Histological chorioamnionitis and developmental outcomes in very preterm infants

The influence of chorioamnionitis on respiratory drive and spontaneous breathing of premature infants at birth: a narrative review

Most very premature infants breathe at birth but require respiratory support in order to stimulate and support their breathing. A significant proportion of premature infants are affected by chorioamnionitis, defined as an umbrella term for antenatal inflammation of the foetal membranes and umbilical vessels. Chorioamnionitis produces inflammatory mediators that potentially depress the respiratory drive generated in the brainstem. Such respiratory depression could maintain itself by delaying lung aeration, hampering respiratory support at birth and putting infants at risk of hypoxic injury. This inflammatory-mediated respiratory depression may contribute to an association between chorioamnionitis and increased requirement of neonatal resuscitation in premature infants at birth. This narrative review summarises mechanisms on how respiratory drive and spontaneous breathing could be influenced by chorioamnionitis and provides possible interventions to stimulate spontaneous breathing.  Conclusion: Chorioamnionitis could possibly depress respiratory drive and spontaneous breathing in premature infants at birth. Interventions to stimulate spontaneous breathing could therefore be valuable. What is Known: • A large proportion of premature infants are affected by chorioamnionitis, antenatal inflammation of the foetal membranes and umbilical vessels. What is New: • Premature infants affected by chorioamnionitis might be exposed to higher concentrations of respiratory drive inhibitors which could depress breathing at birth. • Premature infants affected by chorioamnionitis seem to be associated with a higher and more extensive requirement of resuscitation at birth.

The histologic fetal inflammatory response and neonatal outcomes: systematic review and meta-analysis

OBJECTIVE

This study aimed to investigate the prognostic role of concomitant histological fetal inflammatory response with chorioamnionitis on neonatal outcomes through a systematic review and meta-analysis of existing literature.

DATA SOURCES

The primary search was conducted on October 17, 2021, and it was updated on May 26, 2023, across 4 separate databases (MEDLINE, the Cochrane Central Register of Controlled Trials, Embase, and Scopus) without using any filters.

STUDY ELIGIBILITY CRITERIA

Observational studies reporting obstetrical and neonatal outcomes of infant-mother dyads with histological chorioamnionitis and histological fetal inflammatory response vs infant-mother dyads with histological chorioamnionitis alone were eligible. Studies that enrolled only preterm neonates, studies on neonates born before 37 weeks of gestation, or studies on neonates with very low birthweight (birthweight <1500 g) were included. The protocol was registered with the International Prospective Register of Systematic Reviews (registration number: CRD42021283448).

METHODS

The records were selected by title, abstract, and full text, and disagreements were resolved by consensus. Random-effect model-based pooled odds ratios with corresponding 95% confidence intervals were calculated for dichotomous outcomes.

RESULTS

Overall, 50 studies were identified. A quantitative analysis of 14 outcomes was performed. Subgroup analysis using the mean gestational age of the studies was performed, and a cutoff of 28 weeks of gestation was implemented. Among neonates with lower gestational ages, early-onset sepsis (pooled odds ratio, 2.23; 95% confidence interval, 1.76-2.84) and bronchopulmonary dysplasia (pooled odds ratio, 1.30; 95% confidence interval, 1.02-1.66) were associated with histological fetal inflammatory response. Our analysis showed that preterm neonates with a concomitant histological fetal inflammatory response are more likely to develop intraventricular hemorrhage (pooled odds ratio, 1.54; 95% confidence interval, 1.18-2.02) and retinopathy of prematurity (pooled odds ratio, 1.37; 95% confidence interval, 1.03-1.82). The odds of clinical chorioamnionitis were almost 3-fold higher among infant-mother dyads with histological fetal inflammatory response than among infant-mother dyads with histological chorioamnionitis alone (pooled odds ratio, 2.99; 95% confidence interval, 1.96-4.55).

CONCLUSION

This study investigated multiple neonatal outcomes and found association in the case of 4 major morbidities: early-onset sepsis, bronchopulmonary dysplasia, intraventricular hemorrhage, and retinopathy of prematurity.

Periventricular hemorrhagic infarction in preterm neonates: Etiology and time of development

BACKGROUND

To find the obstetrical and delivery associated risk factors of antenatal and postnatal grade III intraventricular hemorrhage (IVH) or periventricular hemorrhagic infarction (PVHI) in preterm neonates.

METHODS

A retrospective study of obstetric and delivery associated risk factors included neonates (<35 gestational weeks) with severe IVH/PVHI (n = 120) and a prospectively collected control group (n = 50). The children were divided into: (1) antenatal onset group (n = 27) with insult visible on cerebral ultrasonography within the first 12 hours of birth or periventricular cystic changes visible in PVHI within the first 3 days; (2) neonatal onset group (n = 70) with insult diagnosed after initial normal findings or I-II grade IVH, and (3) unknown time-onset group (n = 23) with insult visible at > 12 h of age.

RESULTS

The mothers of the antenatal onset group had significantly more bacterial infections before delivery compared to the neonatal onset group: 20/27 (74.1%) versus 23/69 (33.3%), (odds ratio (OR) 5.7 [95% confidence interval 2.1-16]; p = 0.0008) or compared to the control group (11/50 (22%); OR 11 [2.8-42]; p = 0.0005). Placental histology revealed chorioamnionitis more often in the antenatal compared to the neonatal onset group (14/21 (66.7%) versus 16/42 (38.1%), respectively; OR 3.7 [1.18-11]; p = 0.025). Neonates with neonatal development of severe IVH/PVHI had significantly more complications during delivery or intensive care.

CONCLUSIONS

Bacterial infection during pregnancy is an important risk factor for development of antenatal onset severe IVH or PVHI. In neonates born to mothers with severe bacterial infection during pregnancy, cerebral ultrasonography is indicated for early detection of severe IVH or PVHI.

Outcomes to 5 years of outborn versus inborn infants <32 weeks in Western Australia: a cohort study of infants born between 2005 and 2018

OBJECTIVE

We compared mortality and morbidity of inborn versus outborn very preterm infants <32 weeks' gestation in Western Australia (WA) between 2005 and 2018.

DESIGN

Retrospective cohort study.

PATIENTS

Infants <32 weeks' gestation who were born in WA.

MAIN OUTCOME MEASURES

Mortality was assessed as death before discharge home from the tertiary neonatal intensive care unit. Short-term morbidities included combined brain injury (intracranial haemorrhage grade ≥3 and cystic periventricular leukomalacia) and other major neonatal outcomes. Developmental assessments at age 2, 3 and 5 years were evaluated. We performed multivariable logistic regression analysis of outborn status on outcomes, controlling for gestational age, birth weight z-score, sex and multiple birth.

RESULTS

A total of 4974 infants were born in WA between 22 and 32 weeks' gestation between 2005 and 2018 of which 4237 (89.6%) were inborn and 443 (10.4%) were outborn. Overall mortality to discharge was higher in outborn infants (20.5% (91/443) vs 7.4% (314/4237); adjusted OR (aOR) 2.44, 95% CI 1.60 to 3.70, p<0.001). Outborn infants had higher rates of combined brain injury than those inborn (10.7% (41/384) vs 6.0% (246/4115); aOR 1.98, 95% CI 1.37 to 2.86), p<0.001). No difference in up to 5-year developmental measures was detected. Follow-up data were available for 65% of outborn and 79% of inborn infants.

CONCLUSIONS

Outborn preterm infants <32 weeks in WA had increased odds of mortality and combined brain injury than those inborn. Developmental outcomes up to 5 years were similar between groups. Loss to follow-up may have impacted the long-term comparison.

A retrospective study of risk factors for early-onset neonatal sepsis with intrapartum maternal fever

Background

Intrapartum fever is a well-known risk factor for adverse perinatal outcomes. In this study, we evaluated the clinical features for intrapartum maternal fever and investigated the risk factors for neonatal early-onset sepsis (EOS) with intrapartum maternal fever.

Methods

This retrospective cohort study involved a total of 568 neonates born to mothers with intrapartum maternal fever (temperature peak ≥38 degree Celsius) in Hangzhou Women's Hospital from January 1st to December 31st, 2019. Neonates were assigned to the EOS and non-sepsis groups based on the diagnostic criteria for early-onset neonatal sepsis,. Demographic data, clinical information and laboratory test results were evaluated to assess the risk factors for EOS.

Results

A total of 568 neonates were included in this study, 84 of whom were diagnosed with EOS. The EOS group was significantly different from the non-sepsis group in 11 items including the both white blood cell (WBC) count and C-reactive protein (CRP) level of the mother before delivery (p < 0.05). A logistic regression analysis revealed that a high maternal WBC count before delivery (OR = 3.261, p = 0.019) and a maternal histological chorioamnionitis (HCA) diagnosis (OR = 5.608, p = 0.002) were independent risk factors for EOS. The optimal cut-off value for WBC (before delivery) was 16.75 × 10*⁹/L for EOS, according to receiver operating characteristic analysis (area under curve was 0.821).

Conclusions

Elevated prenatal maternal WBC counts and maternal HCA diagnosis are both independently associated with EOS. Prenatal maternal WBC counts can be used as a sensitive indicator to predict EOS early.

Elevated neutrophil-lymphocyte ratios in extremely preterm neonates with histologic chorioamnionitis

OBJECTIVE

Histologic chorioamnionitis (HCA) is a placental inflammation linked to preterm birth and adverse neonatal outcome. The neutrophil-lymphocyte ratio (NLR) can identify various inflammatory disorders, however its utility in HCA is not clear. Our goal was to examine NLR values and HCA diagnoses in at-risk pregnancies and neonates.

STUDY DESIGN

We retrospectively analyzed the EHR of mothers and preterm (<33 wk GA) neonates with or without HCA (identified by placental histology). The NLR was calculated from complete blood counts in laboring women and in their neonates (0-24 h of life).

RESULT

In 712 consecutive gestations, 50.8% had HCA (26.5% fetal HCA). The neonatal NLR (0-12 h, 13-24 h) predicted fetal HCA better than chance alone (p = 0.01 and 0.002, respectively).

CONCLUSION

Early NLR elevation in preterm neonates is consistent with a diagnosis of fetal HCA. The NLR may identify preterm neonates at risk for HCA-related complications.

Chorioamnionitis and neurodevelopmental outcome in very preterm infants from 2007 to 2017-a population-based study

AIM

The study compares neurodevelopmental outcome at 24 months corrected age of very preterm infants exposed to chorioamnionitis and controls. Peripartal parameters which may influence outcome are also investigated.

METHODS

In this observational population-based study, very preterm infants born between 2007 and 2017 were eligible (n = 466) and included if a histological placental examination and a complete neurodevelopmental assessment (Bayley Scale of Infant Development II or III) (n = 168) were performed. Secondary analyses were calculated to identify peripartal factors that significantly influence mental and psychomotor outcome.

RESULTS

Included infants showed a mean MDI of 91.2 (SD = 20.7) and a mean PDI of 99.4 (SD = 14.8). Infants with (n = 71) and without (n = 97) chorioamnionitis did not statistically differ either with mean MDI (91.8 vs. 90.3 points; p = 0.29) or mean PDI (98.3 vs. 100.9 points; p = 0.81), even after controlling for gestational age, mean APGAR scores and administration of antenatal steroids. Bronchopulmonary dysplasia was identified as the most influential factor for both MDI (p = .024) and PDI (p = .004).

CONCLUSION

We could not find an effect of chorioamnionitis on neurodevelopmental outcome of very preterm infants over an eleven-year period. Analysis shows that postnatal factors have higher impacts than does chorioamnionitis.

Exosomal delivery of NF-κB inhibitor delays LPS-induced preterm birth and modulates fetal immune cell profile in mouse models

Accumulation of immune cells and activation of the pro-inflammatory transcription factor NF-κB in feto-maternal uterine tissues is a key feature of preterm birth (PTB) pathophysiology. Reduction of the fetal inflammatory response and NF-κB activation are key strategies to minimize infection-associated PTB. Therefore, we engineered extracellular vesicles (exosomes) to contain an NF-κB inhibitor, termed super-repressor (SR) IκBα. Treatment with SR exosomes (1 × 1010 per intraperitoneal injection) after lipopolysaccharide (LPS) challenge on gestation day 15 (E15) prolonged gestation by over 24 hours (PTB ≤ E18.5) and reduced maternal inflammation (n ≥ 4). Furthermore, using a transgenic model in which fetal tissues express the red fluorescent protein tdTomato while maternal tissues do not, we report that LPS-induced PTB in mice is associated with influx of fetal innate immune cells, not maternal, into feto-maternal uterine tissues. SR packaged in exosomes provides a stable and specific intervention for reducing the inflammatory response associated with PTB.

Maternal-Fetal Inflammation in the Placenta and the Developmental Origins of Health and Disease

Events in fetal life impact long-term health outcomes. The placenta is the first organ to form and is the site of juxtaposition between the maternal and fetal circulations. Most diseases of pregnancy are caused by, impact, or are reflected in the placenta. The purpose of this review is to describe the main inflammatory processes in the placenta, discuss their immunology, and relate their short- and long-term disease associations. Acute placental inflammation (API), including maternal and fetal inflammatory responses corresponds to the clinical diagnosis of chorioamnionitis and is associated with respiratory and neurodevelopmental diseases. The chronic placental inflammatory pathologies (CPI), include chronic villitis of unknown etiology, chronic deciduitis, chronic chorionitis, eosinophilic T-cell vasculitis, and chronic histiocytic intervillositis. These diseases are less-well studied, but have complex immunology and show mechanistic impacts on the fetal immune system. Overall, much work remains to be done in describing the long-term impacts of placental inflammation on offspring health.

Evidence base multi-discipline critical strategies toward better tomorrow for very preterm infants

Despite advances in neonatal intensive care in the recent decade, a large number of very preterm infants (VPIs) remain at risk for significant neurodevelopmental impairment (NDI). Given that there are many interventions need to be implemented during the critical perinatal period so that complications of these vulnerable VPIs could be minimized, it is urgent to develop multi-discipline strategies based on evidence to be carried out. The objective of this new term evidence-based perinatal critical strategies (EBPCS), is to provide beneficial intervention towards better neurodevelopmental outcomes, specifically for preterm infants below 28 weeks gestational age. EBPCS is defined as the management of the VPIs during the perinatal period which would include antenatal counseling with team briefing and share decision making, treat the chorioamnionitis, antenatal MgS04, antenatal steroid, delayed cord clamping/milking, neonatal resuscitation team preparation, prevention of hypothermia, immediate respiratory support with continuous positive airway pressure at delivery room, less invasive surfactant administration, early surfactant with budesonide therapy, support of cardiovascular system, early initiate of probiotics administration, early caffeine, early parenteral and enteral nutrition, promptly initiating antibiotics. These critical strategies will be discussed detail in the text; nonetheless, standardized protocols, technical skills and repeated training are the cornerstones of successful of EBPCS. Further experience from different NICU is needed to prove whether these very complicate and comprehensive perinatal critical strategies could translate into daily practice to mitigate the incidence of NDI in high-risk VPIs.

Microbial invasion of the amniotic cavity is associated with impaired cognitive and motor function at school age in preterm children

BACKGROUND

Chorioamnionitis is an important cause of preterm delivery. Data on neurodevelopmental outcome in exposed infants are inconsistent due to difficulties in diagnosing intrauterine infection/inflammation and lack of detailed long-term follow-up. We investigate cognitive and motor function in preterm infants at early school age and relate the findings to bacteria in amniotic fluid obtained by amniocentesis (microbial invasion of the amniotic cavity (MIAC)) or placenta findings of histological chorioamnionitis (HCA) or fetal inflammatory response syndrome (FIRS).

METHOD

Sixty-six infants with gestational age <34 weeks at birth and without major disabilities were assessed using WISC-III and the Bruininks-Oseretsky Test of Motor Proficiency. Results were corrected for gestational age and sex.

RESULTS

Children exposed to MIAC had significantly lower scores for full-scale IQ and verbal IQ compared to the non-MIAC group and the difference in full-scale IQ remained after correction for confounding factors. The MIAC group had also significantly lower motor scores after correction. In contrast, motor function was not affected in infants exposed to HCA or FIRS and differences between groups for cognitive scores were lost after corrections.

CONCLUSION

Exposure to bacteria in amniotic fluid is associated with lower motor and cognitive scores in school age preterm infants without major disabilities.

Fetal membrane bacterial load is increased in histologically confirmed inflammatory chorioamnionitis: A retrospective cohort study

INTRODUCTION

It is widely debated whether fetal membranes possess a genuine microbiome, and if bacterial presence and load is linked to inflammation. Chorioamnionitis is an inflammation of the fetal membranes. This research focussed on inflammatory diagnosed histological chorioamnionitis (HCA) and aimed to determine whether the bacterial load in fetal membranes correlates to inflammatory response, including histological staging and inflammatory markers in HCA.

METHODS

Fetal membrane samples were collected from patients with preterm spontaneous labour and histologically phenotyped chorioamnionitis (HCA; n = 12), or preterm (n = 6) and term labour without HCA (n = 6). The bacterial profile of fetal membranes was analysed by sequencing the V4 region of the 16S rRNA gene. Bacterial load was determined using qPCR copy number/mg of tissue. The association between bacterial load and bacterial profile composition was assessed using correlation analysis.

RESULTS

Bacterial load was significantly greater within HCA amnion (p = 0.002) and chorion (p = 0.042), compared to preterm birth without HCA. Increased bacterial load was positively correlated with increased histological staging (p = 0.001) and the expression of five inflammatory markers; IL8, TLR1, TLR2, LY96 and IRAK2 (p=<0.050). Bacterial profiles were significantly different between membranes with and without HCA in amnion (p = 0.012) and chorion (p = 0.001), but no differences between specific genera were detected.

DISCUSSION

Inflammatory HCA is associated with infection and increased bacterial load in a dose response relationship. Bacterial load is positively correlated with HCA severity and the TLR signalling pathway. Further research should investigate the bacterial load threshold required to generate an inflammatory response in HCA.

Association of histological and clinical chorioamnionitis with perinatal and neonatal outcome

Objectives: We investigated the incidence and outcome of clinical and histological chorioamnionitis (CA) and the associated risk factors in an emerging provincial perinatal center in 2014-2015.Study design: Based on the suspected and proven clinical infection in the third trimester of pregnancy, placenta and accessories from singleton deliveries were routinely examined histologically. The incidence of CA and associated fetal and neonatal outcome were compared by the total deliveries.Results: Of the 14,166 deliveries in 12 months, infection and inflammation were found in 373 out of 2372 (15.7%) placentas subjected to histological examination and diagnosed as CA (2.6%). These cases were divided into four groups as histological CA only (HCA, n = 335), clinical and histological CA (HCC, n = 20), clinical CA only (CCA, n = 18) and non-CA control (CON, n = 1999). Thus, an incidence of histological CA was 2.5% (355/14 166) in this birth population. Compared to CON, HCA group was more likely to have premature rupture of membrane, antenatal antibiotic use, gestational age <34 weeks, fetal distress, positive bacterial culture from vaginal secretions, and early-onset sepsis in newborns (all p ≤ .01), which were associated with perinatal risk factors of CA. In the very preterm subgroups, more stillbirths and death at delivery and neonatal intensive care unit admissions (p < .001) were found in the CA group.Conclusions: The results suggested that histological CA was associated with early-onset sepsis and combined perinatal comorbidities which are of more diagnostic importance than clinical only CA. The placental histological examination should be routinely performed in very preterm births to better assess perinatal and neonatal outcome.