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

Sex differences in modulation of fetoplacental vascular resistance in growth-restricted mouse fetuses following betamethasone administration: comparisons with human fetuses

BACKGROUND

Maternally administered corticosteroids are routinely used to accelerate fetal lung maturation in pregnancies at risk of early preterm delivery. Although, among the subgroup with growth restriction, a majority show a temporary improvement in umbilical artery Doppler waveforms that may be sustained up to 7 days, a minority will acutely decompensate in response to corticosteroids in association with deteriorating umbilical and fetal Doppler waveforms. The basis for such acute Doppler changes is presently unknown. Our group has developed a noninvasive ultrasound methodology to measure wave reflections in the umbilical artery and have established that wave reflection metrics are sensitive to structural changes in the placental vasculature and to acute changes in vascular tone. Using this approach, we demonstrated in healthy pregnant mice that fetoplacental vascular resistance decreased in betamethasone-treated mice compared with saline-treated controls.

OBJECTIVE

This study aimed to investigate the effects of betamethasone administration on the wave reflection metrics in a mouse model of fetal growth restriction and to compare these findings with equivalent measurements in human fetuses.

STUDY DESIGN

Pregnant CD-1 mice were housed from embryonic day 14.5 to embryonic day 17.5 in either a normoxic (21% O₂, n=24) or hypoxic environment (11% O₂, n=22), the latter being an established mouse model of fetal growth restriction. To investigate the effect of maternally administered betamethasone on the fetoplacental vasculature, ultrasound imaging was performed at baseline and 4 hours after treatment (either betamethasone or sterile saline). Umbilical artery wave reflection metrics were compared between the groups and for the effect of fetal sex. In addition, a cohort of 10 pregnant women with elevated umbilical artery pulsatility index and evidence of fetal growth restriction and 6 controls were imaged before and after corticosteroid administration.

RESULTS

In the mouse model, after betamethasone administration, the female fetuses from the hypoxia group showed a 15% increase in umbilical artery diameter, a 98% increase in umbilical artery blood flow, and a 27% decrease in umbilical artery reflection coefficient, whereas the males from the hypoxia group showed no substantial changes. In agreement with our mouse findings, umbilical artery reflections were found to be larger in human growth-restricted fetuses than controls in women at risk of preterm birth.

CONCLUSION

Our studies provide insight into the mechanism whereby the human growth-restricted fetus may exhibit a temporary favorable fetoplacental vascular response to maternally administered corticosteroids. Further investigations are needed to understand why the male growth-restricted fetus seems unable to mount this favorable vascular response.

Antenatal glucocorticoids, magnesium sulfate, and mode of birth in preterm fetal small for gestational age

A diagnosis of fetal growth restriction and subsequent preterm birth is associated with increased risks of adverse perinatal and neurodevelopmental outcomes and potentially long-lasting effects to adulthood. Most such cases are associated with placental insufficiency and the fetal response to chronic intrauterine hypoxemia and nutrient deprivation leads to substantial physiological and metabolic adaptations. The management of such pregnancies, especially with respect to perinatal interventions and birth mode, remains an unresolved dilemma. The benefits from standard interventions for threatened preterm birth may not be necessarily translated to pregnancies with small-for-gestational-age fetuses. Clinical trials or retrospective studies on outcomes following administration of antenatal glucocorticoids and magnesium sulfate for neuroprotection when preterm birth is imminent either have yielded conflicting results for small-for-gestational-age fetuses, or did not include this subgroup of patients. Experimental models highlight potential harmful effects of administration of antenatal glucocorticoids and magnesium sulfate in the pregnancies with fetal small for gestational age although clinical data do not substantiate these concerns. In addition, heterogeneity in definitions of fetal small for gestational age, variations in the inclusion criteria, and the glucocorticoid regime contribute to inconsistent results. In this review, we discuss the physiologic adaptions of the small-for-gestational-age fetus to its abnormal in utero environment in relation to antenatal glucocorticoids; the impact of antenatal glucocorticoids and intrapartum magnesium sulfate in pregnancies with fetal small for gestational age; the current literature on birth mode for pregnancies with fetal small for gestational age; and the knowledge gaps in the existing literature.

Antenatal corticosteroids and outcomes of preterm small-for-gestational-age neonates in a single medical center

Objective

This study investigated the effect of an antenatal corticosteroid (ACS) in preterm small-for-gestational-age (SGA) neonate.

Methods

This study was a retrospective cohort study. We compared women who received ACS with unexposed controls and evaluated neonatal complications among those having a singleton SGA neonate born between 29 and 34 complete gestational weeks. The neonates born after 32 weeks of gestation were divided into subgroups. Multivariable logistic regression analysis was performed.

Results

A total 82 of the preterm infants met inclusion criteria; 57 (69.5%) were born after 32 weeks of gestation. There were no significant differences in terms of mechanical ventilation, seizure, intracranial hemorrhage, retinopathy of prematurity, necrotizing enterocolitis, feeding difficulty, and neonatal mortality between infants whose mothers received ACS ant those whose mothers did not (all P>0.05). However, newborns whose mothers received ACS exhibited a significantly increased risk of developing respiratory distress syndrome (RDS) (adjusted odds ratio [aOR], 3.271; 95% confidence interval [CI], 1.038–10.305; P=0.043). In case of neonates born beyond 32 weeks of gestation, the risk of neonatal hypoglycemia was significantly higher in women receiving ACS after controlling for confounding factors (aOR, 5.832; 95% CI, 1.096–31.031; P=0.039).

Conclusion

ACS did not improve neonatal morbidities, in SGA neonates delivered between 29 and 34 gestational weeks. Rather, ACS could increase the risk of RDS. In cases of SGA neonate delivered between 32 and 34 complete gestational weeks, the risk of hypoglycemia was significantly increased. The use of ACS in women with preterm SGA infants needs to be evaluated further, especially after 32 weeks' gestation.

Efficacy of Antenatal Corticosteroid Treatment on Neurodevelopmental Outcome according to Head Circumference at Birth

BACKGROUND

There are concerns about the efficacy of antenatal corticosteroid treatment (ACT) in the growth-restricted fetus.

OBJECTIVE

To evaluate the effect of ACT on neurodevelopmental outcome at 2 years of corrected age according to the z score of birth head circumference (ZS HC) in a large prospective cohort of preterm infants.

METHODS

This study was conducted as a population-based, prospective, multicenter study, including 4,965 infants born between 24 and 33 weeks' gestation and whose status regarding ACT and the measurement of head circumference at birth were available. They were evaluated at 2 years of corrected age to assess neurological outcome. Three approaches were considered to estimate the effect of ACT on neurodevelopment: (i) logistic regression with adjustment on propensity score, (ii) weighted logistic regression using the inverse probability of treatment weighting method, and (iii) 1:1 matching of gestational age, ZS HC, and propensity score between treated and nontreated infants.

RESULTS

ACT was documented in 60% of infants. Three groups of infants were considered according to their ZS HC: between -3 and -1 standard deviation (SD), -1 and +1 SD, and +1 and +3 SD, respectively. ACT was associated with a significant improvement of neurodevelopmental outcome only for infants with an ZS HC of between +1 and +3 SD (adjusted OR 1.72; 95% CI 1.06-2.79). Moreover, ORs estimated in the -3 to -1 and +1 to +3 categories were significantly different.

CONCLUSION

We found beneficial effects of ACT on neurodevelopmental outcomes at 2 years of corrected age only in preterm infants with a ZS HC >1 SD.

Effect of corticosteroids on cardiac function in growth-restricted fetuses

OBJECTIVE

To determine the acute effects of corticosteroids on the cardiovascular system in growth-restricted fetuses.

METHODS

This was a prospective cohort study conducted at a tertiary hospital between January 2011 and October 2013. Fetal cardiovascular function in fetuses with intrauterine growth restriction (IUGR) was assessed immediately before and 24 h after the first dose of betamethasone, administered in routine management of IUGR. Fetal arterial and venous Dopplers were assessed. Fetal cardiac function was evaluated by tissue Doppler echocardiography, with the assessment of both left and right ventricular function by calculating myocardial performance index (MPI') and E':A' ratios. Values were compared before and after exposure.

RESULTS

Seventeen patients were included at a mean gestational age of 34 + 1 (range, 29 + 1 to 37 + 4) weeks. Fifteen fetuses were below the 5(th) percentile and two were below the 10(th) percentile for estimated fetal weight and abdominal circumference and all had no interval growth during a 2-week period. There was a decrease in right MPI' (from 0.56 to 0.47; P = 0.007) after corticosteroid exposure but no change in left MPI' (from 0.49 to 0.48). Right MPI' was higher than left MPI' before exposure (0.56 vs 0.49, respectively; P = 0.001), but not after exposure (P = 0.55). There was no change in left or right ventricular E':A' ratios and no difference was detected in umbilical artery, middle cerebral artery or ductus venosus pulsatility index following administration of corticosteroids.

CONCLUSIONS

Corticosteroids altered right-sided, but not left-sided, tissue Doppler MPI' in IUGR fetuses, with no detectable change in arterial or venous Doppler pulsatility indices. Before exposure, the mean right MPI' was higher than the left. However, after exposure, there was no difference, suggesting that corticosteroids may reverse the negative effect of IUGR on fetal heart function. Large prospective studies with a larger sample size are needed to confirm this finding. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Controversial clinical practices for patients with preeclampsia or HELLP syndrome: a survey

BACKGROUND

Considerable controversy continues to surround the management of severe preeclampsia and HELLP syndrome. Experts, researchers, and those published in the field were surveyed about their specific practices.

MATERIALS AND METHODS

An extensive literature search was undertaken to identify the cohort of authors with recent publications on the subjects of preeclampsia (2009-2012) and HELLP syndrome (2005-2012). Online surveys were sent to all authors using the email addresses found in their publications.

RESULTS

Surveys were delivered by email to 363 authors of preeclampsia publications and 91 authors of HELLP syndrome publications. Completed surveys were received from 61 (13.4%) of the group. Except for consensus about the indication of corticosteroids for the enhancement of fetal lung maturation, there was considerable variation in corticosteroid practice and anesthesia techniques.

CONCLUSIONS

A marked diversity in practice characterized the clinical care rendered by experts in the field of preeclampsia and HELLP syndrome. Thus, there is an urgent need for well-designed and executed prospective clinical trials to improve the evidence for best consensus practice in this area of obstetrical medicine.

Prenatal corticosteroids modify glutamatergic and GABAergic synapse genomic fabric: insights from a novel animal model of infantile spasms

Prenatal exposure to corticosteroids has long-term postnatal somatic and neurodevelopmental consequences. Animal studies indicate that corticosteroid exposure-associated alterations in the nervous system include hypothalamic function. Infants with infantile spasms, a devastating epileptic syndrome of infancy with characteristic spastic seizures, chaotic irregular waves on interictal electroencephalogram (hypsarhythmia) and mental deterioration, have decreased concentrations of adrenocorticotrophic hormone (ACTH) and cortisol in cerebrospinal fluid, strongly suggesting hypothalamic dysfunction. We have exploited this feature to develop a model of human infantile spasms by using repeated prenatal exposure to betamethasone and a postnatal trigger of developmentally relevant spasms with NMDA. The spasms triggered in prenatally primed rats are more severe compared to prenatally saline-injected ones and respond to ACTH, a treatment of choice for infantile spasms in humans. Using autoradiography and immunohistochemistry, we have identified a link between the spasms in our model and the hypothalamus, especially the arcuate nucleus. Transcriptomic analysis of the arcuate nucleus after prenatal priming with betamethasone but before trigger of spasms indicates that prenatal betamethasone exposure down-regulates genes encoding several important proteins participating in glutamatergic and GABAergic transmission. Interestingly, there were significant sex-specific alterations after prenatal betamethasone in synapse-related gene expression but no such sex differences were found in prenatally saline-injected controls. A pairwise relevance analysis revealed that, although the synapse gene expression in controls was independent of sex, these genes form topologically distinct gene fabrics in males and females and these fabrics are altered by betamethasone in a sex-specific manner. These findings may explain the sex differences with respect to both normal behaviour and the occurrence and severity of infantile spasms. Changes in transcript expression and their coordination may contribute to a molecular substrate of permanent neurodevelopmental changes (including infantile spasms) found after prenatal exposure to corticosteroids.

Corticosteroids effect on caspase 3 expression in an in-vitro model of hypoxic brain cells

OBJECTIVE

Effects of corticosteroids (CS) in the brain of growth-restricted fetus remain largely unstudied. We investigated if dexamethasone (DXM) exposure contributes to neuronal injury in an in-vitro model of neuronal cells under hypoxic conditions (surrogate for fetal growth restriction).

STUDY DESIGN

U87 glioblastoma cells exposed to hypoxic or normoxic conditions for 10 h were incubated in the absence or presence of DXM for 48 h. Apoptosis as possible indicator of neurotoxicity was determined using a caspase-3-specific activity assay and western blotting. Caspase-3 was calculated as percentage of mean caspase-3 cleavage. Each experiment was performed in triplicate (n = 48). Caspase 3 activity in cell culture media was also measured by ELISA.

RESULTS

Pro-caspase-3 (32 kDa) was expressed in culture, but activated 17 Kd caspase 3 was not expressed in cell lysate. There was no difference in ratio of caspase 3 activation when U87 cells were exposed to 10 v of hypoxia as compared to normoxia (0.46 ± 0.44 versus 0.37 ± 0.37). The pro-apoptotic effects of DXM were not increased by pre-exposure to hypoxia: (0.37 ± 0.37 versus 0.47 ± 0.40).

CONCLUSION

The addition of DXM to hypoxic U87 cells had no additive or synergistic effects on the activation of caspase 3. Therefore, we speculate that the administration of CS in the setting of fetal growth restriction would not lead to increased apoptosis with potential neuronal injury.

Doppler assessment of the fetus with intrauterine growth restriction

OBJECTIVE

We sought to provide evidence-based guidelines for utilization of Doppler studies for fetuses with intrauterine growth restriction (IUGR).

METHODS

Relevant documents were identified using PubMed (US National Library of Medicine, 1983 through 2011) publications, written in English, which describe the peripartum outcomes of IUGR according to Doppler assessment of umbilical arterial, middle cerebral artery, and ductus venosus. Additionally, the Cochrane Library, organizational guidelines, and studies identified through review of the above were utilized to identify relevant articles. Consistent with US Preventive Task Force suggestions, references were evaluated for quality based on the highest level of evidence, and recommendations were graded.

RESULTS AND RECOMMENDATIONS

Summary of randomized and quasirandomized studies indicates that, among high-risk pregnancies with suspected IUGR, the use of umbilical arterial Doppler assessment significantly decreases the likelihood of labor induction, cesarean delivery, and perinatal deaths (1.2% vs 1.7%; relative risk, 0.71; 95% confidence interval, 0.52-0.98). Antepartum surveillance with Doppler of the umbilical artery should be started when the fetus is viable and IUGR is suspected. Although Doppler studies of the ductus venous, middle cerebral artery, and other vessels have some prognostic value for IUGR fetuses, currently there is a lack of randomized trials showing benefit. Thus, Doppler studies of vessels other than the umbilical artery, as part of assessment of fetal well-being in pregnancies complicated by IUGR, should be reserved for research protocols.

Antenatal corticosteroids in the management of preterm birth: are we back where we started?

Though the preterm birth rate in the United States has finally begun to decline, preterm birth remains a critical public health problem. The administration of antenatal corticosteroids to improve outcomes after preterm birth is one of the most important interventions in obstetrics. This article summarizes the evidence for antenatal corticosteroid efficacy and safety that has accumulated since Graham Liggins and Ross Howie first introduced this therapy. Although antenatal corticosteroids have proven effective for singleton pregnancies at risk for preterm birth between 26 and 34 weeks’ gestation, questions remain about the utility in specific patient populations such as multiple gestations, very early preterm gestations, and pregnancies complicated by IUGR. In addition, there is still uncertainty about the length of corticosteroid effectiveness and the need for repeat or rescue courses. Though a significant amount of data has accumulated on antenatal corticosteroids over the past 40 years, more information is still needed to refine the use of this therapy and improve outcomes for these at-risk patients.