Acetaminophen (acetaminophen, APAP), alternatively referred to as paracetamol, is generally accepted as a safe pharmacologic choice to treat pain and fever during pregnancy. This review examines the prevalence and patterns of acetaminophen use during pregnancy and the historical context behind this widespread use. We discuss the emerging and controversial data linking acetaminophen use during pregnancy and adverse effects on the fetus and offspring. Furthermore, we draw on mechanistic evidence from preclinical studies and observational clinical studies that support the hypothesis that in addition to the fetus and newborn, there is a potential impact of acetaminophen on the placenta. We draw on mechanistic data from pre-clinical experiments and observational data from clinical studies to assess the association between APAP exposure and placental cellular injury, preeclampsia, and growth restriction. We conclude that additional research is needed to ensure the most informed pharmacologic management of pain and fever during pregnancy.

Abstract Background While advancements in neonatal intensive care have significantly improved the survival of preterm infants, inflammation-related complications continue to be a major factor in short- and long-term morbidity, especially in the most immature babies. Profound evidence indicates that prenatal and postnatal inflammatory exposures, interacting in a multi-hit sequence, significantly affect both immune responses and long-term organ development. Content While preterm birth frequently represents the initial trigger of an adverse cascade of inflammation, various postnatal environmental factors, such as respiratory support, oxygen therapy, and neonatal infections, contribute to this process, with each event serving as an inflammatory stressor independently associating with inflammation-driven tissue damage. The preterm innate immune system seems particularly susceptible not only to infection, but to pro-inflammatory immune responses and sustained immune activation. Mechanistically, several processes have been implicated, including disturbed homeostasis of inflammatory mediators, antioxidant enzymes, and proteases, as well as altered pathogen recognition, and particularities in the resolution of inflammation. In addition, trained immunity, immune tolerance, epigenetic and metabolic reprogramming, and interactions between altered gut microbiota and the developing immune system may further shape these responses. Subsequently altered, often increased or sustained inflammation has been recognized as a central mechanism linking early-life exposures to impaired lung, brain, gut, and retinal development, and adverse long-term outcomes. The frequency of episodes of inflammation seems to significantly impact the latter. Conclusions A better understanding and greater awareness may enable improved risk stratification and avoidance of inflammatory exposures, and promote the development of more targeted strategies to prevent adverse inflammation during a vulnerable period.

Glucagon activates amino acid catabolism and gluconeogenesis in adults. Elevated glucagon concentrations in the fetus occur in pregnancy complications, such as fetal growth restriction (FGR) and hypoxia, yet the impact of chronic fetal hyperglucagonemia is unknown. Using chronically catheterized pregnant sheep, glucose tracers, and liver tissue biopsies, we investigated the effects of nine days of glucagon infusion at 5 or 50 ng/kg/min in late-gestation fetal sheep that increased plasma glucagon concentrations by 800%. Glucagon-infused fetuses were euglycemic and exhibited lower plasma and hepatic amino acid concentrations. They also had increased hepatic mRNA expression of amino acid catabolism genes, including ARG2, GLS2, BCAT1, BCAT2, GLUL, HAL, UROC1, and PPARGC1A. Metabolite profiling in liver tissue revealed enrichment of pathways associated with amino acid degradation, elevated tri- and diphosphate nucleotides, and changes in fatty acid metabolites, supporting enhanced hepatic energy metabolism from amino acid oxidation. Hepatic glycogen content was reduced in glucagon-infused fetuses and the gluconeogenic genes PCK1 and G6PC1 were increased, although fetal glucose production was not detected. These findings demonstrate that in the fetal liver, chronic hyperglucagonemia activates amino acid catabolic pathways, indicating a physiological role for glucagon in regulating fetal amino acid homeostasis. These findings have implications for understanding fetal hepatic adaptations during chronic fetal hyperglucagonemia that can occur in the setting of FGR or hypoxia.

Fetal growth restriction (FGR) is a severe pregnancy complication often caused by placental insufficiency. Proper trophoblast invasion is essential for placental development and function, ensuring adequate nutrient and oxygen supply to the developing fetus. Dysregulation impairs placental perfusion, leading to FGR. This study uses a calorie-restricted mouse model to investigate genes/molecular mechanisms regulating trophoblast invasion across gestational timepoints. Pregnant mice received either a standard or 50 % calorie-restricted diet from E8.5. Placentas and invasion sites were analyzed at E10.5, E12.5, E14.5, E16.5, and E17.5. mRNA sequencing and RT/qPCR examined trophoblast invasion-related genes (Mmp2, Mmp9, Efna1, Rac1, Rras, Ascl2, Tfap2c, Prl7b1) and angiogenesis genes (Vegfa, Vegfb, Pdgf, Akt3). Immunohistochemistry of trophoblast cells (cytokeratin 8, CK8) and endothelial cell markers (endomucin, CD31, CCD105, VEGFR2) was performed. Statistical analysis used Student's t-test. Caloric restriction significantly reduced fetal/placental weights from E12.5, with persistent growth restriction at E16.5, and E17.5. IHC at E17.5 showed reduced decidual depth, trophoblast invasion distance, and trophoblast quantity within the decidua. This impaired growth was accompanied by reduced expression of trophoblast invasion genes (Mmp2, Mmp9, Efna1, Rac1, Rras, Ascl2, Tfap2c, Prl7b1) in FGR placentas, with a reduction in CK8 trophoblast staining. Angiogenesis reduction in FGR was demonstrated with reduced Vegfa, Vegfb, and Akt3 and supported by reduced CD31, CD105, and VEGF2 endothelial cell markers A caloric-restriction mouse model replicates key FGR pathophysiology, including reduced fetal/placental growth, downregulation of trophoblast invasion genes, impaired trophoblast invasion into the decidua, and reduced placenta angiogenesis. These findings offer molecular insights into placental insufficiency that merits further exploration regarding FGR pathogenesis.

Acetaminophen exposures in the perinatal period are ubiquitous. In addition to being the most commonly used drug during pregnancy, clinicians have increasingly prescribed acetaminophen (APAP) for patients in the neonatal intensive care unit (NICU). Acetaminophen has been shown to reduce post-operative opiate burden and may provide similar efficacy for closure of the patent ductus arteriosus (PDA) as nonsteroidal anti-inflammatory drugs (NSAIDs). However, while APAP exposures have spread to a highly vulnerable population of increasingly less mature infants, robust pharmacokinetic and pharmacodynamic data for APAP are lacking. Concerningly, preclinical studies suggest that perinatal APAP exposures may result in unanticipated adverse effects that are unique to the developing lung. I will discuss the clinical observations linking APAP exposures to adverse respiratory outcomes and the preclinical data demonstrating a developmental susceptibility to APAP-induced lung injury. I will discuss how clinical observations linking perinatal APAP exposures to pulmonary injury have been taken to the bench to produce important insights into the potential mechanisms underlying these findings.

Background: Biliary atresia (BA) is a neonatal fibroinflammatory cholangiopathy of infancy and the most common indication for pediatric liver transplantation. We aimed to define the molecular mechanisms responsible for differences in the rate of disease progression among children with BA. Methods: We performed spatial transcriptomics (ST) analysis on frozen liver tissue at transplant from 14 children: BA with survival with native liver (SNL) <2 years (BA1, n=3), BA with SNL >2 years (BA2, n=4), non-BA cholestasis (n=4), and non-diseased donors (n=3). Transcriptional signatures were compared between patient groups by tissue region (scar, hepatocyte, cholangiocyte). Findings were validated in larger patient cohorts that included BA samples at diagnosis. Results: ST analysis of patients with BA1 showed the most aggressive disease phenotype, characterized by reduced hepatocyte zonation, low expression of homeostatic metabolic signatures, and increased scar heterogeneity enriched for pathways including extracellular matrix remodeling, interferon response, and leukocyte activation. Notably, genes involved in SOX4 hepatocyte-to-cholangiocyte reprogramming were most enriched in patients with BA1. Liver immunohistochemistry with in situ mRNA hybridization showed that patients with BA at diagnosis had increased SOX4 quantification as compared with patients with BA at transplant. Lastly, previously published liver bulk RNA-sequencing data demonstrated higher SOX4 gene-set expression in patients with BA at diagnosis with SNL <2 years. Conclusions: Children with BA and worse outcomes exhibit increased SOX4 gene-set expression at diagnosis with greater loss of hepatocyte zonation and immune-driven scar heterogeneity at transplant. Further mechanistic studies are needed to determine whether SOX4-associated biliary reprogramming contributes to maladaptive reparative processes in BA.

Graphical abstract summarizing the randomized controlled trial of prophylactic acetaminophen (paracetamol) for patent ductus arterosus (PDA) in extremely preterm infants.

Neonates are more susceptible to systemic infections than adults. There is a growing recognition that in adults, the hepatic innate immune response is a key first line of defense against systemic gram-negative bacterial (GNB) infection, such as E. coli. This robust innate immune response will initiate a pro-inflammatory response, activating local and systemic responses, thus mitigating the threat of E. coli and systemic infection. Whether an attenuated hepatic innate immune response contributes to the increased risk of infection in the neonate is unknown. Postnatal day 3 (P3) and adult (6-8 weeks) C57BL/6J (B6) mice were exposed to E. coli (105 CFU/g, IP x 1 and 5 hrs). Hepatic tissue was assessed for neutrophil accumulation [myeloperoxidase (MPO) DAB staining] and E. coli [Colony Forming Units (CFU)]. Hepatic mRNA was assessed for induction of pro-inflammatory primary response genes and Acute Phase proteins (APP) using RT-qPCR. An evaluation of the MPO DAB staining helped determine hepatic neutrophil accumulation and revealed a decrease in baseline recruitment in P3 compared to adult mice. In adults, we expected a gradual increase in hepatic neutrophil recruitment throughout the passing time points. In contrast, hepatic neutrophilic count stayed stagnant in E. coli-exposed neonates. In adults, E. coli hepatic collections had no significant increases throughout the time points. In contrast, consistent with impaired neutrophil recruitment, E. coli burden in P3 mice significantly increases by the 5-hour timepoint. E. coli CFU quantification assessed that P3 mice have a significant growth of E. coli while the CFU for adult mice showed no significant growth. A contributing factor to the recruitment of hepatic neutrophils and E. coli growth in the liver is pro-inflammatory genes. We evaluated common pro-inflammatory genes Il6, Il1𝛽, and Cxcl1, known to express at significant levels in adult mice. In bacteremic adult mice, we observed an increase in the pro-inflammatory genes after 1 hour of E. coli exposure. In contrast, P3 mice do not express the same level of significant expression, and rather demonstrate a delayed initial response. We observed a decrease in hepatic neutrophilic recruitment and significant E. coli growth in the P3 mice coupled with an initial delay in the pro-inflammatory transcriptional response of P3 mice, showing a significant increase at the later 5-hour time point. The APR, activated by the pro-inflammatory transcriptional response, showed a parallel behavior, also exhibiting a delayed and stunted expression of the APR genes Crp, Lbp, and Saa1. In response to systemic GNB infection, the neonatal hepatic innate immune response is attenuated when compared to adults. This includes decreased hepatic neutrophil accumulation, a delay in pro-inflammatory and APR transcription, and increased E. coli growth. We speculate that impaired neonatal hepatic innate immune response to E. coli exposure increases susceptibility to infection.

Acetaminophen (APAP) exposures during human development are common. Emerging epidemiological and experimental evidence links these exposures to subsequent pulmonary morbidity; however, the underlying mechanisms remain incompletely defined. Cell-type-specific expression of the xenobiotic enzyme CYP2E1 is a critical determinant of susceptibility to APAP toxicity. CYP2E1-mediated formation of the reactive metabolite N-acetyl-p-benzoquinone imine (NAPQI) induces mitochondrial injury, which can trigger sterile inflammation through Toll-like receptor 9 (TLR9)-dependent innate immune signaling. The developing mouse lung is particularly vulnerable to APAP exposure at postnatal day 14 (P14), a time point within peak alveologenesis that coincides with maximal pulmonary CYP2E1 expression; however, the role of TLR9 signaling in this developmental window has remained unclear. In a preclinical model, wild-type (WT) and TLR9 knockout (TLR9 KO) male and female mice received a single, nonhepatotoxic dose of APAP (140 mg/kg, ip) at P14. Acute lung injury occurred in both genotypes, but TLR9 deficiency reduced proinflammatory target gene (Il1b, Il6) expression and associated STAT3 activation and target gene (Mmp9, Ptgs2, Cxcl2, Bclxl, Pim1) expression. Although APAP-exposed WT mice demonstrated persistent structural and functional abnormalities at P28, attenuation of the early inflammatory response in TLR9 KO mice preserved lung architecture and pulmonary function. These findings identify TLR9-dependent innate immune activation as a mechanistic link between early-life APAP exposure and impaired lung development. The data further suggest that limiting inflammation during the critical window of alveologenesis may preserve normal lung maturation and reduce later pulmonary morbidity. Further studies are warranted to define the clinical relevance of these findings.NEW & NOTEWORTHY Acute lung injury following acetaminophen (APAP) exposures during the key developmental window of alveologenesis has been previously described. Here, we highlight that eliminating TLR9-mediated immune signaling and associated induction of key proinflammatory mediators attenuated impaired lung development and associated dysfunction. We propose that an underlying mechanism linked with sterile inflammation contributes to abnormal pulmonary development following APAP exposure, and that further investigation is necessary for application in a clinical environment.

BACKGROUND:Paracetamol is increasingly used as analgesic and to treat patent ductus arteriosus (PDA) in preterm infants, though preclinical data suggest it may potentially harm the developing lung. The BeNeDuctus trial compared expectant PDA management versus ibuprofen in infants with gestational age <28 weeks, allowing paracetamol for analgesia. In this secondary analysis of the trial, we investigated the potential association between paracetamol and the risk of bronchopulmonary dysplasia (BPD). METHODS:The 273 infants enrolled in the BeNeDuctus were classified into four subgroups based on their exposure to paracetamol (n = 30), ibuprofen (n = 87), paracetamol and ibuprofen (n = 49), or no exposure (control, n = 107). Multivariable logistic regression was used to calculate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Confounders were selected based on a Directed Acyclic Graph. RESULTS:Compared with the control group, exposure to paracetamol alone (aOR 3.22, CI 1.05-9.89), ibuprofen alone (aOR 2.90, CI 1.40-6.03), or paracetamol and ibuprofen (aOR 3.88, CI 1.57-9.57) was associated with an increased odds of moderate-to-severe BPD. CONCLUSION:Our data suggest that paracetamol, used for pain management, increased the risk of moderate-to-severe BPD. This finding supports the calls for a thorough evaluation of the safety of paracetamol on the developing lungs of extremely preterm infants. IMPACT:Paracetamol is gaining interest as pharmacological treatment for patent ductus arteriosus (PDA) in extremely preterm infants. Safety is assumed, based on data from studies evaluating the effects of paracetamol exposure on liver function, although recently concerns on lung development are emerging. This study supports the urgent need for additional research on the safety of paracetamol as treatment option for PDA, but also for other indications in extremely preterm infants, with regard to lung development.

Whether early-life acetaminophen (APAP) exposures injure the developing lung is controversial. We sought to correlate murine pulmonary developmental expression profiles of Cyp2e1 to susceptibility to APAP exposure. Postnatal day 14 (P14) C57BL/6 mice were exposed to APAP (140 mg/kg × 1 i.p.) and assessed for evidence of a histologic, metabolic, functional, and/or transcriptional pulmonary response. Similar experiments were performed in P14 IL6-/- mice, given the controversial role of IL-6 in APAP-induced tissue injury. No evidence of hepatic injury was noted in APAP-exposed P14 mice. In contrast, within 6 hours of exposure, pulmonary tissue demonstrated histologic and functional evidence of injury and increased mitochondrial load by fluorescence lifetime imaging microscopy. The pulmonary transcriptional response was marked by increased expression of Cyp2e1, Nrf2 targets, and proinflammatory genes. Specifically, APAP exposure increased pulmonary IL-6 mRNA, protein, and associated STAT3 signaling. In contrast, IL6-/- mice demonstrated attenuated STAT3 signaling and injury at 6 hours of exposure. At P28, functional and stereologic assessment of both wild-type and IL6-/- mice exposed to a single dose of APAP at P14 revealed persistent abnormalities consistent with lung enlargement and alveolar simplification. Developmentally regulated surges in pulmonary Cyp2e1 expression correlate with sensitivity to APAP exposures that do not cause recognizable hepatic injury. A single exposure during this developmental window is enough to cause persistent functional and stereological abnormalities. These results highlight the need to further study the relationship between developmentally regulated pulmonary Cyp2e1 expression, APAP exposures, and long-term pulmonary dysfunction.

Extremely preterm birth predisposes infants to bronchopulmonary dysplasia and associated pulmonary hypertension (PH). High altitude exposure during pregnancy has also been shown to worsen infant lung and pulmonary vascular outcomes. Animal models addressing the mechanisms for how maternal hypoxia impacts postnatal and adult lung and pulmonary vascular outcomes are lacking and development of a model to address this gap would enable new mechanistic studies. We hypothesize that late gestational hypoxia disrupts lung and pulmonary vascular development in the offspring, leading to abrupted lung development and PH in adulthood. Pregnant wild-type mice were exposed to hypobaric hypoxia at 505 mmHg, from day 16.5 of gestation until birth. Lung and pulmonary vascular outcomes were measured in juvenile and mature offspring. We found that late gestational hypoxia resulted in abrupted alveolar and pulmonary vascular development in juvenile offspring and that adult offspring showed persistent abrupted alveolar development as well as PH. This striking model will provide a new opportunity to determine mechanisms responsible for poor outcomes secondary to maternal hypoxia and assess important factors that increase susceptibility to adult diseases in former preterm infants.

Background/Objectives: Acetaminophen (APAP) is used during 50–60% of pregnancies in the U.S. and has been associated with childhood respiratory morbidity, though the underlying mechanism remains unclear. APAP-induced injury is dependent on cell-specific expression of CYP2E1, the enzyme that metabolizes APAP into the mitochondrial toxin NAPQI. In mice, pulmonary Cyp2e1 expression peaks during the saccular stage of lung development on embryonic day 18 (E18). We investigated whether this developmental surge in Cyp2e1 triggers a pulmonary transcriptional response to maternal APAP exposure in embryonic lungs. Methods: Pregnant dams were exposed to APAP on E17 or E18 (150 or 250 mg/kg, IP) using doses derived from prior studies. We assessed the induction of NRF2 target genes and genes associated with inflammation, apoptosis and cellular stress due to their roles in APAP-induced oxidative and cellular stress. Results: At E17, maternal treatment with APAP induced pulmonary Cyp2e1 but resulted in inconsistent transcriptional changes. In contrast, maternal APAP at E18 triggered a robust transcriptional induction of Cyp2e1, NRF2 targets and markers of apoptosis, inflammation and cellular stress. Histopathology at birth after E18 APAP exposure revealed no acute pulmonary injury. Conclusions: We demonstrate a developmentally regulated, dose-dependent transcriptional response to maternal APAP in the embryonic murine lung. Importantly, transcriptional responses do not directly indicate lung injury; thus, future studies should assess protein-level changes following APAP exposure. This study underscores the need for further investigation into the role of developmentally regulated Cyp2e1 expression in APAP-induced toxicity and long-term respiratory morbidity.

Objectives: Maternal malnutrition during pregnancy results in developmental programing of offspring that increases risk for later metabolic disease. The offspring's diet further influences these risks, but less is known about the interactions of prenatal and postnatal nutrition exposures into adulthood. Methods: Pregnant C57BL/6J mice were randomized to 30% calorie restriction (CR) or ad libitum food (control) starting at day 10 of gestation. At 21 days of life, offspring were weaned to control (CON, 7% calories from fat) or HFD (45% calories from fat) diet. At age 16-18 weeks, female and male control and CR offspring (n = 6/group) were euthanized. Whole livers were collected, weighed, and flash frozen. mRNA-sequencing was conducted using Illumina methodology. Differentially regulated genes (DEGs) were defined using the limma-voom pipeline as ±1.2-fold change and adjusted p < 0.1. Pathways represented by up- and down-regulated DEGs were identified using Enrichr. Expression of individual genes of interest were compared by fetal growth and postnatal diet by two-way ANOVA. Results: At day 18.5, CR fetuses weighed an average of 19% less than controls, but did not differ at age 16 weeks within diet groups. Relative liver weight also did not differ between groups. Among females, no genes had padj < 0.01 (n = 1,065 with p < 0.05). Comparing CR to control males, there were 5,844 DEGs for those fed CON-diet, and 153 for those fed HFD. The top upregulated pathways in CR-CON livers related to cell cycle and inflammation. Top upregulated pathways in CR-HFD related to fatty acid degradation including PPAR signaling. Expression of PPARγ, a regulator of hepatic lipid metabolism, was 4-fold higher (p = 0.0014) in CR-CON male livers. Expression of PPARα, which is involved in regulation of fatty acid oxidation and triglyceride levels, was 1.5-fold lower in CR-CON male livers. TNFα expression was higher 6.8-fold higher in CR-CON versus control-CON males. Conclusions: Maternal calorie restriction resulted in substantial differences in hepatic gene expression related to fatty acid metabolism, insulin sensitivity, and inflammation in adult male offspring. Additional work is needed to determine a mechanistic role for these changes in metabolic outcomes. Funding Sources: NIDDK, Ludeman Family Center for Women's Health Research.

BackgroundMaternal undernutrition is the most common cause of fetal growth restriction (FGR) worldwide. FGR increases morbidity and mortality during infancy, as well as contributes to adult-onset diseases including obesity and type 2 diabetes. The role of the maternal or offspring microbiome in growth outcomes following FGR is not well understood.MethodsFGR was induced by 30% maternal calorie restriction (CR) during the second half of gestation in C57BL/6 mice. Pup weights were obtained on day of life 0, 1, and 7 and ages 3, 4 and 16 weeks. Fecal pellets were collected from pregnant dams at gestational day 18.5 and from offspring at ages 3 and 4 weeks of age. Bacterial genomic DNA was used for amplification of the V4 variable region of the 16S rRNA gene. Multivariable associations between maternal CR and taxonomic abundance were assessed using the MaAsLin2 package. Associations between microbial taxa and offspring outcomes were performed using distance-based redundancy analysis and Pearson correlations.ResultsFGR pups weighed about 20% less than controls. Beta but not alpha diversity differed between control and CR dam microbiomes. CR dams had lower relative abundance of Turicibacter, Flexispira, and Rikenella, and increased relative abundance of Parabacteroides and Prevotella. Control and FGR offspring microbiota differed by beta diversity at ages 3 and 4 weeks. At 3 weeks, FGR offspring had decreased relative abundance of Akkermansia and Sutterella and increased relative abundance of Anaerostipes and Paraprevotella. At 4 weeks, FGR animals had decreased relative abundance of Allobaculum, Sutterella, Bifidobacterium, and Lactobacillus, among others, and increased relative abundance of Turcibacter, Dorea, and Roseburia. Maternal Helicobacter abundance was positively associated with offspring weight. Akkermansia abundance at age 3 and 4 weeks was negatively associated with adult weight.ConclusionsWe demonstrate gut microbial dysbiosis in pregnant dams and offspring at two timepoints following maternal calorie restriction. Additional research is needed to test for functional roles of the microbiome in offspring growth outcomes.

OBJECTIVE Emerging data indicate that acetaminophen may adversely affect lung health. We examined whether acetaminophen compared with cyclooxygenase (COX) inhibitor alone for patent ductus arteriosus (PDA) is associated with mortality or respiratory morbidity in extremely preterm infants.METHODS This is a retrospective cohort study using data from the National Institute of Child Health and Human Development Neonatal Research Network. Infants were born at 22 to 28 weeks' gestation or weighing 401 to 1000 g between 2016 and 2020 and received acetaminophen, ibuprofen, and/or indomethacin for PDA closure. The primary outcome was death or grade 2 to 3 bronchopulmonary dysplasia (BPD) at 36 weeks' postmenstrual age. Secondary outcomes included predischarge mortality and respiratory morbidities. Risk ratios were adjusted for baseline and early postnatal factors. Additional exploratory analyses were adjusted for later postnatal covariates.RESULTS Of 1921 infants, 627 (32.6%) received acetaminophen and 1294 (67.3%) received COX inhibitor only. Multidrug therapy (42.9% vs 4.7%) and surgical or catheter PDA closure (26.5% vs 19.9%) were more common among acetaminophen-exposed infants. Death or grade 2 to 3 BPD at 36 weeks' postmenstrual age was similar between infants treated with acetaminophen versus COX inhibitor only (57.1% vs 58.3%; adjusted relative risk [aRR] 0.96, 95% confidence interval [CI] 0.87-1.06). Acetaminophen was associated with increased risk of predischarge mortality (13.3% vs 10.0%) when adjusting for perinatal and early postnatal factors (aRR 1.42, 95% CI 1.02-1.93), but not in exploratory analyses that included later postnatal factors (aRR 1.28, 95% CI 0.91-1.82).CONCLUSIONS Treatment with acetaminophen versus COX inhibitor alone for PDA was not associated with the composite outcome of death or BPD in extremely preterm infants. Our results support further evaluation of whether acetaminophen for PDA increases mortality.

Background The Neonatal Oxygenation Prospective Meta-analysis found that in infants <28 weeks gestational age, targeting an oxygen saturation (SpO2) range of 85–89% versus 91–95% resulted in lower rates of retinopathy of prematurity but increased mortality. We aimed to evaluate the accuracy of the heart rate characteristics index (HRCi) in assessing the dynamic risk of mortality among infants managed with low and high target SpO2 ranges. Methods We linked the SUPPORT and HRCi datasets from one centre in which the randomised controlled trials overlapped. We examined the maximum daily HRCi (MaxHRCi24) to predict mortality among patients randomised to the lower and higher target SpO2 groups by generating predictiveness curves and calculating model performance metrics, including area under the receiver operating characteristics curve (AUROC) at prediction windows from 1–60 days. Cox proportional hazards models tested whether MaxHRCi24 was an independent predictor of mortality. We also conducted a moderation analysis. Results There were 84 infants in the merged dataset. MaxHRCi24 predicted mortality in infants randomised to the lower target SpO2 (AUROC of 0.79–0.89 depending upon the prediction window) and higher target SpO2 (AUROC 0.82–0.91). MaxHRCi24 was an important additional predictor of mortality in multivariable modelling. In moderation analysis, in a model that also included demographic predictor variables, the individual terms and the interaction term between MaxHRCi24 and target SpO2 range all predicted mortality. Conclusions Associations between HRCi and mortality, at low and high SpO2 target ranges, suggest that future research may find HRCi metrics helpful to individually optimise target oxygen saturation ranges for hospitalised preterm infants.

Maintenance of hepatocyte homeostasis plays an important role in controlling the pathogenesis of many diseases. Our findings add to a growing body of literature on tumor necrosis factor-α (TNFα)-mediated hepatocyte homeostasis and identify novel molecular mechanisms involved in regulating this response.