The Etiology and Evolution of Fetal Brain Injury

Abstract

The nine months of intrauterine life are a continuum during which a series of situations and events can occur that result in abnormalities of normal brain growth or injury to the developing brain of the fetus. Genetic mutations and hereditary syndromes can predispose the fetus to intrauterine death, mortality in early life, and various degrees and combinations of brain injury and neurological deficits. Structural brain injury occurs due to a number of well defined and some relatively obscure causes. Premature delivery puts the fetus at risk of complications during birth and in the early days of life that can compromise the brain. Such infants have systems that are physiologically too immature to function normally, making them dependent on a range of care entities many of which are known to have risks associated with their use. The end result especially when prematurity is of extreme degree, is a significant incidence of cognitive and motor deficits. Maternal infection is increasingly recognized to precipitate premature labour and produce inflammatory by-products that cross the placenta and increase the vulnerability of the fetus to brain injury. (Gotsch et al, 2007; Kendall & Peebles 2005; Mercer 2004) Various pathologies related to the placenta also compromise the well being of the fetus. Impaired fetal growth secondary to placental insufficiency is associated with a reduction in the number of brain cells formed by the time the infant is born; growth retarded infants are at increased risk of hypoxic stress and hypoxic ischemic brain injury due to failure of placental blood flow, gas exchange and fetal oxygen delivery. Suboptimal nutrition also poses the risk of hypoglycaemic brain injury immediately after birth. Post mature infants are at risk from placental failure, hypoxic ischaemic injury and birth trauma. Infants conceived with in-vitro fertilization are at increased risk of neurological disability, especially cerebral palsy. (Stromberg et al 2002) Stroke is a significant cause of neurodevelopmental morbidity in newborn infants that can result in permanent sequelae and may be underreported. (Ozduman et al 2004) The overall incidence of cerebral palsy has not been reduced significantly in spite of advances in obstetric care, and CP remains a significant cause for motor deficits and cognitive disability that become evident in early life and result in permanent disability.