Current paradigms and new perspectives on fetal hypoxia: implications for fetal brain development in late gestation

Abstract

The availability of oxygen to the fetus is limited by the route taken by oxygen from the atmosphere to fetal tissues, aided or diminished by pregnancy-associated changes in maternal physiology and, ultimately, a function of atmospheric pressure and composition of the mother’s inspired gas. Much of our understanding of the fetal physiological response to hypoxia comes from experiments designed to elucidate the cardiovascular and endocrine responses to transient hypoxia. Complementing this work is equally impactful research into the origins of intrauterine growth restriction in which animal models designed to restrict the transfer of oxygen from the maternal to the fetal circulation were used. A common assumption has been that outcomes measured after a period of hypoxia are related to cellular deprivation of oxygen and reoxygenation: an assumption based on a focus on what we can see “under the streetlights.” Recent studies demonstrate that availability of oxygen may not tell the whole story. Transient hypoxia in the fetal sheep stimulates transcriptomics responses that mirror inflammation. This response is accompanied by the appearance of bacteria in the fetal brain and other tissues, likely resulting from a hypoxia-stimulated release of bacteria from the placenta. The appearance of bacteria in the fetus after transient hypoxia complements the recent discovery of bacterial DNA in the normal human placenta and in the tissues of fetal sheep. An understanding of the mechanism of the physiological, cellular, and molecular responses to hypoxia requires an appreciation of stimuli other than cellular oxygen deprivation: stimuli that we would have never known about without looking “between the streetlights,” illuminating direct responses to the manipulated variables.

Fetal Growth Restriction and Subsequent Low Grade Fetal Inflammatory Response Are Associated with Early-Onset Neonatal Sepsis in the Context of Early Preterm Sterile Intrauterine Environment

“…It is plausible that the intensity of FIR is less potent for the subsequent penetration into the adjacent tissues and cavity (i.e., amnion and amniotic cavity) in sterile inflammation than in microbially induced inflammation. However, it should be noted that transient hypoxia in the fetal sheep stimulates transcriptomics responses that mirror inflammation, and this response may be accompanied by the appearance of bacteria in the fetal compartment of placenta, likely resulting from a hypoxia-stimulated release of bacteria from the maternal compartment to the fetal compartment of placenta due to the increased leakiness of placenta [ 60 ]. Therefore, we should recognize that an understanding of the mechanism of the physiological, cellular, and molecular responses to hypoxia may require an appreciation of stimuli other than cellular oxygen deprivation in spite of quite a small stimulus (i.e., very small numbers of bacteria not detected by culture method of AF and placenta) [ 60 ].…”

Promoting sound development of preterm infants in the name of developmental neuroscience: Beyond advanced life support and neuroprotection

“…15,16 Within the uterus, oxygen and other energy substrates are provided via the placenta. 17 However, human foetuses are allowed to use only limited amount of oxygen because the partial oxygen tension of the foetal arterial blood typically remains at less than 25 mmHg. 18 It would be relevant that foetal cerebral function is attenuated to match extremely low oxygen supply, the level of which is even lower compared with that of newborn infants.…”

Взаимосвязь Кариозных Поражений У Детей До 3 Лет Со Степенью Гипоксии Плода

“…К сегодняшнему дню проведен ряд исследований, посвященных изучению отрицательного действий осложнений в ходе беременности женщины на формирование и развитие зубо-челюстной системы (ЗЧС) плода. Большая часть работ посвящена развитию кариесогенных поражений, так как они являются наиболее распространёнными среди детского населения [3,4,5].…”