Determinants of placental insufficiency in fetal growth restriction

Perinatal compromise affects development, form, and function of the hippocampus part two; preclinical studies

The hippocampus is a vital brain structure deep in the medial temporal lobe that mediates a range of functions encompassing emotional regulation, learning, memory, and cognition. Hippocampal development is exquisitely sensitive to perturbations and adverse conditions during pregnancy and at birth, including preterm birth, fetal growth restriction (FGR), acute hypoxic-ischaemic encephalopathy (HIE), and intrauterine inflammation. Disruptions to hippocampal development due to these conditions can have long-lasting functional impacts. Here, we discuss a range of preclinical models of prematurity and FGR and conditions that induce hypoxia and inflammation, which have been critical in elucidating the underlying mechanisms and cellular and subcellular structures implicated in hippocampal dysfunction. Finally, we discuss potential therapeutic targets to reduce the burden of these perinatal insults on the developing hippocampus. IMPACT: The review explores the preclinical literature examining the association between pregnancy and birth complications, and hippocampal form and function. The developmental processes and cellular mechanisms that are disrupted within the hippocampus following perinatal compromise are described, and potential therapeutic targets are discussed.

Neuroprotective effects of maternal melatonin administration in early-onset placental insufficiency and fetal growth restriction

BACKGROUND

Early-onset fetal growth restriction (FGR) is associated with adverse outcomes. We hypothesised that maternal melatonin administration will improve fetal brain structure in FGR.

METHODS

Surgery was performed on twin-bearing ewes at 88 days (0.6 gestation), and FGR induced in one twin via single umbilical artery ligation. Melatonin was administered intravenously (6 mg/day) to a group of ewes commencing on day of surgery until 127 days (0.85 gestation), when the ewe/fetuses were euthanized, and fetal brains collected.

RESULTS

Study groups were control (n = 5), FGR (n = 5), control+melatonin (control+MLT; n = 6) and FGR+melatonin (FGR + MLT; n = 6). Melatonin administration did not significantly alter fetal body or brain weights. Myelin (CNPase+) fibre density was reduced in FGR vs. control animals in most brain regions examined (p < 0.05) and melatonin treatment restored CNPase fibre density. Similar but less pronounced effect was seen with mature myelin (MBP+) staining. Significant differences in activated microglia (Iba-1) activity were seen between lamb groups (MLT mitigated FGR effect) in periventricular white matter, subventricular zone and external capsule (p < 0.05). Similar effects were seen in astrogliosis (GFAP) in intragyral white matter and cortex.

CONCLUSIONS

Maternal melatonin administration in early onset FGR led to improved myelination of white matter brain regions, possibly mediated by decreased inflammation.

IMPACT

Maternal melatonin administration might lead to neuroprotection in the growth-restricted fetus, possibly via dampening neuroinflammation and enhancing myelination. This preclinical study adds to the body of work on this topic, and informs clinical translation. Neuroprotection likely to improve long-term outcomes of this vulnerable infant group.

Resolvin D1 level during different trimesters of pregnancy for predicting the risk of fetal growth retardation in elderly pregnancy

Resolvin D1 (RvD1) is potentially associated with fetal growth retardation (FGR) through alleviating maternal inflammation and its linkage with several pregnancy complications. Thus, this study detected RvD1 levels at different trimesters of pregnancy, aiming to investigate its role in predicting FGR risk of elderly pregnant women. This prospective, observational cohort study enrolled 165 elderly pregnant women aged ≥35 years. Serum RvD1 was detected at 10-13 weeks (early pregnancy), 20-23 weeks (middle pregnancy), and 30-33 weeks (late pregnancy) of gestational week by enzyme-linked immunosorbent assay. RvD1 was varied among different trimesters of pregnancy in elderly pregnant women (p < 0.001). FGR occurred in 25 (15.2%) women in this study. RvD1 at early (p = 0.009), middle (p = 0.002), and late (p = 0.003) pregnancy was decreased in women with FGR versus those without. By multivariate analysis, RvD1 at middle pregnancy (odds ratio (OR): 0.477, p < 0.001), pre-pregnancy body mass index (OR: 0.763, p = 0.025), and gestational diabetes mellitus (yes versus no) (OR: 0.071, p = 0.031) were independently correlated with declined FGR risk. While age (OR: 1.382, p = 0.009) was independently associated with elevated risk of FGR. Furthermore, the combination of these independent factors as a predictive model exhibited a good potential for assessing FGR risk (area under the curve: 0.802, 95% confidence interval: 0.711-0.894). In conclusion, RvD1 at different trimesters of pregnancy is negatively linked with the risk of FGR, whose level at middle pregnancy serves as an independent factor for FGR risk in elderly pregnant women.

Does fetal growth restriction induce neuropathology within the developing brainstem?

Fetal growth restriction (FGR) is a complex obstetric issue describing a fetus that does not reach its genetic growth potential. The primary cause of FGR is placental dysfunction resulting in chronic fetal hypoxaemia, which in turn causes altered neurological, cardiovascular and respiratory development, some of which may be pathophysiological, particularly for neonatal life. The brainstem is the critical site of cardiovascular, respiratory and autonomic control, but there is little information describing how chronic hypoxaemia and the resulting FGR may affect brainstem neurodevelopment. This review provides an overview of the brainstem-specific consequences of acute and chronic hypoxia, and what is known in FGR. In addition, we discuss how brainstem structural alterations may impair functional control of the cardiovascular and respiratory systems. Finally, we highlight the clinical and translational findings of the potential roles of the brainstem in maintaining cardiorespiratory adaptation in the transition from fetal to neonatal life under normal conditions and in response to the pathological environment that arises during development in growth-restricted infants. This review emphasises the crucial role that the brainstem plays in mediating cardiovascular and respiratory responses during fetal and neonatal life. We assess whether chronic fetal hypoxaemia might alter structure and function of the brainstem, but this also serves to highlight knowledge gaps regarding FGR and brainstem development.