Impact of maternal hypertensive disorders of pregnancy on brain volumes at term-equivalent age in preterm infants: A voxel-based morphometry study

Prenatal inflammation impairs early CD11c-positive microglia induction and delays myelination in neurodevelopmental disorders

Histological chorioamnionitis (HCA) is a form of maternal immune activation (MIA) linked to an increased risk of neurodevelopmental disorders in offspring. Our previous study identified neurodevelopmental impairments in an MIA mouse model mimicking HCA. Thus, this study investigated the role of CD11c+ microglia, key contributors to myelination through IGF-1 production, in this pathology. In the mouse model, the CD11c+ microglial population was significantly lower in the MIA group than in the control group on postnatal day 3 (PN3d). Furthermore, myelination-related protein levels significantly decreased in the MIA group at PN8d. In humans, preterm infants with HCA exhibited higher IL-6 and IL-17A cord-serum levels and lower IGF-1 levels than those without HCA, followed by a higher incidence of delayed myelination on magnetic resonance imaging at the term-equivalent age. In silico analysis revealed that the transient induction of CD11c+ microglia during early development occurred similarly in mice and humans. Notably, a lack of high CD11c+ microglial population has been observed in children with neurodevelopmental disorders. This study reports impaired induction of CD11c+ microglia during postnatal development in a mouse model of MIA associated with delayed myelination. Our findings may inform strategies for improving outcomes in infants with HCA.

Multi-Organ Phenotypes of Offspring Born Following Hypertensive Disorders of Pregnancy: A Systematic Review

BACKGROUND

Hypertensive pregnancies are associated with an increased risk of cardiovascular and neurological diseases in the offspring during later life. However, less is known about the potential impact on multi-organ phenotypes in offspring before disease symptoms occur. The objective of this systematic review was to determine the associations of fetal exposure to maternal hypertensive pregnancy with multi-organ phenotypes across developmental stages.

METHODS AND RESULTS

Ovid MEDLINE, EMBASE, CENTRAL (Cochrane Central Register of Controlled Trials), WoS, Scopus, CINAHL, and ClinicalTrials.gov were systematically searched until February 2024. Records were independently screened by 2 authors. Studies reporting on the structure or function of the heart, blood vessels, brain, liver, and kidneys in offspring of hypertensive pregnancies compared with a normotensive control population were included. Risk of bias was assessed using the Newcastle-Ottawa Scale. Extracted data were presented using harvest plots. Seventy-three studies including 7091 offspring of hypertensive pregnancies and 42 164 controls were identified that met the inclusion criteria. Thirty-two studies were investigations in fetuses, 24 in neonates and infants, 12 in children, 2 in adolescents, and 3 in adults. Offspring of hypertensive pregnancies had structural and functional changes in the heart compared with controls in some studies across developmental stages. Offspring of hypertensive pregnancies also had smaller occipital and parietal vessels, higher aortic intima-media thickness, and lower retinal arteriolar-to-venular ratio. Some conflicting evidence existed for other phenotypical alterations.

CONCLUSIONS

There is still inconsistent evidence of multi-organ structural and functional differences in offspring of hypertensive pregnancies. The evidence base could therefore be further strengthened through well-designed and conducted prospective studies.

REGISTRATION INFORMATION

www.crd.york.ac.uk. Unique Identifier: CRD42023387550.

Hypertensive Disorders of Pregnancy and Risk of Early Brain Abnormalities on Magnetic Resonance Imaging at Term among Infants Born at ≤32 Weeks' Gestational Age

OBJECTIVE

To evaluate the proximal effects of hypertensive disorders of pregnancy (HDP) on a validated measure of brain abnormalities in infants born at ≤32 weeks' gestational age (GA) using magnetic resonance imaging at term-equivalent age.

STUDY DESIGN

In a multisite prospective cohort study, 395 infants born at ≤32 weeks' GA, underwent 3T magnetic resonance imaging scan between 39 and 44 weeks' postmenstrual age. A single neuroradiologist, blinded to clinical history, evaluated the standardized Kidokoro global brain abnormality score as the primary outcome. We classified infants as HDP-exposed by maternal diagnosis of chronic hypertension, gestational hypertension, pre-eclampsia, or eclampsia. Linear regression analysis identified the independent effects of HDP on infant brain abnormalities, adjusting for histologic chorioamnionitis, maternal smoking, antenatal steroids, magnesium sulfate, and infant sex. Mediation analyses quantified the indirect effect of HDP mediated via impaired intrauterine growth and prematurity and remaining direct effects on brain abnormalities.

RESULTS

A total of 170/395 infants (43%) were HDP-exposed. Adjusted multivariable analyses revealed HDP-exposed infants had 27% (95% CI 5%-53%) higher brain abnormality scores than those without HDP exposure (P = .02), primarily driven by increased white matter injury/abnormality scores (P = .01). Mediation analyses showed HDP-induced impaired intrauterine growth significantly (P = .02) contributed to brain abnormality scores (22% of the total effect).

CONCLUSIONS

Maternal hypertension independently increased the risk for early brain injury and/or maturational delays in infants born at ≤32 weeks' GA with an indirect effect of 22% resulting from impaired intrauterine growth. Enhanced prevention/treatment of maternal hypertension may mitigate the risk of infant brain abnormalities and potential neurodevelopmental impairments.

Intrauterine exposure to chorioamnionitis and neuroanatomical alterations at term-equivalent age in preterm infants

PURPOSE

Infants born to mothers with chorioamnionitis (CAM) are at increased risk of developing adverse neurodevelopmental disorders in later life. However, clinical magnetic resonance imaging (MRI) studies examining brain injuries and neuroanatomical alterations attributed to CAM have yielded inconsistent results. We aimed to determine whether exposure to histological CAM in utero leads to brain injuries and alterations in the neuroanatomy of preterm infants using 3.0- Tesla MRI at term-equivalent age.

METHODS

A total of 58 preterm infants born before 34 weeks of gestation at Nagoya University Hospital between 2010 and 2018 were eligible for this study (CAM group, n = 21; non-CAM group, n = 37). Brain injuries and abnormalities were assessed using the Kidokoro Global Brain Abnormality Scoring system. Gray matter, white matter, and subcortical gray matter (thalamus, caudate nucleus, putamen, pallidum, hippocampus, amygdala, and nucleus accumbens) volumes were evaluated using segmentation tools (SPM12 and Infant FreeSurfer).

RESULTS

The Kidokoro scores for each category and severity in the CAM group were comparable to those observed in the non-CAM group. White matter volume was significantly smaller in the CAM group after adjusting for covariates (postmenstrual age at MRI, infant sex, and gestational age) (p = 0.007), whereas gray matter volume was not significantly different. Multiple linear regression analyses revealed significantly smaller volumes in the bilateral pallidums (right, p = 0.045; left, p = 0.038) and nucleus accumbens (right, p = 0.030; left, p = 0.004) after adjusting for covariates.

CONCLUSIONS

Preterm infants born to mothers with histological CAM showed smaller volumes in white matter, pallidum, and nucleus accumbens at term-equivalent age.

Neurodevelopmental Disruptions in Children of Preeclamptic Mothers: Pathophysiological Mechanisms and Consequences

Preeclampsia (PE) is a multisystem disorder characterized by elevated blood pressure in the mother, typically occurring after 20 weeks of gestation and posing risks to both maternal and fetal health. PE causes placental changes that can affect the fetus, particularly neurodevelopment. Its key pathophysiological mechanisms encompass hypoxia, vascular and angiogenic dysregulation, inflammation, neuronal and glial alterations, and disruptions in neuronal signaling. Animal models indicate that PE is correlated with neurodevelopmental alterations and cognitive dysfunctions in offspring and in humans, an association between PE and conditions such as cerebral palsy, autism spectrum disorder, attention deficit hyperactivity disorder, and sexual dimorphism has been observed. Considering the relevance for mothers and children, we conducted a narrative literature review to describe the relationships between the pathophysiological mechanisms behind neurodevelopmental alterations in the offspring of PE mothers, along with their potential consequences. Furthermore, we emphasize aspects pertinent to the prevention/treatment of PE in pregnant mothers and alterations observed in their offspring. The present narrative review offers a current, complete, and exhaustive analysis of (i) the pathophysiological mechanisms that can affect neurodevelopment in the children of PE mothers, (ii) the relationship between PE and neurological alterations in offspring, and (iii) the prevention/treatment of PE.

The Value of Diffusion Kurtosis Imaging in Detecting Delayed Brain Development of Premature Infants

Objective: Preterm infants are at high risk of the adverse neurodevelopmental outcomes. Our aim is to explore the value of diffusion kurtosis imaging (DKI) in diagnosing brain developmental disorders in premature infants.

Materials and Methods: A total of 52 subjects were included in this study, including 26 premature infants as the preterm group, and 26 full-term infants as the control group. Routine MRI and DKI examinations were performed. Mean kurtosis (MK), radial kurtosis (RK), fractional anisotropy (FA), and mean diffusivity (MD) values were measured in the brain regions including posterior limbs of the internal capsule (PLIC), anterior limb of internal capsule (ALIC), parietal white matter (PWM), frontal white matter (FWM), thalamus (TH), caudate nucleus (CN), and genu of the corpus callosum (GCC). The chi-squared test, t-test, Spearman's correlation analysis, and receiver operating characteristic curve were used for data analyses.

Results: In the premature infant group, the MK and RK values of PLIA, ALIC, and PWM were lower than those in the control group (p < 0.05). The FA values of PWM, FWM, and TH were also lower than those of the control group (p < 0.05). The area under curves of MK in PLIC and ALIC, MD in PWM, and FA in FWM were 0.813, 0.802, 0.842, and 0.867 (p < 0.05). In the thalamus and CN, the correlations between MK, RK values, and postmenstrual age (PMA) were higher than those between FA, MD values, and PMA.

Conclusion: Diffusion kurtosis imaging can be used as an effective tool in detecting brain developmental disorders in premature infants.

Hypertensive disorders of pregnancy and alterations in brain metabolites in preterm infants: A multi-voxel proton MR spectroscopy study

BACKGROUND

Infants born to mothers with hypertensive disorders of pregnancy (HDP) have adverse neurodevelopmental consequences in later life. Magnetic resonance spectroscopy (MRS) is used to predict subsequent neurodevelopment in the field of perinatology.

AIM

We aimed to determine whether exposure to HDP in utero leads to alterations in brain metabolites in preterm infants using multi-voxel proton MRS at term-equivalent age.

STUDY DESIGN

Retrospective cohort study.

SUBJECTS

A total of 103 preterm infants born before 34 weeks of gestation at Nagoya University Hospital between 2010 and 2018 were eligible. Twenty-seven infants were born to mothers with HDP (HDP group), and 76 were born to mothers without HDP (non-HDP group).

OUTCOME MEASURES

The peak area ratios of N-acetylaspartate (NAA)/choline (Cho), NAA/creatine (Cr), and Cho/Cr were evaluated at 10 designated regions of interest (bilateral frontal lobes, basal ganglia, thalami, temporal lobes, and occipital lobes).

RESULTS

The peak area ratios of NAA/Cho and NAA/Cr in the bilateral thalami were significantly higher in the HDP group than in the non-HDP group after adjustment for covariates (postmenstrual age at MRS assessment and infant sex). No significant differences were observed in other regions. Preeclampsia, abnormal umbilical artery blood flow, and fetal growth restrictions were significantly associated with increased NAA/Cho and NAA/Cr ratios in the thalami.

CONCLUSIONS

Based on the evidence that NAA/Cho and NAA/Cr ratios constantly increase with postmenstrual age in normal brain development, exposure to maternal HDP in utero may accelerate brain maturation and increase neuronal activity in preterm infants.