Timing of antenatal steroid administration for imminent preterm birth: results of a prospective observational study in Germany

The Interaction of Antenatal Steroid Timing and Pre-Eclampsia on Respiratory Outcomes Among Infants Born Preterm

OBJECTIVE

To evaluate the effect of timing of antenatal steroid (ANS) administration and its interaction with pre-eclampsia on respiratory outcome among infants born preterm.

STUDY DESIGN

This was an analysis of a prospective, single-center cohort of infants born between 23 and 30 weeks of gestation between 2012 through 2021. End points were severe respiratory distress syndrome (sRDS) and moderate-to-severe bronchopulmonary dysplasia (msBPD). ANS administration was classified as within 7 days of birth or earlier than 7 days before birth. Multivariable generalized estimating equations were used to model the association between ANS timing and pre-eclampsia with the end points.

RESULTS

The cohort included 1172 infants, of whom 30% were born to mothers with pre-eclampsia and 83% to mothers who received ANS within 7 days of birth. Compared with non-pre-eclampsia with ANS within 7 days of birth, pre-eclampsia with ANS earlier than 7 days before birth was associated with an increased risk for sRDS. Pre-eclampsia with ANS within 7 days of birth was not associated with an increased risk for sRDS. Compared with non-pre-eclampsia with ANS within 7 days of birth, non-pre-eclampsia with ANS earlier than 7 days of birth, and pre-eclampsia with ANS earlier than 7 days before birth were associated with an increased risk for msBPD. Pre-eclampsia with ANS within 7 days of birth was not associated with increased risk of msBPD.

CONCLUSIONS

In this cohort, properly timed maternal ANS administration within 7 days of birth was associated with a reduced risk of sRDS and msBPD among infants born preterm to mothers with pre-eclampsia. These findings underscore the need to optimize the timing of ANS administration.

The association of placental to fetal ratio with pregnancy duration

INTRODUCTION

Our objective was to study the association of placental size, fetal size, and placental size relative to fetal size (placental to fetal ratio) at gestational week 27 with time to spontaneous delivery.

MATERIAL AND METHODS

We included 100 pregnancies in a follow-up study from gestational week 27 until spontaneous delivery. Placental and fetal volume (in cm3) were measured at gestational week 27 by magnetic resonance imaging (MRI), and the association of placental to fetal ratio (placental volume/fetal volume) with delivery after spontaneous onset of labor was estimated as hazard ratios (HR) by applying Cox regression models. Pregnancies with deliveries after planned cesarean section or induction of labor provided follow-up time until these events. An HR lower than 1.0 indicates decreased risk of spontaneous delivery.

RESULTS

Mean placental volume was 532 cm3 (SD 136 cm3) at gestational week 27, and fetal volume was 961 cm3 (SD 112 cm3). This yielded a mean placental to fetal ratio of 0.55 (SD 0.12). The HR of spontaneous delivery decreased with increasing placental to fetal ratio (HR 0.013 (95% CI: 0.001-0.121), Wald statistic 14.704 (p < 0.001)), indicating a longer duration of pregnancy with a higher placental to fetal ratio at gestational week 27. The HR of spontaneous delivery also decreased with increasing placental size, but the association was less prominent than the HR associated with placental to fetal ratio (HR 0.997 [95% CI: 0.995-0.999], Wald statistic 7.638 [p = 0.006]). We estimated no association with fetal size (HR 1.001 [95% CI 0.999-1.003], Wald statistic 1.728 [p = 0.189]).

CONCLUSIONS

Our findings suggest that the placental to fetal ratio at gestational week 27 may be an indicator of the remaining duration of pregnancy until the onset of spontaneous labor.

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.

The Potential of Ambroxol as a Panacea for Neonatal Diseases: A Scoping Review

Ambroxol, a commonly used mucolytic agent, has been extensively studied for its clinical effectiveness in managing respiratory conditions in pediatric and adult patients. The existing body of research on ambroxol demonstrates its safety and efficacy. However, its potential role in preventing and treating neonatal diseases still needs to be explored. This scoping review aims to shed light on the unexplored potential of ambroxol, particularly its applications in perinatal and neonatal care. We aim to offer valuable insights for healthcare professionals, researchers, and academics, thus presenting a positive perspective. Key scientific databases such as Google Scholar, PubMed, Cochrane Library, and Europe PMC were meticulously searched for relevant literature on ambroxol in perinatal and neonatal medicine. Gray literature was also surveyed, and the search encompassed all study designs and languages up to June 2024. Furthermore, citations and reference lists of relevant articles were scrutinized to identify additional pertinent literature. Ambroxol has demonstrated promising effects in preventing and managing respiratory distress syndrome (RDS). It can enter the placental circulation and rapidly build up in human lung tissue to a much greater extent than in plasma. It promotes fetal lung maturation, surfactant production, and alveolar expansion. Numerous studies have demonstrated the efficacy of antenatal and postnatal ambroxol in the prevention and treatment of RDS. Ambroxol has the potential to be administered intravenously or through nebulization, offering the hopeful possibility of reducing the high failure rate typically associated with non-invasive ventilation in extremely preterm infants, instilling a sense of hope and optimism about the potential of ambroxol. It also shows potential in treating bronchopulmonary dysplasia, meconium aspiration syndrome, and neonatal infections. Ambroxol has been observed to assist in the closure of patent ductus arteriosus in preterm infants by inhibiting vasodilator agents such as nitric oxide and exerting vasoconstrictive properties. However, these biological actions may raise concerns regarding the potential induction of pulmonary hypertension and an increased risk of necrotizing enterocolitis. The present scoping review also examines the clinical evidence and the potential of ambroxol in reducing the incidence of intraventricular hemorrhage in preterm infants. Ambroxol may have potential analgesic properties in managing neonatal pain, and as it can penetrate the blood-brain barrier, it suggests potential neuroprotective properties. These properties may encompass the modulation of microglial activation and the antagonistic impact on glutamate receptors. Ambroxol's attributes could contribute to a decreased susceptibility to neurological complications and have demonstrated anticonvulsant effects in preclinical studies. While low-to-moderate-quality evidence indicates potential applications of ambroxol in neonatal care, further research is needed to determine the drug's optimal dosing, timing, and safety profiles in this patient population. We need to investigate ambroxol's potential synergistic effects with antenatal steroids. Exploration is required to assess ambroxol's potential in reducing the high failure rate associated with non-invasive respiratory support for RDS. Lastly, comprehensive studies on the long-term neurodevelopmental outcomes of neonates exposed to ambroxol are essential.

Antenatal corticosteroids: an updated assessment of anticipated benefits and potential risks

Antenatal steroid therapy is increasingly central to the obstetrical management of women at imminent risk of preterm birth. For women likely to deliver between 24 and 34 weeks' gestation, antenatal steroid therapy is the standard of care, conferring sizable benefits and few risks in high-resource environments when appropriately targeted. Recent studies have focused on antenatal steroid use in periviable and late preterm populations, and in term cesarean deliveries. As a result, antenatal steroid therapy has now been applied from 22 to 39+6 weeks of estimated gestational age. There is also an increased appreciation that the vast majority of randomized control data informing the use of antenatal steroids are derived from predominantly high-resource, White populations. Accordingly, a sizable amount of work has recently been undertaken to test how to safely use antenatal steroids in low- and middle-resource environments, wherein the often high rates of preterm birth make these low-cost, easily administered interventions an attractive proposition. It is likely underappreciated by the obstetrical and neonatal communities that the overall efficacy of antenatal steroid therapy is highly variable (including when preterm risk is accurately assessed), the treatment regimens used are largely arbitrary, dosing is suprapharmacologic for effect, and the benefit-risk balance is significantly and differentially modified by gestation. It is also very likely that the patients consenting to receive these treatments are similarly unaware of the complex balance of potential benefits and harms. Although a small number of follow-up studies present a generally benign picture of long-term antenatal steroid risk, several large, population-based retrospective studies have identified associations between antenatal steroid use, childhood mental disease, and newborn infections that warrant urgent attention. Of particular contemporary importance are emergent efforts to optimize antenatal steroid regimens on the basis of the pharmacokinetics and pharmacodynamics of the agents themselves, the need for better targeting of these potent drugs, and clear articulation of the potential benefits and harms of antenatal steroid use at differing stages of pregnancy and in different delivery contexts.