardiomyocytes. The greatest loss of cadiomyocytes was seen within the lung followed by a graded loss beginning at the hilum and extending into the left atrium. Loss of these cells was seen by 2 wk of age in mice exposed to ≥80% oxygen and was attributed, in part, to reduced proliferation. Administering mitoTEMPO, a scavenger of mitochondrial superoxide during neonatal hyperoxia prevented loss of these cells. Since pulmonary vein cardiomyocytes help pump oxygen-rich blood out of the lung, their early loss following neonatal hyperoxia may contribute to cardiovascular disease seen in these mice, and perhaps in people who were born preterm.

Moderate preterm birth affects right ventricular structure and function and pulmonary artery blood flow in adult sheep

KEY POINTS

Preterm birth occurs when the heart muscle is immature and ill-prepared for the changes in heart and lung function at birth. MRI imaging studies show differences in the growth and function of the heart of young adults born preterm, with the effects more pronounced in the right ventricle. The findings of this study, conducted in sheep, showed that following moderate preterm birth the right ventricular wall was thinner in adulthood, with a reduction in the number and size of the heart muscle cells; in addition, there was impaired blood flow in the main artery leading from the right ventricle to the lungs. The findings indicate that being born only a few weeks early adversely affects the cellular structure of the right ventricle and blood flow to the lungs in adulthood. The reduced number of heart muscle cells has the potential to deleteriously affect right ventricular growth potential and function.

ABSTRACT

Preterm birth prematurely exposes the immature heart to the haemodynamic transition at birth, which has the potential to induce abnormal cardiac remodelling. Magnetic resonance imaging studies in young adults born preterm have shown abnormalities in the gross structure of the ventricles (particularly the right ventricle; RV), but the cellular basis of these alterations is unknown. The aim of this study, conducted in sheep, was to determine the effect of moderate preterm birth on RV cellular structure and function in early adulthood. Male singleton lambs were delivered moderately preterm (132 ± 1 days; n = 7) or at term (147 ± 1 days; n = 7). At 14.5 months of age, intra-arterial blood pressure and heart rate were measured. Pulmonary artery diameter and peak systolic blood flow were determined using ultrasound imaging, and RV stroke volume and output calculated. Cardiomyocyte number, size, nuclearity and levels of cardiac fibrosis were subsequently assessed in perfusion-fixed hearts using image analysis and stereological methods. Blood pressure (systolic, diastolic and mean), heart rate, levels of myocardial fibrosis and RV stroke volume and output were not different between groups. There was, however, a significant reduction in RV wall thickness in preterm sheep, and this was accompanied by a significant reduction in peak systolic blood flow in the pulmonary artery and in RV cardiomyocyte number. Cellular changes in the RV wall and reduced pulmonary artery blood flow following preterm birth have the potential to adversely affect cardiac and respiratory haemodynamics, especially when the cardiovascular system is physiologically or pathologically challenged.

Evidence of cardiac involvement in the fetal inflammatory response syndrome: disruption of gene networks programming cardiac development in nonhuman primates

BACKGROUND

Most early preterm births are associated with intraamniotic infection and inflammation, which can lead to systemic inflammation in the fetus. The fetal inflammatory response syndrome describes elevations in the fetal interleukin-6 level, which is a marker for inflammation and fetal organ injury. An understanding of the effects of inflammation on fetal cardiac development may lead to insight into the fetal origins of adult cardiovascular disease.

OBJECTIVE

The purpose of this study was to determine whether the fetal inflammatory response syndrome is associated with disruptions in gene networks that program fetal cardiac development.

STUDY DESIGN

We obtained fetal cardiac tissue after necropsy from a well-described pregnant nonhuman primate model (pigtail macaque, Macaca nemestrina) of intrauterine infection (n=5) and controls (n=5). Cases with the fetal inflammatory response syndrome (fetal plasma interleukin-6 >11 pg/mL) were induced by either choriodecidual inoculation of a hypervirulent group B streptococcus strain (n=4) or intraamniotic inoculation of Escherichia coli (n=1). RNA and protein were extracted from fetal hearts and profiled by microarray and Luminex (Millipore, Billerica, MA) for cytokine analysis, respectively. Results were validated by quantitative reverse transcriptase polymerase chain reaction. Statistical and bioinformatics analyses included single gene analysis, gene set analysis, Ingenuity Pathway Analysis (Qiagen, Valencia, CA), and Wilcoxon rank sum.

RESULTS

Severe fetal inflammation developed in the context of intraamniotic infection and a disseminated bacterial infection in the fetus. Interleukin-6 and -8 in fetal cardiac tissues were elevated significantly in fetal inflammatory response syndrome cases vs controls (P<.05). A total of 609 probe sets were expressed differentially (>1.5-fold change, P<.05) in the fetal heart (analysis of variance). Altered expression of select genes was validated by quantitative reverse transcriptase polymerase chain reaction that included several with known functions in cardiac injury, morphogenesis, angiogenesis, and tissue remodeling (eg, angiotensin I converting enzyme 2, STEAP family member 4, natriuretic peptide A, and secreted frizzled-related protein 4; all P<.05). Multiple gene sets and pathways that are involved in cardiac morphogenesis and vasculogenesis were downregulated significantly by gene set and Ingenuity Pathway Analysis (hallmark transforming growth factor beta signaling, cellular morphogenesis during differentiation, morphology of cardiovascular system; all P<.05).

CONCLUSION

Disruption of gene networks for cardiac morphogenesis and vasculogenesis occurred in the preterm fetal heart of nonhuman primates with preterm labor, intraamniotic infection, and severe fetal inflammation. Inflammatory injury to the fetal heart in utero may contribute to the development of heart disease later in life. Development of preterm labor therapeutics must also target fetal inflammation to lessen organ injury and potential long-term effects on cardiac function.

Effects of foetal growth restriction and preterm birth on cardiac morphology and function during infancy

AIM

To investigate the effects of foetal growth restriction (FGR) and prematurity on cardiac morphology and function in infancy. We hypothesised that FGR and prematurity would both alter cardiac development.

METHODS

Cardiac morphology and function were evaluated in 24 preterm FGR infants (p-FGR) and 23 preterm and 19 term appropriately grown for gestational age infants (p-AGA and t-AGA, respectively) by conventional echocardiography and Tissue Doppler Imaging. p-FGR and p-AGA infants were studied on postnatal day 1 and all groups were studied at one-and six-months post-term age.

RESULTS

p-FGR infants demonstrated increased cardiac sphericity compared to AGA peers on postnatal day 1 (p = 0.004) and at one-month post-term age (p = 0.004). Posterior and relative wall thickness increased overtime in the p-FGR group only (p < 0.05). Systolic function was not different between groups. E/e' ratio was higher in both preterm groups compared to the term group at one-month post-term age (p = 0.01). No statistically significant group differences were found at six-months post-term age.

CONCLUSION

Foetal growth restriction was associated with subtle cardiac morphological changes, whereas both prematurity and FGR were associated with subclinical alterations in diastolic function.

Preterm Birth: Long Term Cardiovascular and Renal Consequences

BACKGROUND

Cardiovascular and chronic kidney diseases are a part of noncommunicable chronic diseases, the leading causes of premature death worldwide. They are recognized as having early origins through altered developmental programming, due to adverse environmental conditions during development. Preterm birth is such an adverse factor. Rates of preterm birth increased in the last decades, however, with the improvement in perinatal and neonatal care, a growing number of preterm born subjects has now entered adulthood. Clinical and experimental evidence suggests that preterm birth is associated with impaired or arrested structural or functional development of key organs/systems making preterm infants vulnerable to cardiovascular and chronic renal diseases at adulthood. This review analyzes the evidence of such cardiovascular and renal changes, the role of perinatal and neonatal factors such as antenatal steroids and potential pathogenic mechanisms, including developmental programming and epigenetic alterations.

CONCLUSION

Preterm born subjects are exposed to a significantly increased risk for altered cardiovascular and renal functions at young adulthood. Adequate, specific follow-up measures remain to be determined. While antenatal steroids have considerably improved preterm birth outcomes, repeated therapy should be considered with caution, as antenatal steroids induce long-term cardiovascular and metabolic alterations in animals' models and their involvement in the accelerated cellular senescence observed in human studies cannot be excluded.

Developmental programming: Interaction between prenatal BPA and postnatal overfeeding on cardiac tissue gene expression in female sheep

Epidemiologic studies and studies in rodents point to potential risks from developmental exposure to BPA on cardiometabolic diseases. Furthermore, it is becoming increasingly evident that the manifestation and severity of adverse outcomes is the result of interaction between developmental insults and the prevailing environment. Consistent with this premise, recent studies in sheep found prenatal BPA treatment prevented the adverse effects of postnatal obesity in inducing hypertension. The gene networks underlying these complex interactions are not known. mRNA-seq of myocardium was performed on four groups of four female sheep to assess the effects of prenatal BPA exposure, postnatal overfeeding and their interaction on gene transcription, pathway perturbations and functional effects. The effects of prenatal exposure to BPA, postnatal overfeeding, and prenatal BPA with postnatal overfeeding all resulted in transcriptional changes (85-141 significant differentially expressed genes). Although the effects of prenatal BPA and postnatal overfeeding did not involve dysregulation of many of the same genes, they affected a remarkably similar set of biological pathways. Furthermore, an additive or synergistic effect was not found in the combined treatment group, but rather prenatal BPA treatment led to a partial reversal of the effects of overfeeding alone. Many genes previously known to be affected by BPA and involved in obesity, hypertension, or heart disease were altered following these treatments, and AP-1, EGR1, and EGFR were key hubs affected by BPA and/or overfeeding. Environ. Mol. Mutagen. 58:4-18, 2017. © 2016 Wiley Periodicals, Inc.