Acute and Chronic Placental Abnormalities in a Multicenter Cohort of Newborn Infants with Hypoxic-Ischemic Encephalopathy

Placental inflammatory response and association with the severity of neonatal hypoxic ischemic encephalopathy

BACKGROUND

Placental lesions are associated with worse neonatal outcomes, but their association with neonatal hypoxic-ischemic encephalopathy (HIE), including the full range of severity from mild to severe HIE, has not been well described.

OBJECTIVE

To determine the association of acute and chronic placental lesions with mild versus moderate to severe HIE; secondarily, to assess the impact of multiple placental lesions on severity of HIE.

METHODS

This retrospective study of prospectively collected data included neonates born at ≥36 weeks, with a birth weight of >1800 g, diagnosed with HIE between January 2012 and November 2022. The cohort was divided into those with mild versus moderate to severe HIE, based on the modified Sarnat staging. Placental histologic diagnoses were made according to the Amsterdam Placental Workshop Group Consensus Statement. Placental pathologic lesions were classified into acute inflammation with attention to stages and grades of maternal and fetal inflammatory responses (MIR and FIR, respectively), maternal vascular malperfusion, fetal vascular malperfusion, villitis of unknown etiology, and other lesions. Chi-square and Fisher's exact test were used to compare rates of placental pathologies between mild and moderate to severe HIE groups.

RESULTS

Of 394 neonates ≥36 weeks' gestation diagnosed with HIE, 172 had mild HIE and received supportive care, while 180 had moderate to severe HIE and underwent therapeutic hypothermia. 42 patients were excluded due to lack of placental pathology reports. FIR was significantly associated with moderate to severe HIE vs. mild HIE (53 % vs. 38 %, P < 0.01). Higher grade and stage of FIR was also associated with worse severity of HIE (moderate to severe HIE showed FIR stage ≥2 in 81 % and grade 2 in 15 % vs. 34 % and 3 % in those with mild HIE, respectively). MIR was diagnosed in more placentas from the moderate to severe HIE group (58 % vs. 47 %, P = 0.04) with higher stage and grade MIR in patients with moderate to severe HIE (86 % with MIR stage ≥2 and 19 % with MIR grade 2). High-grade (patchy/diffuse) chronic villitis was more prevalent in the moderate to severe HIE group vs. mild HIE group (18 % vs. 8 %, P < 0.01).

CONCLUSION

There is a higher prevalence of placental inflammatory lesions in neonates with moderate to severe HIE compared to those with mild HIE.

Uncovering the Role of Inflammation with Asphyxia in the Newborn

The etiology of perinatal brain injury is multifactorial, but exposure to perinatal hypoxiaischemia (HI) is a major underlying factor. This review discusses the role of exposure to infection/inflammation in the evolution of HI brain injury, changes in immune responsiveness to subsequent inflammatory challenges after HI and modulation of neural outcomes with interaction between perinatal HI and inflammatory insults. The authors critically assess the clinical and preclinical evidence for the neuroprotective efficacy of therapeutic hypothermia and other anti-inflammatory treatments for inflammation-sensitized HI injury.

Causes and Terminology in Neonatal Encephalopathy: What is in a Name? Neonatal Encephalopathy, Hypoxic-ischemic Encephalopathy or Perinatal Asphyxia

Neurologic depression in term/near-term neonates (neonatal encephalopathy, NE) is uncommon with modern obstetric care. Asphyxial birth, with or without co-factors, accounts for a minority of NE, while maldevelopment (congenital malformations, growth aberrations, genetic, metabolic and placental abnormalities) plays an enlarging role in identifying etiologic subgroups of NE. The terms NE and hypoxic-ischemic encephalopathy (HIE) have not been employed uniformly, hampering research and clinical care. The authors propose the term NE as an early working-diagnosis, to be supplemented by a diagnosis of NE due to HIE or to other factors, as a final diagnosis once workup is complete.

[Investigation of a French cohort of neonatal anoxo-ischemic encephalopathy in the era of therapeutic hypothermia: Questions and answers]

OBJECTIVE

To improve knowledge of neonatal hypoxic-ischemic encephalopathy, a prospective, nationwide, population-based cohort of affected children is being set up between September 2015 and March 2017.

METHODS

During this period, 794 cases are collected, with information on pregnancy, delivery, neonatal stay and outcome at the end of hospitalization. Clinical and parental questionnaire follow-up is planned until the child is 4 years old.

RESULTS

This article presents the clinical presentation of the newborns included, the analysis of factors associated with short-term outcome at hospital discharge and the organizational factors associated with treatment with therapeutic hypothermia.

CONCLUSION

These data illustrate the value of a prospective cohort to analyze the management of anoxo-ischemic encephalopathy in France.

Association of Placental Pathology with Physical and Neuronal Development of Infants: A Narrative Review and Reclassification of the Literature by the Consensus Statement of the Amsterdam Placental Workshop Group

The placenta is the largest fetal organ, which connects the mother to the fetus and supports most aspects of organogenesis through the transport of nutrients and gases. However, further studies are needed to assess placental pathology as a reliable predictor of long-term physical growth or neural development in newborns. The Consensus Statement of the Amsterdam Placental Workshop Group (APWGCS) on the sampling and definition of placental lesions has resulted in diagnostic uniformity in describing the most common pathological lesions of the placenta and contributed to the international standardization of descriptions of placental pathology. In this narrative review, we reclassified descriptions of placental pathology from previously published papers according to the APWGCS criteria and comparatively assessed the relationship with infantile physical and/or neural development. After reclassification and reevaluation, placental pathology of maternal vascular malperfusion, one of the APWGCS criteria, emerged as a promising candidate as a universal predictor of negative infantile neurodevelopmental outcomes, not only in term and preterm deliveries but also in high-risk groups of very low birthweight newborns. However, there are few studies that examined placental pathology according to the full categories of APWGCS and also included low-risk general infants. It is necessary to incorporate the assessment of placental pathology utilizing APWGCS in the design of future birth cohort studies as well as in follow-up investigations of high-risk infants.

Gross and Histologic Placental Abnormalities Associated With Neonatal Hypoxic-Ischemic Encephalopathy

OBJECTIVE

To elucidate particular placental pathology findings that are associated with hypoxic ischemic encephalopathy (HIE) and determine which patterns are associated with adverse fetal/neonatal outcomes.

STUDY DESIGN

Multi-institutional retrospective case-control study of newborns with HIE (2002-2022) and controls. Four perinatal pathologists performed gross and histologic evaluation of placentas of cases and controls.

RESULTS

A total of 265 placentas of neonates with HIE and 122 controls were examined. Infants with HIE were more likely to have anatomic umbilical cord abnormalities (19.7% vs 7.4%, P = .003), fetal inflammatory response in the setting of amniotic fluid infection (27.7% vs 13.9%, P = .004), and fetal vascular malperfusion (30.6% vs 9.0%, P = <.001) versus controls. Fetal vascular malperfusion with maternal vascular malperfusion was more common in those who died of disease (P = .01).

CONCLUSION

Placental pathology examination of neonates with HIE may improve our understanding of this disorder and its adverse outcomes.

The Placenta and Neonatal Encephalopathy with a Focus on Hypoxic-Ischemic Encephalopathy

Background: Placental examination is important for its diagnostic immediacy to correlate with maternal and/or fetal complications and parturitional difficulties. In a broader context, clinicopathologic studies of the placenta have addressed a range of pathogenetic questions that have led to conclusive and inconclusive results and interpretations. Methods: Recent standardized morphologic criteria and terminology of placental lesions have facilitated the ability to compare findings from studies that have focused on complications and outcomes of pregnancy. This review is an evaluation of recent studies on placental lesions associated with hypoxic-ischemic encephalopathy (HIE). Conclusion: No apparent consensus exists on whether it is fetal inflammation with the release of cytokines or chronic maternal and/or fetal vascular malperfusion is responsible for HIE with a lowering of the threshold for hypoxic ischemia. The counter argument is that HIE occurs solely as an intrapartum event. Additional investigation is necessary.

The impact of placental genomic risk for schizophrenia and birth asphyxia on brain development

The placenta plays a role in fetal brain development, and pregnancy and birth complications can be signs of placental dysfunction. Birth asphyxia is associated with smaller head size and higher risk of developing schizophrenia (SZ), but whether birth asphyxia and placental genomic risk factors associated with SZ are related and how they might impact brain development is unclear. 433 adult patients with SZ and 870 healthy controls were clinically evaluated and underwent brain magnetic resonance imaging. Pregnancy and birth information were obtained from the Medical Birth Registry of Norway. Polygenic risk scores (PRS) from the latest genome-wide association study in SZ were differentiated into placental PRS (PlacPRS) and non-placental PRS. If the interaction between PRSs and birth asphyxia on case-control status was significant, neonatal head circumference (nHC) and adult intracranial volume (ICV) were further evaluated with these variables using multiple regression. PlacPRS in individuals with a history of birth asphyxia was associated with a higher likelihood of being a patient with SZ (t = 2.10, p = 0.018). We found a significant interaction between PlacPRS and birth asphyxia on nHC in the whole sample (t = -2.43, p = 0.008), with higher placental PRS for SZ associated with lower nHC in those with birth asphyxia. This relationship was specific to males (t = -2.71, p = 0.005) and also found with their adult ICV (t = -1.97, p = 0.028). These findings suggest that placental pathophysiology and birth asphyxia may affect early and late trajectories of brain development, particularly in males with a higher vulnerability to SZ. This knowledge might lead to new strategies of treatment and prevention in SZ.

The association of placental pathology and neurodevelopmental outcomes in patients with neonatal encephalopathy

BACKGROUND

Studies conflict on how acute versus chronic placental pathology impacts outcomes after neonatal encephalopathy from presumed hypoxic-ischemic encephalopathy (HIE). We examine how outcomes after presumed HIE vary by placental pathology categories.

METHODS

We performed retrospective chart review for neonates with presumed HIE, regardless of severity, focusing on 50 triads for whom placental specimens were available for re-review. Placentas were categorized as having only acute, any chronic, or no lesions. Primary outcomes included in-hospital morbidity/mortality and long-term neurodevelopmental symptoms. Secondary outcomes assessed neonatal MRI and EEG.

RESULTS

Demographics did not differ between groups. Forty-seven neonates were treated with therapeutic hypothermia. Placental acuity category was not associated with primary or secondary outcomes, but clinical and/or histopathological chorioamnionitis was associated with abnormal EEG background and post-neonatal epilepsy (16.7%, n = 3 with chorioamnionitis versus 0%, n = 0 without chorioamnionitis, p = 0.04).

CONCLUSIONS

When grouped by acute, chronic, or absent placental lesions, we observed no association with in-hospital, neurodevelopmental, MRI, or EEG outcomes. When reanalyzed by the presence of chorioamnionitis, we found that chorioamnionitis appeared to be associated with a higher risk of EEG alterations and post-neonatal epilepsy. Despite our limited sample size, our results emphasize the critical role of placental examination for neuroprognostication in presumed HIE.

IMPACT

Neonatal encephalopathy presumed to result from impaired fetal cerebral oxygenation or blood flow is called hypoxic ischemic encephalopathy (HIE). Prior studies link placental pathology to various outcomes after HIE but disagree on the impact of acute versus chronic pathology. Our study determines that neurodevelopmental outcomes, in-hospital outcomes, injury on MRI, and EEG findings in patients with HIE are not differentially associated with acute versus chronic placental pathology. Chorioamnionitis is associated with an increased risk of abnormal EEG patterns and post-neonatal epilepsy. Histopathologic chorioamnionitis without clinical symptoms is common in HIE, emphasizing the crucial role of placental pathology for neuroprognostication.

An Update of Our Understanding of Fetal Heart Rate Patterns in Health and Disease

UNDERSTANDING FETAL HEART RATE PATTERNS THAT MAY PREDICT ANTENATAL AND INTRAPARTUM NEURAL INJURY: Christopher A. Lear, Jenny A. Westgate, Austin Ugwumadu, Jan G. Nijhuis, Peter R. Stone, Antoniya Georgieva, Tomoaki Ikeda, Guido Wassink , Laura Bennet , Alistair J. Gunn Seminars in Pediatric Neurology Volume 28, December 2018, Pages 3-16 Electronic fetal heart rate (FHR) monitoring is widely used to assess fetal well-being throughout pregnancy and labor. Both antenatal and intrapartum FHR monitoring are associated with a high negative predictive value and a very poor positive predictive value. This in part reflects the physiological resilience of the healthy fetus and the remarkable effectiveness of fetal adaptations to even severe challenges. In this way, the majority of "abnormal" FHR patterns in fact reflect a fetus' appropriate adaptive responses to adverse in utero conditions. Understanding the physiology of these adaptations, how they are reflected in the FHR trace and in what conditions they can fail is therefore critical to appreciating both the potential uses and limitations of electronic FHR monitoring.

Placental Pathology and Its Importance in Preterm Infants

OBJECTIVE

We evaluated what placental pathologies were associated with adverse preterm births.

MATERIALS AND METHODS

Placental findings, classified according to the Amsterdam criteria, were correlated with infant outcomes. The fetal vascular lesions, inflammatory responses other than histological chorioamnionitis (HCA), and placentas with combined maternal vascular malperfusion (MVM) and HCA were excluded.

RESULTS

A total of 772 placentas were evaluated. MVM was present in 394 placentas, HCA in 378. Early neonatal sepsis, retinopathy of prematurity, necrotizing enterocolitis, and neonatal death occurred more often in the MVM-only group than HCA-only group. The frequency of bronchopulmonary dysplasia (BPD) was 38.6% in the HCA-only group, and it was 20.3% in the MVM-only group (p < 0.001). HCA was the most important independent risk factor for BPD (OR 3.877, 95% CI 2.831-5.312).

CONCLUSION

Inflammation in the placenta influences fetal and neonatal outcomes. HCA is an independent risk factor for BPD.

Placental Histologic Abnormalities and 2-Year Outcomes in Neonatal Hypoxic-Ischemic Encephalopathy

OBJECTIVE

We aimed to examine the association between placental abnormalities and neurodevelopmental outcomes in a multicenter cohort of newborn infants with hypoxic-ischemic encephalopathy (HIE) that underwent therapeutic hypothermia. We hypothesized that subjects with acute placental abnormalities would have reduced risk of death or neurodevelopmental impairment (NDI) at 2 years of age after undergoing therapeutic hypothermia compared to subjects without acute placental changes.

STUDY DESIGN

Among 500 subjects born at ≥36 weeks gestation with moderate or severe HIE enrolled in the High-dose Erythropoietin for Asphyxia and Encephalopathy (HEAL) Trial, a placental pathologist blinded to clinical information reviewed clinical pathology reports to determine the presence of acute only, chronic only, or both acute and chronic histologic abnormalities. We calculated adjusted relative risks (aRRs) for associations between placental pathologic abnormalities and death or NDI at age 2 years, adjusting for HIE severity, treatment assignment, and site.

RESULT

321/500 subjects (64%) had available placental pathology reports. Placental abnormalities were characterized as acute only (20%), chronic only (21%), both acute and chronic (43%), and none (15%). The risk of death or NDI was not statistically different between subjects with and without an acute placental abnormality (46 vs. 53%, aRR 1.1, 95% confidence interval (CI): 0.9, 1.4). Subjects with two or more chronic lesions were more likely to have an adverse outcome than subjects with no chronic abnormalities, though this did not reach statistical significance (55 vs. 45%, aRR 1.24, 95% CI: 0.99, 1.56).

CONCLUSION

Placental pathologic findings were not independently associated with risk of death or NDI in subjects with HIE. The relationship between multiple chronic placental lesions and HIE outcomes deserves further study.

Leveraging the placenta to advance neonatal care

The impact of placental dysfunction and placental injury on the fetus and newborn infant has become a topic of growing interest in neonatal disease research. However, the use of placental pathology in directing or influencing neonatal clinical management continues to be limited for a wide range of reasons, some of which are historical and thus easily overcome today. In this review, we summarize the most recent literature linking placental function to neonatal outcomes, focusing on clinical placental pathology findings and the most common neonatal diagnoses that have been associated with placental dysfunction. We discuss how recent technological advances in neonatal and perinatal medicine may allow us to make a paradigm shift, in which valuable information provided by the placenta could be used to guide neonatal management more effectively, and to ultimately enhance neonatal care in order to improve our patient outcomes. We propose new avenues of clinical management in which the placenta could serve as a diagnostic tool toward more personalized neonatal intensive care unit management.

Perinatal brain damage - what the obstetrician needs to know

Perinatal brain damage is still one of the leading contributors to perinatal death and postnatal disability worldwide. However, the term perinatal brain damage encompasses very different aetiological entities that result in an insult to the developing brain and does not differentiate between the onset, cause and severity of this insult. Hypoxic-ischemic encephalopathy (HIE), intraventricular haemorrhage, periventricular leukomalacia and perinatal stroke are often listed as the major aetiologies of perinatal brain damage. They differ by type and timing of injury, neuropathological and imaging findings and their clinical picture. Along the timeline of neurodevelopment in utero, there appears to be a specific "window of vulnerability" for each type of injury, but clinical overlap does exist. In the past, peripartum acute hypoxia was believed to be the major, if not the only, cause of perinatal brain damage, but intrauterine inflammation, prematurity, chronic hypoxia/growth retardation and genetic abnormalities appear to be at least equally important contributors.

Placental pathology associated with lenticulostriate vasculopathy (LSV) in preterm infants

OBJECTIVE

Our aim was to examine the frequency and type of placental abnormalities in neonates with LSV.

STUDY DESIGN

We prospectively reviewed cranial ultrasounds (cUS) from neonates born at ≤32 weeks of gestation at Parkland Hospital between 2012 and 2014. Our cohort included neonates with LSV and gestational age and sex matched controls with normal cUS. We retrieved placental pathology reports retrospectively and compared placental abnormalities in both groups.

RESULTS

We reviewed 1351 cUS from a total of 407 neonates. Placental pathology evaluations were complete for 64/65 (98%) neonates with LSV and 68/70 (97%) matched controls. There were no significant differences for any type of placental abnormities between LSV and control groups. However, infants with highest stage LSV were more likely to have large for gestational age (LGA) placentas (p = 0.01).

CONCLUSION

The association between LSV and LGA placenta may indicate a shared vascular response to an adverse prenatal environment.

Placental pathology as a marker of brain injury in infants with hypoxic ischemic encephalopathy

BACKGROUND

Hypoxic Ischemic Encephalopathy (HIE) can lead to devastating consequences for the affected infant. Although therapeutic cooling benefits infants with moderate and severe HIE, differentiating mild from moderate-severe HIE may be challenging. The placenta reflects the fetal intrauterine environment and may reveal underlying processes that affect brain injury.

AIM

To describe placental histopathology using the Amsterdam Placental Workshop Group Criteria in different grades of HIE.

STUDY DESIGN

Retrospective cohort.

SUBJECTS

Infants admitted to a tertiary care neonatal intensive care unit with a diagnosis of HIE between 2011 and 2016.

OUTCOME MEASURE

Maternal and neonatal clinical variables and placental histopathology using the Amsterdam Placental Workshop Group Criteria were compared between mild and moderate-severe HIE. Mann-Whitney or t-test or ꭓ² were performed for bivariate associations as appropriate. To explain the relationship between placental pathology and severity of HIE odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated using logistic regression models.

RESULTS

Of the 73 infants in the study, 23 had mild and 50 moderate-sever HIE. There was no difference in maternal and neonatal characteristics except for sentinel events which were higher in the moderate- severe group. On placental histopathology, acute inflammation, including fetal inflammatory reaction (FIR) were significantly higher in the moderate-severe group. After adjusting for confounders, FIR remained significantly associated with moderate-severe HIE, ORs 6.29, 95 % CI 1.5-25.

CONCLUSION

Our study demonstrates FIR in the placenta is associated with severity of HIE.

Relationship Between Placental Weight and Placental Pathology With MRI Findings in Mild to Moderate Hypoxic Ischemic Encephalopathy

Introduction

The placenta plays a critical role in fetal growth and development. Examination of the placenta may provide information on the timing and extent of adverse prenatal and perinatal events. Multiple studies demonstrate an association between placental changes and hypoxic-ischemic encephalopathy (HIE), but there are limited data on the association between placental pathology and MRI changes in HIE. This study assesses the relationship between placental pathology and MRI abnormalities in infants with HIE after receiving therapeutic hypothermia.

Methods

A retrospective study of 138 full-term infants who underwent therapeutic hypothermia for HIE at a single delivery center. Using logistic regression models, placental pathology and MRI results were analyzed to determine if placental abnormalities are associated with more significant MRI abnormalities. Placentas matched by gestational age and birthweight from a sample of convenience were included for comparison.

Results

Of the 138 infants who underwent therapeutic hypothermia for HIE, 84 had placental pathology and MRIs available. Of these, 30 had normal, and 54 had abnormal MRIs. Placental changes are not observed more frequently in the HIE cohort with abnormal MRI. Increased placenta weight: birthweight ratio is independently associated with increased odds of moderate-severe HIE compared to a convenient sample.

Conclusion

In a study sample of babies with HIE, placental pathology was not associated with subsequent abnormal MRI findings. Compared to matched controls, babies with HIE had an elevation in placental weight/birthweight.

Placental Findings in Infants with Hypoxic-Ischemic Encephalopathy: The Importance of the Comparison Group

OBJECTIVE

To determine the effect of 3 distinct comparison groups on associations between placental abnormalities and neonatal hypoxic-ischemic encephalopathy (HIE).

STUDY DESIGN

This single-center, prospective case-control study of singletons of gestational age ≥36 weeks with predefined criteria for HIE (n = 30) and 3 control groups was conducted from June 2015 to January 2018. The control groups were infants born by repeat cesarean delivery (n = 60), infants born small for gestational age (SGA; n = 80), and infants receiving positive-pressure ventilation (PPV) at birth (n = 70). One pathologist blinded to infant category reviewed placental sections using the Amsterdam Placental Workshop criteria. Logistic regression with group contrasts relative to HIE was used to analyze primary placental pathologies, and ORs with 95% CIs provided effect sizes.

RESULTS

The odds of maternal vascular malperfusion were increased among HIE group placentas compared with placentas of the repeat cesarean delivery (OR, 4.50; 95% CI, 1.45-14.00) and PPV (3.88; 1.35-11.16) groups, but not those of the SGA group. The odds of fetal vascular malperfusion were increased in the HIE group compared with the SGA group (OR, 9.75; 95% CI, 1.85-51.51). The odds of acute chorioamnionitis were higher in the HIE group compared only with the repeat cesarean delivery group, reflecting a similar incidence of chorioamnionitis in SGA group and PPV group placentas. The absence of placental findings was lowest in the HIE group (6.7%), followed by the SGA (18.8%), PPV (31.4%), and repeat cesarean delivery (75%) groups.

CONCLUSIONS

Associations with placental abnormalities among infants with HIE varied based on the specific placental abnormality and the control group. Potentially important associations between placental pathology and HIE may be obscured if control groups are not well designed.

Distinctive Neuroimaging Pattern in Term Newborns With Neonatal Placental Encephalopathy: A Case Series

BACKGROUND

Identifying antepartum versus intrapartum timing and the cause of neonatal encephalopathy (NE) often remains elusive owing to our limited understanding of the underlying pathophysiological processes and lack of appropriate biomarkers.

OBJECTIVES

This retrospective observational study describes a case series of term newborns with NE who displayed a recognizable magnetic resonance imaging pattern of immediately postnatal brain abnormalities that rapidly evolved toward cavitation. Our aim is to (1) report this neuroimaging pattern, (2) look for placental determinants, and (3) depict the outcome.

DESIGN/METHODS

This is a unicentric retrospective case series reporting the clinical, radiological, and laboratory findings of NE associated with a distinctive neuroimaging pattern, that is, immediately postnatal extensive corticosubcortical T2 hyperintensities, followed by rapid corticosubcortical cavitation that does not match the neuroimaging picture of intrapartum hypoxic-ischemic encephalopathy (HIE).

RESULTS

Seven term newborns presented bilateral corticosubcortical hyperintensities that were detected on T2 between day of life (DOL) 1-4, which rapidly evolved toward cystic encephalomalacia, that is, between DOL9 and DOL12. All these newborns presented with moderate/severe NE. The outcome was either neonatal death or quadriplegic cerebral palsy and epilepsy. None of the reported patients fulfilled the criteria of a high likelihood of acute intrapartum hypoxic-ischemic or quadriplegic cerebral palsy. All these newborns were exposed to chronic and/or acute placental inflammation and/or hypoxic-ischemic.

CONCLUSIONS

To further define the antepartum causes of NE, early neuroimaging and a placental examination are recommended. Brain T2 hyperintense injuries before DOL4 followed by rapid cavitation before DOL12 might be biomarkers of NE from an antepartum/placental origin.

Placental pathology: Pathways leading to or associated with perinatal brain injury in experimental neurology, special issue: Placental mediated mechanisms of perinatal brain injury

Perinatal brain injury is a multifactorial process. In utero placental physiology plays a major role in neuroprotection and the normal development of the fetal central nervous system. Advances in placental pathology have clarified several specific mechanisms of injury and the histologic lesions most strongly associated with them. This review provides an updated summary of the relevant placental anatomy and physiology, the specific placental pathways leading to brain injury, the revised Amsterdam classification system for placental pathology, and the known associations of specific placental lesions with subtypes of adverse neurologic outcomes.