Effects of maternal betamethasone administration on fetal and maternal blood pressure and heart rate in the baboon at 0.7 of gestation

Prenatal glucocorticoids exposure and adverse cardiovascular effects in offspring

Glucocorticoids (GCs) are steroid hormones fundamental to the body's normal physiological functions and are pivotal in fetal growth and development. During gestation, the mother's cortisol concentration (active GCs) escalates to accommodate the requirements of fetal organ development and maturation. A natural placental GCs barrier, primarily facilitated by 11β hydroxysteroid dehydrogenase 2, exists between the mother and fetus. This enzyme transforms biologically active cortisol into biologically inactive corticosterone, thereby mitigating fetal GCs exposure. However, during pregnancy, the mother may be vulnerable to adverse factor exposures such as stress, hypoxia, caffeine, and synthetic GCs use. In these instances, maternal serum GCs levels may surge beyond the protective capacity of the placental GCs barrier. Moreover, these adverse factors could directly compromise the placental GCs barrier, resulting in excessive fetal exposure to GCs. It is well-documented that prenatal GCs exposure can detrimentally impact the offspring's cardiovascular system, particularly in relation to blood pressure, vascular function, and heart function. In this review, we succinctly delineate the alterations in GCs levels during pregnancy and the potential mechanisms driving these changes, and also analyze the possible causes of prenatal GCs exposure. Furthermore, we summarize the current advancements in understanding the adverse effects and mechanisms of prenatal GCs exposure on the offspring's cardiovascular system.

Prenatal diagnosis and treatment for fetal angiotensin converting enzyme deficiency

OBJECTIVE

To elucidate an etiology in a case with persistent oligohydramnios by prenatal diagnosis and actively treat the case to achieve good prognosis.

METHODS

We performed whole exome sequencing (WES) of DNA from the fetus and parents. Serial amnioinfusions were conducted until birth. Pressors were required to maintain normal blood pressure. The infant angiotensin-converting enzyme (ACE) activity, angiotensin II (Ang II, a downstream product of ACE), and compensatory enzymes (CEs) activities were measured. Compensatory enzyme activities in plasma from age-matched healthy controls were also detected.

RESULTS

We identified a fetus with a severe ACE mutation prenatally. The infant was born prematurely without pulmonary dysplasia. Hypotension and anuria resolved spontaneously. He had almost no ACE activity, but his Ang II level and CE activity exceeded the upper limit of the normal range and the upper limit of the 95% confidence interval of controls, respectively. His renal function also largely recovered.

CONCLUSION

Fetuses with ACE mutations can be diagnosed prenatally through WES. Serial amnioinfusion permits the continuation of pregnancy in fetal ACE deficiency. Compensatory enzymes for defective ACE appeared postnatally. Renal function may be spared by preterm delivery; furthermore, for postnatal vasopressor therapy to begin, improving renal perfusion pressure before nephrogenesis has been completed.

Changes in Maternal Heart Rate and Autonomic Regulation following the Antenatal Administration of Corticosteroids: A Secondary Analysis

While the effect of antenatally administered corticosteroids on fetal heart rate (HR) and heart rate variability (HRV) is well established, little information is available on how these drugs affect maternal physiology. In this secondary analysis of a prospective, observational cohort study, we quantify how corticosteroids affect maternal HR and HRV, which serve as a proxy measure for autonomic regulation. Abdominal ECG measurements were recorded before and in the five days following the administration of betamethasone—a corticosteroid commonly used for fetal maturation—in 46 women with singleton pregnancies. Maternal HR and HRV were determined from these recordings and compared between these days. HRV was assessed with time- and frequency-domain features, as well as non-linear and complexity features. In the 24 h after betamethasone administration, maternal HR was significantly increased (p < 0.01) by approximately 10 beats per minute, while HRV features linked to parasympathetic activity and HR complexity were significantly decreased (p < 0.01 and p < 0.001, respectively). Within four days after the initial administration of betamethasone, HR decreases and HRV features increase again, indicating a diminishing effect of betamethasone a few days after administration. We conclude that betamethasone administration results in changes in maternal HR and HRV, despite the heterogeneity of the studied population. Therefore, its recent administration should be considered when evaluating these cardiovascular metrics.

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.

Changes in Maternal Heart Rate Variability in Response to the Administration of Routine Obstetric Medication in Hospitalized Patients: Study Protocol for a Cohort Study (MAMA-Heart Study)

Pregnancy is a period of continuous change in the maternal cardiovascular system, partly mediated by the autonomic nervous system. Insufficient autonomic adaptation to increasing gestation is associated with pregnancy complications, such as hypertensive disorders of pregnancy and preterm birth (both major causes of perinatal morbidity and mortality). Consequently, maternal heart rate variability (mHRV), which is a proxy measure for autonomic activity, is increasingly assessed in these cohorts to investigate the pathophysiology of their complications. A better pathophysiological understanding could facilitate the early detection of these complications, which remains challenging. However, such studies (typically performed in pregnancies leading to hospitalization) have generated conflicting findings. A probable reason for these conflicting findings is that these study cohorts were likely administered routine obstetric medications during the study period of which the effects on mHRV are largely unknown. Subsequently, we design a longitudinal, observational study to quantifying the effect of these medications-particularly corticosteroids, which are known to affect fetal HRV-on mHRV to improve the interpretation of past and future studies. We will enroll 61 women admitted to a tertiary obstetric unit with an indication to receive corticosteroids antenatally. Participants' mHRV will be continuously acquired throughout their hospitalization with wrist-worn photoplethysmography to facilitate a within-patient comparison of the effect of corticosteroids on mHRV.

The nonhuman primate hypothalamo-pituitary-adrenal axis is an orchestrator of programming-aging interactions: role of nutrition

Developmental programming alters life-course multi-organ function and significantly affects life-course health. Recently, interest has developed in how programming may influence the rate of aging. This review describes interactions of nutrition and programming-aging interactions in hypothalamo-pituitary-adrenal (HPA) development and function from fetal development to old age. A full picture of these interactions requires data on levels of HPA activity relating to the hypothalamic, adrenal cortical, circulating blood, and peripheral cortisol metabolism. Data are provided from studies on our baboon, nonhuman primate model both across the normal life course and in offspring of maternal baboons who were moderately undernourished by a global 30% diet reduction during pregnancy and lactation. Sex differences in offspring outcomes in response to similar challenges are described. The data clearly show programming of increased HPA axis activity by moderate maternal undernutrition. Increased postnatal circulating cortisol concentrations are related to accelerated aging of the brain and cardiovascular systems. Future studies should address peripheral cortisol production and the influence of aging advantage in females. These data support the view that the HPA is an orchestrator of interactions of programming-aging mechanisms.

Glucocorticoid Maturation of Fetal Cardiovascular Function

The last decade has seen rapid advances in the understanding of the central role of glucocorticoids in preparing the fetus for life after birth. However, relative to other organ systems, maturation by glucocorticoids of the fetal cardiovascular system has been ignored. Here, we review the effects of glucocorticoids on fetal basal cardiovascular function and on the fetal cardiovascular defense responses to acute stress. This is important because glucocorticoid-driven maturational changes in fetal cardiovascular function under basal and stressful conditions are central to the successful transition from intra- to extrauterine life. The cost-benefit balance for the cardiovascular health of the preterm baby of antenatal glucocorticoid therapy administered to pregnant women threatened with preterm birth is also discussed.

Cardiovascular effects of prenatal stress-Are there implications for cerebrovascular, cognitive and mental health outcome?

Prenatal stress programs offspring cognitive and mental health outcome. We reviewed whether prenatal stress also programs cardiovascular dysfunction which potentially modulates cerebrovascular, cognitive and mental health disorders. We focused on maternal stress and prenatal glucocorticoid (GC) exposure which have different programming effects. While maternal stress induced cortisol is mostly inactivated by the placenta, synthetic GCs freely cross the placenta and have different receptor-binding characteristics. Maternal stress, particularly anxiety, but not GC exposure, has adverse effects on maternal-fetal circulation throughout pregnancy, probably by co-activation of the maternal sympathetic nervous system, and by raising fetal catecholamines. Both effects may impair neurodevelopment. Experimental data also suggest that severe maternal stress and GC exposure during early and mid-gestation may increase the risk for cardiovascular disorders. Human data are scarce and especially lacking for older age. Programming mechanisms include aberrations in cardiac and kidney development, and functional changes in the renin-angiotensin-aldosterone-system, stress axis and peripheral and coronary vasculature. Adequate experimental or human studies examining the consequences for cerebrovascular, cognitive and mental disorders are unavailable.

Antenatal Synthetic Glucocorticoid Exposure at Human Therapeutic Equivalent Doses Predisposes Middle-Age Male Offspring Baboons to an Obese Phenotype That Emerges With Aging

INTRODUCTION

Women threatening premature delivery receive synthetic glucocorticoids (sGC) to accelerate fetal lung maturation, reducing neonatal mortality and morbidity. Few investigations have explored potential long-term offspring side effects. We previously reported increased pericardial fat and liver lipids in 10-year-old (human equivalent 40 years) male baboons exposed to 3 antenatal sGC courses. We hypothesized middle-aged sGC male offspring show obesity-related morphometric changes.

METHODS

Pregnant baboons received courses of 2 betamethasone injections (175 μg·kg-1·d-1 intramuscular) at 0.6, 0.64, and 0.68 gestation. At 10 to 12.5 years, we measured morphometrics and serum lipids in 5 sGC-exposed males and 10 age-matched controls. We determined whether morphometric parameters predicted amount of pericardial fat or lipids. Life-course serum lipids were measured in 25 males (7-23 years) providing normal regression formulas to compare sGC baboons' lipid biological and chronological age.

RESULTS

Birth weights were similar. When studied, sGC-exposed males showed a steeper weight increase from 8 to 12 years and had increased waist and hip circumferences, neck and triceps skinfolds, and total and low-density lipoprotein cholesterol. Triceps skinfold correlated with apical and midventricular pericardial fat thickness, hip and waist circumferences with insulin.

CONCLUSIONS

Triceps skinfold and waist and hip circumferences are useful biomarkers for identifying individuals at risk for obesity and metabolic dysregulation following fetal sGC exposure. Prenatal sGC exposure predisposes male offspring to internal adiposity, greater body size, and increased serum lipids. Results provide further evidence for developmental programming by fetal sGC exposure and call attention to potential emergence of adverse life-course effects.

The Effect of Antenatal Betamethasone on White Matter Inflammation and Injury in Fetal Sheep and Ventilated Preterm Lambs

Antenatal administration of betamethasone (BM) is a common antecedent of preterm birth, but there is limited information about its impact on the acute evolution of preterm neonatal brain injury. We aimed to compare the effects of maternal BM in combination with mechanical ventilation on the white matter (WM) of late preterm sheep. At 0.85 of gestation, pregnant ewes were randomly assigned to receive intra-muscular (i.m.) saline (n = 9) or i.m. BM (n = 13). Lambs were delivered and unventilated controls (UVCSal, n = 4; UVCBM, n = 6) were humanely killed without intervention; ventilated lambs (VentSal, n = 5; VentBM, n = 7) were injuriously ventilated for 15 min, followed by conventional ventilation for 75 min. Cardiovascular and cerebral haemodynamics and oxygenation were measured continuously. The cerebral WM underwent assessment of inflammation and injury, and oxidative stress was measured in the cerebrospinal fluid (CSF). In the periventricular and subcortical WM tracts, the proportion of amoeboid (activated) microglia, the density of astrocytes, and the number of blood vessels with protein extravasation were higher in UVCBM than in UVCSal (p < 0.05 for all). During ventilation, tidal volume, mean arterial pressure, carotid blood flow, and oxygen delivery were higher in -VentBM lambs (p < 0.05 vs. VentSal). In the subcortical WM, microglial infiltration was increased in the VentSal group compared to UVCSal. The proportion of activated microglia and protein extravasation was higher in the VentBM group compared to VentSal within the periventricular and subcortical WM tracts (p < 0.05). CSF oxidative stress was increased in the VentBM group compared to UVCSal, UVCBM, and VentSal groups (p < 0.05). Antenatal BM was associated with inflammation and vascular permeability in the WM of late preterm fetal sheep. During the immediate neonatal period, the increased carotid perfusion and oxygen delivery in BM-treated lambs was associated with increased oxidative stress, microglial activation and microvascular injury.

Postnatal cardiovascular adaptation

The heart undergoes rapid transformations in function during the transition to extrauterine life. Our understanding of the adaptive physiology underlying this process is able to inform the clinical management of infants who are struggling to complete this complex transition. Much of our knowledge of the cardiac transition is derived from the preterm infant in whom the preparative adaptations are incomplete and clinical sequelae all too common. This review will re-examine the cardiac transition highlighting the physiology that drives it and suggest appropriate clinical intervention to support the process.

Efficacy and safety of antenatal steroids

Antenatal steroids (ANS) are among the most important and widely utilized interventions to improve outcomes for preterm infants. A significant body of evidence demonstrates improved outcomes in preterm infants (24-34 wk) delivered between 1 and 7 days after the administration of a single course of ANS. Moreover, ANS have the advantage of being widely available, low cost, and easily administered via maternal intramuscular injection. The use of ANS to mature the fetal lung is, however, not without contention. Their use in pregnancy is not FDA approved, and treatment doses and regimens remain largely unoptimized. Their mode of use varies considerably between countries, and there are lingering concerns regarding the safety of exposing the fetus to high doses of exogenous steroids. A significant proportion of women deliver outside the 1- to 7-day therapeutic window after ANS treatment, and this delay may be associated with an increased risk of adverse outcomes for both mother and baby. Today, animal-based studies are one means by which key questions of dosing and safety relating to ANS may be resolved, allowing for further refinement(s) of this important therapy. Complementary approaches using nonhuman primates, sheep, and rodents have provided invaluable advances to our understanding of how exogenous steroid exposure impacts fetal development. Focusing on these three major model groups, this review highlights the role of three key animal models (sheep, nonhuman primates, rodents) in the development of antenatal steroid therapy, and provides an up-to-date synthesis of current efforts to refine this therapy in an era of personalised medicine.

A decline in female baboon hypothalamo-pituitary-adrenal axis activity anticipates aging

Stressors that disrupt homeostasis advance aging. Glucocorticoids regulate multiple processes that determine the aging trajectory. Debate exists regarding life-course circulating glucocorticoid concentrations. Rodent and nonhuman primate studies indicate circulating glucocorticoids fall from early life. We measured fasting morning cortisol in 24 female baboons (6-21 years, human equivalent ~18-70). We also quantified hypothalamic paraventricular nuclear (PVN) arginine vasopressin (AVP), corticotropin-releasing hormone, steroid receptors, and pituitary proopiomelanocortin immunohistochemically in 14 of these females at 6-13 years. We identified significant age-related 1) linear fall in cortisol and PVN AVP from as early as 6 years; 2) increased PVN glucocorticoid and mineralocorticoid receptors; 3) increased PVN 11β-hydroxysteroid dehydrogenase 1 and 2, regulators of local cortisol production, and 4) decreased pituitary proopiomelanocortin. Our data identify increased age-related negative feedback and local PVN cortisol production as potential mechanisms decreasing PVN drive to hypothalamo-pituitary-adrenal axis activity that result in the age-related circulating cortisol fall. Further studies are needed to determine whether the cortisol fall 1) causes aging, 2) protects by slowing aging, or 3) is an epiphenomenon unrelated to aging processes. We conclude that aging processes are best studied by linear life-course analysis beginning early in life.

Fetal heart rate variation after corticosteroids for fetal maturation

INTRODUCTION

Several studies report a decrease of fetal heart rate (FHR) short-term variation (STV) after corticosteroids for improvement of fetal maturity and advice not to deliver a fetus for low STV within 2-3days after corticosteroids. However, literature is not unanimous in this respect. This study intends to asses STV longitudinally after corticosteroid administration.

MATERIAL AND METHODS

A retrospective cohort study in a tertiary perinatal centre from 2009 to 2015 included all women who had been treated with corticosteroids at gestational age of 26-34 weeks, had a computerized cardiotocography (cCTG) before and after medication and did not deliver within 48h. FHR and STV were stratified over 12-h periods and compared before and after corticosteroids. Women with imminent preterm labour (including PPROM) and women with placental problems (fetal growth restriction (FGR) or preeclampsia) (PE) were analysed separately. The effect of co-medication and gestational age was assessed.

RESULTS

The study included 406 women, 211 with imminent preterm labour, 195 with FGR-PE. After corticosteroids STV increased 1-2ms (median 1.4; IQR 0.1-3.1) during the first 36h after start of corticosteroids. Thereafter a small decrease of less than 1ms (median -0,6; IQR -1.6 to 0.3) compared to before CC was seen.

CONCLUSIONS

The most conspicuous effect of corticosteroids is a short term increase of STV and decrease of FHR. A slight decrease after 48-71h is possible, but abnormally low values should be considered as a sign of fetal distress. The clinical guidance, given by some, not to intervene because of a low STV after corticosteroids appears invalid.

Longitudinal progression of fetal short-term variation and average acceleration and deceleration capacity after antenatal maternal betamethasone application

OBJECTIVE

To analyze the effect of maternal betamethasone given for fetal lung maturation on fetal short-term variation (STV) and average acceleration and deceleration capacity (AAC/ADC). Both of these factors are calculated by phase-rectified signal averaging (PRSA) and represent new parameters to assess the fetal autonomic nervous system.

STUDY DESIGN

A longitudinal prospective study including 26 pregnant women at risk for preterm delivery was performed. Two injections of 12mg betamethasone were administered intramuscularly at a 24h interval for lung maturation. Cardiotocography recordings were performed at defined time intervals: day 0 (before the first injection) and days 1, 2, 4 after the first corticosteroid administration. AAC/ADC and STV were calculated.

RESULTS

An increase of all parameters (STV, AAC and ADC) was documented between day 0 and day 1. Between day 1 and day 2, all three indices were significantly reduced (p<0.05). STV declined by 19.8%, AAC by 10.1% and ADC by 14.8%. A normalization of these values was seen after 96h.

CONCLUSION

Similar to STV, AAC/ADC shows significant changes after maternal betamethasone administration. The corticosteroid-induced transient decrease of the levels needs to be taken into account in the assessment of the fetal status to avoid misinterpretation of these parameters.

In Utero Origins of Hypertension: Mechanisms and Targets for Therapy

The developmental origins of health and disease theory is based on evidence that a suboptimal environment during fetal and neonatal development can significantly impact the evolution of adult-onset disease. Abundant evidence exists that a compromised prenatal (and early postnatal) environment leads to an increased risk of hypertension later in life. Hypertension is a silent, chronic, and progressive disease defined by elevated blood pressure (>140/90 mmHg) and is strongly correlated with cardiovascular morbidity/mortality. The pathophysiological mechanisms, however, are complex and poorly understood, and hypertension continues to be one of the most resilient health problems in modern society. Research into the programming of hypertension has proposed pharmacological treatment strategies to reverse and/or prevent disease. In addition, modifications to the lifestyle of pregnant women might impart far-reaching benefits to the health of their children. As more information is discovered, more successful management of hypertension can be expected to follow; however, while pregnancy complications such as fetal growth restriction, preeclampsia, preterm birth, etc., continue to occur, their offspring will be at increased risk for hypertension. This article reviews the current knowledge surrounding the developmental origins of hypertension, with a focus on mechanistic pathways and targets for therapeutic and pharmacologic interventions.

Measurement of betamethasone concentration in maternal serum treated for fetal lung maturity; Is it feasible?

BACKGROUND

The association between maternal serum concentration of betamethasone given for fetal lung maturity and perinatal outcome has not been investigated. This may be due to an absence of a reliable method for measuring serum betamethasone concentrations. We aimed in the current study to assess the feasibility of a specific ELISA kit to measure the concentrations of betamethasone in maternal serum and to examine the trend of sequential measurements after a course of betamethasone for fetal lung maturity.

METHODS

Pregnant women at risk for preterm birth who received betamethasone between 24 and 34 weeks of gestation were prospectively included. Serum concentrations were determined before administering betamethasone (baseline), and 36 hours, 48 hours, 72 hours, and 5 to 7 days after the 1(st) dose. Betamethasone concentration in samples was determined using Corticosteroid ELISA kit. The Friedman test was used to test whether there were significant differences between the measurements.

RESULTS

Five singleton pregnancies were included. Using the ELISA kit, betamethasone concentration in maternal serum samples was obtained for all women. Among the five measurements performed, the concentration was highest at 36 hours after the 1(st) dose and close to baseline at the 5(th) measurement performed after 5 to 7 days (p < 0.05). Serum concentration varied at each time point between the five women but similar trend was observed.

CONCLUSION

Betamethasone concentration is measurable in the serum of pregnant women with this ELISA kit.

Comparison of effects of nifedipine and ritodrine on maternal and fetal blood flow patterns in preterm labor

OBJECTIVE

The aim of this study was to investigate and compare the effects of nifedipine and ritodrine treatment on fetomaternal blood flow parameters in women with preterm labor.

MATERIAL AND METHODS

Sixty women with gestational age between 24 and 36 weeks admitted to the obstetrics clinic for preterm labor were enrolled in this study. Patients were randomly assigned to receive either nifedipine (n=30) or ritodrine (n=30) treatment. Demographic features, clinic and laboratory parameters, fetal and maternal side effects, and Doppler ultrasound indices of the umbilical artery (UA), uterine arteries (UtA), and middle cerebral artery (MCA) before, 2 hours after, and 48 hours after the initiation of tocolytic treatments were compared between the two groups.

RESULTS

In both the groups, early- and late-onset changes in the pulsatility index (PI) and other Doppler indices for UA, UtA, and MCA were similar. In addition, time elapsed till delivery, fetal mortality, and maternal morbidity in both the groups were not statistically significant (p>0.05). However, maternal side effects such as tachycardia was more frequent (p<0.05) in the ritodrine group. Besides, in the ritodrine group, anxiety was only minimally observed.

CONCLUSION

Nifedipine and ritodrine used as tocolytic agents did not significantly alter early- and late-onset changes in Doppler ultrasonography parameters in fetal and fetomaternal circulation.

The effects of antenatal corticosteroids therapy on very preterm infants after chorioamnionitis

PURPOSE

To evaluate the effectiveness of antenatal corticosteroids (AC) therapy on outcomes of very low birthweight infants with histologic chorioamnionitis.

METHODS

We performed a retrospective analysis of 10,935 single infants born at a gestational age between 22 + 0 and 33 + 6 weeks and birth weight <1,500 g. Clinical data were obtained from the Neonatal Research Network that included the tertiary neonatal intensive care units throughout Japan between 2003 and 2008.

RESULTS

Data of 7,896 infants were available for the period 2003-2008 and were included in the analysis. According to logistic regression analysis, AC were significantly associated with reduced mortality [odds ratio (OR) = 0.50; p < 0.001], lower incidence of respiratory distress syndrome (OR = 0.72; p < 0.001), neonatal seizure (OR = 0.65; p = 0.003) and intraventricular hemorrhage (OR = 0.68; p = 0.001) in cases after histologic chorioamnionitis compared with the cases had no AC therapy (n = 3,271 vs. 4,625). Antenatal corticosteroids were significantly associated with reduced mortality [odds ratio (OR) = 0.60; p < 0.001] among the cases without histologic chorioamnionitis.

CONCLUSION

In the retrospective population-based study in Japan, AC exposure was significantly associated with a lower rate of death and neurological morbidity in cases with histologic chorioamnionitis. These outcome data in Japan will be important for further improvement of antenatal practice and care.

Effects of maternal nutrient restriction, intrauterine growth restriction, and glucocorticoid exposure on phosphoenolpyruvate carboxykinase-1 expression in fetal baboon hepatocytes in vitro

BACKGROUND

The objective of this study was to develop a cell culture system for fetal baboon hepatocytes and to test the hypotheses that (i) expression of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase-1 (PEPCK-1) is upregulated in hepatocytes isolated from fetuses of nutrient-restricted mothers (MNR) compared with ad libitum-fed controls (CTR), and (ii) glucocorticoids stimulate PEPCK-1 expression.

METHODS

Hepatocytes from 0.9G CTR and MNR fetuses were isolated and cultured. PEPCK-1 protein and mRNA levels in hepatocytes were determined by Western blot and quantitative PCR, respectively.

RESULTS

Fetuses of MNR mothers were intrauterine growth restricted (IUGR). Feasibility of culturing 0.9G fetal baboon hepatocytes was demonstrated. PEPCK-1 protein levels were increased in hepatocytes isolated from IUGR fetuses, and PEPCK-1 mRNA expression was stimulated by glucocorticoids in fetal hepatocytes.

CONCLUSIONS

Cultured fetal baboon hepatocytes that retain their in vivo phenotype provide powerful in vitro tools to investigate mechanisms that regulate normal and programmed hepatic function.

Glucocorticoid programming of the fetal male hippocampal epigenome

The late-gestation surge in fetal plasma cortisol is critical for maturation of fetal organ systems. As a result, synthetic glucocorticoids (sGCs) are administered to pregnant women at risk of delivering preterm. However, animal studies have shown that fetal exposure to sGC results in increased risk of behavioral, endocrine, and metabolic abnormalities in offspring. Here, we test the hypothesis that prenatal GC exposure resulting from the fetal cortisol surge or after sGC exposure results in promoter-specific epigenetic changes in the hippocampus. Fetal guinea pig hippocampi were collected before (gestational day [GD52]) and after (GD65) the fetal plasma cortisol surge (Term∼GD67) and 24 hours after (GD52) and 14 days after (GD65) two repeat courses of maternal sGC (betamethasone) treatment (n = 3-4/gp). We identified extensive genome-wide alterations in promoter methylation in late fetal development (coincident with the fetal cortisol surge), whereby the majority of the affected promoters exhibited hypomethylation. Fetuses exposed to sGC in late gestation exhibited substantial differences in DNA methylation and histone h3 lysine 9 (H3K9) acetylation in specific gene promoters; 24 hours after the sGC treatment, the majority of genes affected were hypomethylated or hyperacetylated. However, 14 days after sGC exposure these differences did not persist, whereas other promoters became hypermethylated or hyperacetylated. These data support the hypothesis that the fetal GC surge is responsible, in part, for significant variations in genome-wide promoter methylation and that prenatal sGC treatment profoundly changes the epigenetic landscape, affecting both DNA methylation and H3K9 acetylation. This is important given the widespread use of sGC in the management of women in preterm labor.

Glucocorticoids as mediators of developmental programming effects

Epidemiological evidence suggests that exposure to an adverse environment in early life is associated with an increased risk of cardio-metabolic and behavioral disorders in adulthood, a phenomenon termed 'early life programming'. One major hypothesis for early life programming is fetal glucocorticoid overexposure. In animal studies, prenatal glucocorticoid excess as a consequence of maternal stress or through exogenous administration to the mother or fetus is associated with programming effects on cardiovascular and metabolic systems and on the brain. These effects can be transmitted to subsequent generations. Studies in humans provide some evidence that prenatal glucocorticoid exposure may exert similar programming effects on glucose/insulin homeostasis, blood pressure and neurodevelopment. The mechanisms by which glucocorticoids mediate these effects are unclear but may include a role for epigenetic modifications. This review discusses the evidence for glucocorticoid programming in animal models and in humans.

Fetal stress and programming of hypoxic/ischemic-sensitive phenotype in the neonatal brain: mechanisms and possible interventions

Growing evidence of epidemiological, clinical and experimental studies has clearly shown a close link between adverse in utero environment and the increased risk of neurological, psychological and psychiatric disorders in later life. Fetal stresses, such as hypoxia, malnutrition, and fetal exposure to nicotine, alcohol, cocaine and glucocorticoids may directly or indirectly act at cellular and molecular levels to alter the brain development and result in programming of heightened brain vulnerability to hypoxic-ischemic encephalopathy and the development of neurological diseases in the postnatal life. The underlying mechanisms are not well understood. However, glucocorticoids may play a crucial role in epigenetic programming of neurological disorders of fetal origins. This review summarizes the recent studies about the effects of fetal stress on the abnormal brain development, focusing on the cellular, molecular and epigenetic mechanisms and highlighting the central effects of glucocorticoids on programming of hypoxic-ischemic-sensitive phenotype in the neonatal brain, which may enhance the understanding of brain pathophysiology resulting from fetal stress and help explore potential targets of timely diagnosis, prevention and intervention in neonatal hypoxic-ischemic encephalopathy and other brain disorders.

Sex-dependent cognitive performance in baboon offspring following maternal caloric restriction in pregnancy and lactation

In humans a suboptimal diet during development has negative outcomes in offspring. We investigated the behavioral outcomes in baboons born to mothers undergoing moderate maternal nutrient restriction (MNR). Maternal nutrient restriction mothers (n = 7) were fed 70% of food eaten by controls (CTR, n = 12) fed ad libitum throughout gestation and lactation. At 3.3 ± 0.2 (mean ± standard error of the mean [SEM]) years of age offspring (controls: female [FC, n = 8], male [MC, n = 4]; nutrient restricted: female [FR, n = 3] and male [MR, n = 4]) were administered progressive ratio, simple discrimination, intra-/extra-dimension set shift and delayed matching to sample tasks to assess motivation, learning, attention, and working memory, respectively. A treatment effect was observed in MNR offspring who demonstrated less motivation and impaired working memory. Nutrient-restricted female offspring showed improved learning, while MR offspring showed impaired learning and attentional set shifting and increased impulsivity. In summary, 30% restriction in maternal caloric intake has long lasting neurobehavioral outcomes in adolescent male baboon offspring.

Potential risks and benefits of antenatal corticosteroid therapy prior to preterm birth in pregnancies complicated by severe fetal growth restriction

The antepartum administration of fluorinated corticosteroids for fetal maturation represents the most important clinical contribution in the battle against prematurity. This treatment reduces the risk of neonatal death and handicap. It is also known that on corticosteroid exposure, fetuses are subjected to transiently increased physiologic and metabolic demands. Healthy fetuses are able to cope, although emerging evidence suggests this may not be the case with severely growth-restricted fetuses. This review presents evidence of efficacy and safety pertaining to corticosteroid administration in fetal growth restriction–affected pregnancies, offers guidance to clinicians, and points out questions that still need answers.

Preterm birth and the kidney: implications for long-term renal health

Although the majority of preterm neonates now survive infancy, there is emerging epidemiological evidence to demonstrate that individuals born preterm exhibit an elevated risk for the development of hypertension and renal impairment later in life, thus supporting the developmental origins of health and disease hypothesis. The increased risk may potentially be attributed to a negative impact of preterm birth on nephron endowment. Indeed, at the time when most preterm neonates are delivered, nephrogenesis in the kidney is still ongoing with the majority of nephrons normally formed during the third trimester of pregnancy. A number of clinical studies have provided evidence of altered renal function during the neonatal period, but to date there have been limited studies describing the consequences of preterm birth on kidney structure. Importantly, studies in the preterm baboon have shown that nephrogenesis is clearly ongoing following preterm birth; however, the presence of abnormal glomeruli (up to 18% in some cases) is of concern. Similar glomerular abnormalities have been described in autopsied preterm infants. Prenatal and postnatal factors such as exposure to certain medications, hyperoxia and intrauterine and/or extrauterine growth restriction are likely to have a significant influence on nephrogenesis and final nephron endowment. Further studies are required to determine the factors contributing to renal maldevelopment and to identify potential interventional strategies to maximize nephron endowment at the start of life, thereby optimizing long-term renal health for preterm individuals.

Emergence of insulin resistance in juvenile baboon offspring of mothers exposed to moderate maternal nutrient reduction

Developmental programming of postnatal pancreatic β-cell and peripheral insulin function by maternal nutrient reduction (MNR) has been extensively investigated in rodents and sheep, but no data exist from nonhuman primate offspring of MNR mothers. We hypothesized that moderate levels of MNR would result in developmental programming of postnatal β-cell function and peripheral insulin sensitivity that lead to emergence of a prediabetic state prior to puberty. Prepregnancy phenotype of 18 nonpregnant baboons was matched. During pregnancy and lactation 12 mothers ate chow ad libitum (controls), while six ate 70% of chow consumed by controls (weight-adjusted MNR). Weaned offspring ate normal chow. At 3.5 ± 0.18 yr (mean ± SE) in an intravenous glucose tolerance test, conscious, tethered MNR juvenile offspring (2 females and 4 males) showed increased fasting glucose (P < 0.04), fasting insulin (P < 0.04), and insulin area under the curve (AUC; P < 0.01) compared with controls (8 females and 4 males). Insulin AUC also increased following an arginine challenge (P < 0.02). Baseline homeostatic model assessment insulin β-cell sensitivity was greater in MNR offspring than controls (P < 0.03). In a hyperinsulinemic, euglycemic clamp, the glucose disposal rate decreased 26% in MNR offspring. Changes observed were not sex dependent. MNR in pregnancy and lactation programs offspring metabolic responses, increasing insulin resistance and β-cell responsiveness, resulting in emergence of an overall phenotype that would predispose to later life type-2 diabetes, especially, should other dietary challenges such as a Westernized diet be experienced.

Prenatal overexposure to glucocorticoids programs renal 11β-hydroxysteroid dehydrogenase type 2 expression and salt-sensitive hypertension in the rat

OBJECTIVE

Prenatal glucocorticoid excess programs hypertension in adulthood. The underlying mechanisms are unknown. Here, we tested whether hypertension in this model is due to increased renal mineralocorticoid activity.

METHODS

Pregnant rats were injected daily with the synthetic glucocorticoid dexamethasone (DEX) or vehicle during the last week of pregnancy. Blood pressure, electrolytes and target gene expression were measured in the offspring.

RESULTS

Adult DEX-treated offspring were hypertensive (SBP, 140.1 ± 2.4 vs. 128.6 ± 3.2 mmHg; P = 0.009), hypokalemic (4.5 ± 0.2 vs. 5.1 ± 0.2 mmol/l; P = 0.03) and had suppressed plasma renin concentration (23.6 ± 4.8 vs. 43.8 ± 5.9 ng/ml; P = 0.017). DEX programming had similar effects in younger rats (age 2 months), but only when fed a high-salt diet. Although these data are consistent with excess mineralocorticoid activity, plasma aldosterone levels were unaffected and daily urinary aldosterone values were decreased (136.1 ± 27.0 vs. 303.6 ± 47.0 ng/kg; P = 0.008). Accordingly, we assessed renal factors that might influence mineralocorticoid responsiveness. Renal expression of mineralocorticoid receptor and glucocorticoid receptor mRNAs was unaltered, as was 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) which regenerates active glucocorticoids. However, renal mRNA for 11β-HSD2, which catalyses inactivation of glucocorticoids in the distal nephron and thus protects mineralocorticoids from glucocorticoids, was decreased by 45% in both new born and adult rats (P < 0.01). The functional significance of this reduction was confirmed by measurements of renal 11β-HSD activity and by demonstrating that the mineralocorticoid properties of cortisol were enhanced in DEX-programmed rats. Additionally, the difference in blood pressure between DEX and control groups was abolished upon administration of spironolactone, a mineralocorticoid receptor antagonist.

CONCLUSION

The blood pressure phenotype of DEX-programmed rats may in part be explained by a life-long reduction in renal 11β-HSD2 activity. Salt-sensitive hypertension could be programmed by prenatal stress.

Effect of antenatal betamethasone administration on neonatal cardiac autonomic balance

Beneficial effects of antenatal glucocorticoid treatment in pregnancies at risk for preterm delivery may entail long-term consequences for the establishment of sympathoadrenergic system balance. We analyzed the cardiac autonomic system activity in neonates with a single course of antenatal betamethasone (2 × 12 mg) treatment by calculating heart rate variability (HRV) time-domain parameters from 24 h ECG recordings and short-term frequency-domain parameters during infant active and resting states. In addition, resting and challenged salivary α-amylase levels were measured in 23 betamethasone-exposed neonates and compared with controls. Indicators for overall HRV (SDNN: p = 0.258; triangular index: p = 0.179) and sympathovagal balance [low- to high-frequency power (LF/HF): p = 0.82 (resting state)] were not significantly different in neonates of the betamethasone treatment group. Parameters mostly influenced by sympathetic activity [SD of the average of valid NN intervals (SDANN): p = 0.184 and SDs of all NN intervals (SDNNi): p = 0.784] and vagal tone [RMSSD: p = 1.0; NN50: p = 0.852; HF: p = 0.785 (resting state)] were unaltered. Resting α-amylase levels were not significantly different in the betamethasone treatment group (p = 0.304); however, α-amylase release after a neonatal challenge was slightly reduced (p = 0.045). Thus, cardiac autonomic balance seems to be preserved in neonates exposed to a single course of antenatal betamethasone treatment.

Epigenetic modification of fetal baboon hepatic phosphoenolpyruvate carboxykinase following exposure to moderately reduced nutrient availability

Decreased maternal nutrient availability during pregnancy induces compensatory fetal metabolic and endocrine responses. Knowledge of cellular changes involved is critical to understanding normal and abnormal development. Several studies in rodents and sheep report increased fetal plasma cortisol and associated increased gluconeogenesis in response to maternal nutrient reduction (MNR) but observations in primates are lacking. We determined MNR effects on fetal liver phosphoenolpyruvate carboxykinase 1 (protein, PEPCK1; gene, PCK1 orthologous/homologous human chromosomal region 20q13.31) at 0.9 gestation (G). Female baboon social groups were fed ad libitum (control, CTR) or 70% CTR (MNR) from 0.16 to 0.9G when fetuses were delivered by caesarean section under general anaesthesia. Plasma cortisol was elevated in fetuses of MNR mothers (P < 0.05). Immunoreactive PEPCK1 protein was located around the liver lobule central vein and was low in CTR fetuses but rose to 63% of adult levels in MNR fetuses. PCK1 mRNA measured by QRT-PCR increased in MNR (2.3-fold; P < 0.05) while the 25% rise in protein by Western blot analysis was not significant. PCK1 promoter methylation analysis using bisulfite sequencing was significantly reduced in six out of nine CpG-dinucleotides evaluated in MNR compared with CTR liver samples. In conclusion, these are the first data from a fetal non-human primate indicating hypomethylation of the PCK1 promoter in the liver following moderate maternal nutrient reduction.

Dose-response effects of betamethasone on maturation of the fetal sheep lung

OBJECTIVE

Glucocorticoid administration to women in preterm labor improves neonatal mortality and morbidity. Fetal exposure to glucocorticoid levels higher than those appropriate to the current gestational stage has multiple organ system effects. Some, eg, fetal hypertension, are maximal at lower than the clinical dose. We hypothesized that the clinical dose has supramaximal lung maturational effects.

STUDY DESIGN

We evaluated the full, half, and quarter clinical betamethasone dose (12 mg/70 kg or 170 microg/kg intramuscularly twice 24 hours apart) on fetal sheep lung pressure volume curves (PVC) after 48 hours' exposure at 0.75 gestation. We measured key messenger RNAs and protein products that affect lung function and total lung dipalmitoyl phosphatidyl choline.

RESULTS

Full and half doses had similar PVC and total lung dipalmitoyl phosphatidyl choline effects. Messenger RNA for surfactant proteins A, B, and D and elastin increased in a dose-dependent fashion.

CONCLUSION

Half the clinical betamethasone dose produces maximal PVC improvement in fetal sheep at 0.75 gestation.

The relationship between cortisol concentrations in pregnancy and systemic vascular resistance in childhood

OBJECTIVE

To assess the relationship between cortisol concentrations in the last trimester of pregnancy and systemic vascular resistance - SVR in childhood.

MATERIALS AND METHODS

This study is part of a cohort involving 130 Brazilian pregnant women and their children, ages 5 to 7years. Maternal cortisol was determined in saliva by an enzyme immunoassay utilizing the mean concentration of 9 samples of saliva (3 in each different day), collected at the same time, early in the morning. SVR was assessed by the HDI/PulseWave CR-2000 Cardiovascular Profiling System(R). Socioeconomic and demographic characteristics and life style factors were determined by a questionnaire. The nutritional status of the women and children was assessed by the body mass index - BMI. The association between maternal cortisol and SVR in childhood was calculated by multivariate linear regression analysis.

RESULTS

There were statistically significant associations between maternal cortisol and SVR (p=0.043) and BMI-z score of the children (p=0.027), controlling for maternal BMI, birth weight, age, and gender of the children.

CONCLUSION

As far as we know this is the first study in the literature assessing the association between cortisol concentrations in pregnancy and SVR in childhood. Overall, the data suggest that exposure to excess glucocorticoid in the prenatal period is associated to vascular complications in childhood, predisposing to cardiovascular diseases in later life.

Antenatal glucocorticoid therapy accelerates ATP production with creatine kinase increase in the growth-enhanced fetal rat heart

BACKGROUND

Previous study has demonstrated the increase of several cardiac function-related proteins, including creatine kinase (CK) as an important enzyme in the process of ATP synthesis in the fetal heart of rats administered glucocorticoid (GC) antenatally. In the present study the effect of antenatal GC administration on the CK expression in fetal and neonatal hearts was demonstrated.

METHODS AND RESULTS

Dexamethasone was administered to pregnant rats on days 19 and 20 of gestation. The mRNA levels of the CK isoforms, CK-M and Mi-CK, in 21-day-old fetal and 1-day-old neonatal hearts were significantly increased after antenatal GC administration. CK protein levels were also increased in both cultured cardiomyocytes and the mitochondria of the hearts. Uptake of 5, 5', 6, 6'-tetrachloro-1, 1', 3, 3'-tetraethyl-benzimidazolocarbocyanine iodide by mitochondria was significantly increased. An increased ATP level accompanied the CK increase in the neonatal hearts. Furthermore, in vitro these effects were mediated though the GC receptor of cardiomyocytes. Peroxisome proliferator-activated receptor gamma as the upstream transcription factor of CK was significantly increased in fetal hearts.

CONCLUSIONS

These results suggest that antenatal GC administration accelerates ATP synthesis through increased CK and may contribute to maturation of the premature heart so that it is ready for preterm delivery. (Circ J 2010; 74: 171 - 180).

Cardiovascular responses to maternal betamethasone administration in the intrauterine growth-restricted ovine fetus

OBJECTIVE

The objective was to characterize the effect of glucocorticoid treatment on fetal organ blood flow and regional cerebral blood flow in normally grown fetuses and fetuses with intrauterine fetal growth restriction (IUGR).

STUDY DESIGN

Studies were undertaken in both control and IUGR fetal sheep; growth restriction was induced by ligation of 1 umbilical artery. Fetuses received colored microspheres for organ blood flow calculations before and after 2 maternal betamethasone injections (BM1 and BM2).

RESULTS

Following BM1, cardiac output was significantly decreased in the control fetuses and blood flow to the heart and placenta was unchanged, whereas total cerebral blood flow was significantly decreased (P<.001), consistent with cerebral vasoconstriction. In the fetuses with IUGR, the cardiac output was significantly increased at +33 hours relative to BM1, and blood flow was increased in all organs; notably, there was a 2-fold increase in cerebral blood flow (P=.03).

CONCLUSION

The cardiovascular response of the fetus with IUGR to glucocorticoids is profoundly different from the control fetuses, which may induce both short- and long-term injury.

Early postnatal blood pressure in preterm infants: effects of chorioamnionitis and timing of antenatal steroids

Previous studies suggest postnatal blood pressure in preterm infants to be decreased by chorioamnionitis and increased by antenatal steroids (AS). We examined the adjusted effects of both antenatal modulators on postnatal blood pressure (BP), with separate effects reported for histologic chorioamnionitis with or without fetal involvement and timing of AS. General characteristics, BP, and heart rate values during the first 72 h after birth were obtained from 271 infants with gestational age <or=32.0 wk. In unadjusted analyses, chorioamnionitis was associated with lower BP, most prominently so in infants with fetal involvement, without an effect on hypotension incidence. AS increased BP and decreased the incidence of hypotension when administered within 7 d before birth. In a multivariable mixed model analysis, the AS effect remained significant, whereas chorioamnionitis was not independently predictive of postnatal BP. Other variables associated with increased postnatal BP were gestational age and umbilical artery pH, whereas hemolysis, elevated liver enzymes, low platelets syndrome was associated with decreased BP. In conclusion, AS seem to increase postnatal BP and decrease hypotension in preterm infants when given within 7 d before birth. Conversely, chorioamnionitis did not significantly affect postnatal BP after multivariable adjustment.

Effects of maternal global nutrient restriction on fetal baboon hepatic insulin-like growth factor system genes and gene products

Knowledge of altered maternal nutrition effects on growth-regulating systems is critical to understanding normal and abnormal fetal development. There are many reports of hepatic fetal IGF system responses to maternal nutrient restriction (MNR) during pregnancy in rodents and sheep but none in nonhuman primates. We determined effects of MNR on the fetal baboon hepatic IGF system. Social groups of female baboons were fed ad libitum, controls, or 70% controls (MNR) from 0.16 to 0.5 gestation and fetuses delivered by cesarean section. Fetal liver tissue was analyzed for IGF-I, IGF-II, and IGF binding protein (IGFBP)-3 mRNA by in situ hybridization and quantitative RT-PCR and protein by immunohistochemistry (IHC); IGF-I receptor, IGF-II receptor by quantitative RT-PCR and IHC and IGFBP-1 by in situ hybridization and IHC. MNR did not alter fetal body or liver weight. Fetal hepatic glycogen staining increased with MNR. MNR reduced fetal hepatic IGF-I and IGF-II and increased IGFBP-1 mRNA and decreased IGF-I, IGF-II, IGF-I receptor, and IGF-II receptor protein and increased protein for IGFBP-1 and IGFBP-3. MNR increased caspase-3, indicating apoptosis and decreased Akt staining, indicating decreased nutrient sensing. In conclusion, whereas fetal body and liver weights did not change in response to moderate MNR during the first half of baboon pregnancy, the major indices of function of the hepatic IGF system measured were all reduced.

Is nephrogenesis affected by preterm birth? Studies in a non-human primate model

Nephrogenesis occurs predominantly in late gestation at a time when preterm infants are already delivered. The aims of this study were to assess the effect of preterm birth and the effect of antenatal glucocorticoid treatment on nephrogenesis. Preterm baboons, which were delivered at 125 days gestation and ventilated for up to 21 days postnatally, were compared with gestational controls. A cohort of preterm baboons that had been exposed to antenatal glucocorticoids were compared with unexposed preterm baboons. The number of glomerular generations was estimated using a medullary ray glomerular-counting method, and glomerular number was estimated using unbiased stereology. CD31 and WT-1 localization was examined using immunohistochemistry and VEGF was localized using in situ hybridization. The number of glomerular generations was not affected by preterm birth, and total glomerular numbers were within the normal range. Kidneys were significantly enlarged in preterm baboons with a significant decrease in glomerular density (number of glomeruli per gram of kidney) in the preterm kidney compared with gestational controls. Neonates exposed to antenatal steroids had an increased kidney-to-body weight ratio and also more developed glomeruli compared with unexposed controls. Abnormal glomeruli, with a cystic Bowman's space and shrunken glomerular tuft, were often present in the superficial renal cortex of both the steroid-exposed and unexposed preterm kidneys; steroid exposure had no significant effect on the proportion of abnormal glomeruli. The proportion of abnormal glomeruli in the preterm kidneys ranged from 0.2 to 18%. In conclusion, although nephrogenesis is ongoing in the extrauterine environment, our findings demonstrate that preterm birth, independent of steroid exposure, is associated with a high proportion of abnormal glomeruli in some, but not all neonatal kidneys. Whether final nephron endowment is affected in those kidneys exhibiting a high proportion of abnormal glomeruli is yet to be confirmed.

The effects of the tocolytics atosiban and nifedipine on fetal movements, heart rate and blood flow

BACKGROUND

The choice of first-line tocolytic agent is a topic of worldwide debate. The oxytocin receptor antagonist atosiban and the calcium antagonist nifedipine appear to be effective in postponing delivery. However, information is lacking on their possible effects on the fetal biophysical profile.

OBJECTIVE

To study the direct fetal effects of tocolysis with atosiban or nifedipine combined with a course of betamethasone.

METHOD

We performed a randomised controlled study including women with preterm labour requiring tocolytic treatment. Primary outcome measures were the effects on fetal heart rate (FHR) and its variation. Secondary endpoints were the effects on fetal movement and blood flow (pulsatility index - PI) of the umbilical (UA) and medial cerebral arteries (MCA).

RESULTS

One-hour recordings of FHR and fetal movements were made on each of five successive days (days 0-4). Fetal blood flow velocity patterns were studied daily by Doppler ultrasound. Baseline characteristics of 31 women who had not delivered at day 0 and needed no escape tocolysis did not differ between the study groups. Multilevel analysis showed no significant effect of either tocolytic on FHR and movement parameters over the 5-day study period. The use of tocolytics also did not significantly alter the time courses of PI-values for UA (p = 0.37) and MCA (p = 0.62).

CONCLUSION

This study demonstrates for the first time the direct effects of atosiban on fetal movement, heart rate and blood flow. Tocolysis with either atosiban or nifedipine combined with betamethasone administration appears to have no direct fetal adverse effects.

Antenatal corticosteroid therapy: short-term effects on fetal behaviour and haemodynamics

Antenatal corticosteroid therapy to enhance fetal lung maturity in threatened preterm delivery has a number of non-pulmonary side-effects, both beneficial and undesirable. This review focuses on the short-term (transient) effects of betamethasone and dexamethasone on aspects of fetal circulation and behaviour which are used clinically as markers of fetal well-being. We summarise the effects observed, discuss the proposed underlying mechanisms, and emphasise the consequences for clinical decision-making. Recommendations are given to optimise medical care and to minimise the risk of unwarranted iatrogenic preterm delivery.

Predicting perinatal outcome through changes in umbilical artery Doppler studies after antenatal corticosteroids in the growth-restricted fetus

OBJECTIVE

To investigate whether persistently absent umbilical artery end-diastolic flow in the intrauterine growth-restricted fetus after betamethasone administration is associated with altered perinatal outcomes.

METHODS

This is a retrospective cohort study of 92 pregnancies complicated by intrauterine growth restriction (IUGR) and absent end-diastolic flow in which antenatal betamethasone was given. Predefined maternal outcomes (maternal age, gestational age at diagnosis of absent end-diastolic flow, gestational age at delivery, preexisting medical conditions) and neonatal outcomes (including birth weight; perinatal mortality; duration of neonatal intensive care unit admission; requirement for intubation, assisted ventilation, inotropic support; duration of supplemental oxygen, assisted ventilation; respiratory distress syndrome, necrotizing enterocolitis, intraventricular hemorrhage) were analyzed.

RESULTS

Betamethasone administration was associated with a transient return of end-diastolic umbilical artery flow in 58 pregnancies (63%) and persistent absent end-diastolic flow in 34 (37%). Persistent absent end-diastolic flow was seen more frequently in women with prepregnancy medical disorders (59% compared with 24%, P<.001). Neonates from the persistent absent end-diastolic flow subgroup were more likely to require assisted ventilation (93.1% compared with 73.5%, P=.03) and to have longer durations of assisted ventilation (median time 30 days compared with 4 days, P=.03) and supplemental oxygen (median time 45 days compared with 4 days, P=.04).

CONCLUSION

Betamethasone administration is associated with a transient return of end-diastolic flow in two thirds of pregnancies complicated by IUGR and umbilical artery absent end-diastolic flow. Persistent absent end-diastolic flow in the umbilical artery after betamethasone administration may identify a subgroup of fetuses with IUGR at further heightened perinatal risk that, as neonates, are more likely to require assisted ventilation and a longer duration of ventilation and supplemental oxygen.

Antenatal and postnatal risk factors for neonatal hypertension and infant follow-up

Neonatal hypertension is an uncommon but important complication of intensive care management. The aims of this study were to identify in neonates with hypertension: antenatal and postnatal risk factors; aldosterone and renin levels; and report on outcome in early infancy. The study involved a retrospective review of neonates diagnosed with systemic hypertension from January 2001 to December 2005. Demographic data, risk factors, laboratory investigation, and follow-up data at 3-6 months of age were collected. Of the 2,572 newborn infants included, 34 (1.3%) had neonatal hypertension. Gestational age and birth weight and length were significantly lower in infants with hypertension. The median postnatal age at diagnosis of systemic hypertension was 5.0 days. Antenatal steroid administration, maternal hypertension, umbilical arterial catheter, postnatal acute renal failure, patent ductus arteriosus, indomethacin treatment and chronic lung disease were associated with the development of neonatal hypertension [odds ratios (OR) 8.7, 3.8, 10.0, 51.8, 5.9, 5.7 and 7.7, respectively]. Elevated aldosterone and renin levels occurred in 60% and 33% but had normalised in the majority by 6 months of age. The majority of infants do not require treatment for hypertension by 6 months of age.

Mechanisms underlying the role of glucocorticoids in the early life programming of adult disease

Compelling epidemiological evidence suggests that exposure to an adverse intrauterine environment, manifested by low-birth weight, is associated with cardiometabolic and behavioural disorders in adulthood. These observations have led to the concept of ‘fetal programming’. The molecular mechanisms that underlie this relationship remain unclear, but are being extensively investigated using a number of experimental models. One major hypothesis for early life physiological programming implicates fetal overexposure to stress (glucocorticoid) hormones. Several animal studies have shown that prenatal glucocorticoid excess, either from endogenous overproduction with maternal stress or through exogenous administration to the mother or fetus, reduces birth weight and causes lifelong hypertension, hyperglycaemia and behavioural abnormality in the offspring. Intriguingly, these effects are transmitted across generations without further exposure to glucocorticoids, which suggests an epigenetic mechanism. These animal observations could have huge implications if extrapolated to humans, where glucocorticoids have extensive therapeutic use in obstetric and neonatal practice.

Prenatal dexamethasone exposure induces changes in nonhuman primate offspring cardiometabolic and hypothalamic-pituitary-adrenal axis function

Prenatal stress or glucocorticoid administration has persisting "programming" effects on offspring in rodents and other model species. Multiple doses of glucocorticoids are in widespread use in obstetric practice. To examine the clinical relevance of glucocorticoid programming, we gave 50, 120, or 200 microg/kg/d of dexamethasone (dex50, dex120, or dex200) orally from mid-term to a singleton-bearing nonhuman primate, Chlorocebus aethiops (African vervet). Dexamethasone dose-dependently reduced maternal cortisol levels without effecting maternal blood pressure, glucose, electrolytes, or weight gain. Birth weight was unaffected by any dexamethasone dose, although postnatal growth was attenuated after dex120 and dex200. At 8 months of age, dex120 and dex200 offspring showed impaired glucose tolerance and hyperinsulinemia, with reduced (approximately 25%) pancreatic beta cell number at 12 months. Dex120 and dex200 offspring had increased systolic and diastolic blood pressures at 12 months. Mild stress produced an exaggerated cortisol response in dex200 offspring, implying hypothalamic-pituitary-adrenal axis programming. The data are compatible with the extrapolation of the glucocorticoid programming hypothesis to primates and indicate that repeated glucocorticoid therapy and perhaps chronic stress in humans may have long-term effects.