Antenatal corticosteroids and perinatal outcome in late fetal growth restriction: analysis of prospective cohort

Understanding a Potential Role for the NLRP3 Inflammasome in Placenta-Mediated Pregnancy Complications

Stillbirth affects approximately 2 million pregnancies annually and is closely linked to placental dysfunction, which may also present clinically as foetal growth restriction (FGR) or pre-eclampsia (PE). Placental dysfunction can arise from a range of insults, including the inflammatory conditions villitis of unknown aetiology (VUE) and chronic histiocytic intervillositis (CHI). Despite ample research regarding the pathophysiology of placental dysfunction, the literature surrounding placental inflammation is more limited, with no currently established treatments. In the absence of infection, placental inflammation is hypothesised to be stimulated by damage-associated molecular patterns (DAMPs), known as sterile inflammation. The NLRP3 inflammasome, a protein scaffold that unites within the cytosol of cells, is a proposed contributor. The NLRP3 inflammasome is dysregulated in numerous diseases and has shown evidence of activation through the sterile inflammatory pathway via DAMPs. Studies have demonstrated the upregulation of the NLRP3 inflammasome and its components in placentally-mediated pregnancy pathologies. However, the link between placental dysfunction seen in these disorders and the NLRP3 inflammasome is not yet firmly established. This manuscript aims to review the evidence regarding placental inflammation seen with placental dysfunction, discuss its association with the NLRP3 inflammasome, and identify potential therapeutic interventions for this pathological inflammatory response.

Maternal MitoQ Treatment Is Protective Against Programmed Alterations in CYP Activity Due to Antenatal Dexamethasone

Background/Objectives: In pregnancy threatened by preterm birth, antenatal corticosteroids (ACS) are administered to accelerate fetal lung maturation. However, they have side effects, including the production of reactive oxygen species that can impact cytochrome P450 (CYP) activity. We hypothesised that antioxidants could protect a fetus treated with ACS during gestation and prevent the programming of altered hepatic CYP activity in the offspring. The primary outcome of our study was the impact of different maternal treatments on the activity of hepatic drug-metabolising enzymes in offspring. Methods: At 100 ± 1 days gestational age (dGA, term = 147 dGA), 73 ewes were randomly allocated to the following: saline (5 mL IV daily 105-137 ± 2 dGA, n = 17), ACS (Dexamethasone (Dex); 12 mg IM at 115 and 116 dGA; n = 25), MitoQ (6 mg/kg MS010 IV, daily bolus 105-137 ± 2 dGA; n = 17) or Dex and MitoQ (Dex+MitoQ; n = 14). CYP activity and protein abundance were assessed using functional assays and Western blot. Results: Dex decreased the hepatic activity of fetal CYP3A (-56%, PDex = 0.0322), and 9 mo lamb CYP1A2 (-22%, PDex = 0.0003), CYP2B6 (-36%, PDex = 0.0234), CYP2C8 (-34%, PDex = 0.0493) and CYP2E1 (-57%, PDex = 0.0009). For all, except CYP1A2, activity returned to control levels with Dex+MitoQ in 9 mo lambs. In 9 mo lambs, MitoQ alone increased activity of CYP2B6 (+16%, PMitoQ = 0.0011) and CYP3A (midazolam, +25%, PMitoQ = 0.0162) and increased CAT expression (PMitoQ = 0.0171). Dex+MitoQ increased CYP3A4/5 activity (testosterone, +65%, PIntx < 0.0003), decreased CYP1A2 activity (-14%, PIntx = 0.0036) and decreased mitochondrial abundance (PIntx = 0.0051). All treatments decreased fetal hepatic DRP1, a regulator of mitochondrial fission (PDex = 0.0055, PMitoQ = 0.0006 and PIntx = 0.0034). Conclusions: Antenatal Dex reduced activity of only one CYP in the fetus but programmed the reduced activity of several hepatic CYPs in young adult offspring, and this effect was ameliorated by combination with MitoQ.

Outcomes in Pregnancies Complicated with Preterm Hypertensive Disorders with and without Late Antenatal Corticosteroids

OBJECTIVE

 This study aimed to determine whether administration of a late preterm (34-36 weeks) course of antenatal corticosteroids (ACS) is associated with improved short-term neonatal outcomes among pregnancies complicated with hypertensive disorders of pregnancy (HDP) who delivered in the late preterm period.

STUDY DESIGN

 A single tertiary center retrospective cohort study, including pregnant individuals with singleton fetuses who delivered between 34.0 and 36.6 weeks following an HDP diagnosis. Exclusion criteria were major fetal anomalies and treatment with ACS before 34 weeks. Cases were divided into two groups: exposed group, consisting of individuals treated with a late ACS course, and nonexposed group, receiving no ACS. The primary outcome was a composite adverse neonatal outcome, including intensive care unit admission, oxygen treatment, noninvasive positive pressure ventilation, mechanical ventilation, respiratory distress syndrome, transient tachypnea, or apnea of prematurity. Secondary neonatal outcomes included birth weight, Apgar score, intraventricular hemorrhage, necrotizing enterocolitis, bronchopulmonary dysplasia, surfactant use, hypoglycemia, hyperbilirubinemia, sepsis, and neonatal death. Multivariable regression models were used to determine adjusted odds ratio (aOR)and 95% confidence intervals (CIs).

RESULTS

Of 7,624 preterm singleton deliveries during the study period, 438 (5.7%) were diagnosed with HDP and delivered between 34.0 and 36.6 weeks. Infants who received ACS were diagnosed more commonly with fetal growth restriction (16.0 vs. 5.6%, p < 0.01) and were delivered at an earlier gestational age (GA) (mean GA: 35.6 vs. 36.3 weeks, p < 0.01). The composite neonatal morbidity did not differ between the groups after adjustments (aOR: 0.97, 95% CI: 0.47, 1.98). Neonatal hypoglycemia and hyperbilirubinemia were more common in the exposed group than in the nonexposed group (46.9 vs. 27.4%; aOR: 2.27; 95% CI: 1.26, 4.08 and 64.2 vs. 46.5%; aOR: 2.08; 95% CI: 1.16, 3.72 respectively).

CONCLUSION

 In people with HDP, a course of ACS given in the late preterm period did not improve neonatal morbidity.

KEY POINTS

· In people with HDP, a late preterm ACS course did not improve neonatal morbidity.. · Respiratory morbidity rate was similar between infants who received late ACS and those who did not.. · Neonatal hypoglycemia and hyperbilirubinemia were more common in infants who received late ACS..

Antenatal corticosteroids for late small-for-gestational-age fetuses

OBJECTIVES

To compare neonatal morbidity in late preterm pregnancies with small-for-gestational-age fetuses, between those exposed and not exposed to antenatal corticosteroids (ACS).

METHODS

A retrospective study which included growth-restricted fetuses delivered at gestational week 34+0 to 36+6 weeks at a tertiary university-affiliated hospital, from March 2016 to March 2022. The primary composite outcome included the need for oxygen therapy or ventilation, respiratory distress syndrome, transient tachypnea of the newborn, bronchopulmonary dysplasia, necrotizing enterocolitis, intraventricular hemorrhage grade III/IV and neonatal mortality.

RESULTS

The primary composite outcome was comparable between those who did and did not receive ACS (26.1 vs. 20.8 %, p=0.512). Neonatal morbidity rates did not differ significantly between the groups, except for hypoglycemia, which was more common among neonates from ACS-exposed mothers (37.0 vs. 19.5 %, p=0.037). Multivariate analysis, adjusted for gestational diabetes and the mode of delivery showed no significant difference in the composite outcome between the groups (OR=2.03, 95 % CI 0.79-5.20, p=0.142). Cesarean delivery was associated with a higher risk of the primary outcome (OR=2.13, 95 % CI 1.17-3.85, p=0.013). After excluding those who did not receive the initial betamethasone dose within 2-7 days before delivery, the primary composite outcome remained similar between the groups. The primary composite outcome was similar among severely growth-restricted fetuses (<5th percentile) exposed and not exposed to ACS (29.2 vs. 22.0 %, p=0.560).

CONCLUSIONS

Among preterm pregnancies complicated by small-for-gestational-age fetuses, ACS did not lower the rate of neonatal morbidity.

Causal Relationships Between Leukocyte Subsets and Adverse Fetal Outcomes: A Mendelian Randomization Study

Background: The tolerance and dynamic regulation of the maternal immune system during pregnancy are pivotal for ensuring fetal health. Immune cell subsets play a complex and crucial role in this process, closely linked to the neonatal health status. Despite recognizing the significance of dysregulation in the quantity and activity of immune cells in neonatal disease occurrence, their specific roles remain elusive, resulting in a dearth of clinically viable interventions for immune-mediated neonatal diseases. Materials and Methods: Employing two-sample Mendelian randomization (MR) methodology, this study systematically investigated 446 leukocyte features (N = 500,675), including leukocyte subsets, absolute cell (AC) counts, and morphological parameters (MP) and their correlation with seven adverse fetal outcomes (N = 1,100,458), encompassing fetal growth restriction (FGR), preterm birth (PTB), neonatal jaundice (NNJ), digestive system disorders of fetus and newborn (DSDFN), hemorrhagic and hematological disorders of fetus and newborn (HDFN), respiratory distress of newborn (RDN), and transitory disorders of metabolism specific to fetus and newborn (TDMSFN). Results: The results unveiled significant causal relationships between 301 leukocyte subsets and these seven adverse fetal outcomes, with 259, 245, 15, 44, 11, 32, and 68 pairs of notable associations for each adverse outcome, respectively. Furthermore, the study highlighted potential pathogenic mechanisms underlying the mutual influence among neonatal diseases. MR results indicated FGR as a robustly correlated risk factor for PTB and NNJ and showed a reciprocal causal relationship between NNJ and FGR. PTB exhibited a positive correlation with HDFN. Conclusions: This study provided profound insights into the intricate regulatory mechanisms of leukocyte subsets in neonatal diseases, paving the way for new avenues in the diagnosis and treatment of associated disorders.

Respiratory morbidity among offspring misclassified as growth restricted

OBJECTIVE

An ultrasound-based diagnosis implies that some fetuses suspected to be growth-restricted (FGR) are discovered at birth to be appropriately grown (appropriate for gestational age [AGA] birth weight, between the 10th and 90th percentile). These fetuses may thus be exposed to unnecessary medical interventions, including early labor induction. In this study, we have evaluated the long-term respiratory health of offspring misclassified as FGR.

STUDY DESIGN

A population-based cohort analysis was conducted, including deliveries of AGA singletons between 1991 and 2021 at a tertiary referral hospital. Incidence of morbidity due to various respiratory conditions was compared between AGA offspring with prenatal diagnosis of FGR, and those without a false diagnosis of FGR. The Kaplan-Meier approach was used to estimate cumulative morbidity incidence. The stratified Cox proportional-hazards model was used to control for confounders.

RESULTS

A total of 324,620 deliveries of AGA newborns were included in the analyses; 3249 of them (1.0%) were misclassified prenatally as FGR. The FGR subgroup delivered at an earlier gestational age (36.7 vs. 39.1 weeks, p < .001) and had more than 25% higher incidence of respiratory-related morbidity during childhood (33.2% vs. 26.5%), specifically related to asthma and obstructive sleep apnea (p < .001 for all). A higher cumulative morbidity rate due to respiratory conditions was observed in the Kaplan-Meier survival curve (log-rank p value < .001). This association between FGR and respiratory morbidity was independent of preterm delivery, maternal age, cesarean delivery, and child's birth year (adjusted hazard ratio = 1.14, 95% confidence interval: 1.07-1.21, p < .001), using a Cox proportional hazards model.

CONCLUSION

AGA newborns misclassified as FGR, are at an increased risk for long-term respiratory morbidity during childhood and adolescence.

Administration of Antenatal Corticosteroids: Optimal Timing

The effectiveness of antenatal corticosteroids (ACS) in significantly reducing respiratory distress syndrome (RDS) depends crucially on the timing. It is successful if delivery takes place between 24 hours and seven days following administration; after this period, the side effects seem to predominate. In addition, an increased rate of mental impairment and behavioral disorders are observed in children born full-term after ACS administration. The optimal timing of ACS administration depends crucially on the given indication; to date, it has been achieved in only 25-40% of cases. ACS administration is always indicated in PPROM, in severe early pre-eclampsia, in fetal IUGR with zero or reverse flow in the umbilical artery, in placenta previa with bleeding, and in patients experiencing premature labor with a cervical length < 15 mm. The risk of women with asymptomatic cervical insufficiency giving birth within seven days is very low. In this case, ACS should not be administered even if the patient's cervical length is less than 15 mm, provided that the cervix is closed and there are no other risk factors for a premature birth. The development of further diagnostic methods with improved power to predict premature birth is urgently needed in order to optimize the timing of ACS administration in this patient population. Caution when administering ACS is also indicated in women experiencing premature labor who have a cervical length ≥ 15 mm. Further studies using amniocentesis are needed in order to identify the patient population with microbial invasion of the amniotic cavity/intra-amniotic infection (MIAC/IAI), and to define threshold values at which delivery is indicated. ACS administration is not performed as an emergency measure, usually not even before transfer to a perinatal center. Therefore, whenever possible, the indication for ACS administration should be determined by a clinician who is highly experienced in perinatology.