Intrauterine hypoxia
Encyclopedia
Intrauterine
hypoxia
(IH, and birth asphyxia
) occur when the fetus is deprived of an adequate supply of oxygen
. IH is used to describe inadequate oxygen availability during the gestation
period, birth asphyxia (also referred to as perinatal asphyxia or Asphyxia neonatorum ) can result from inadequate supply of oxygen immediately prior to, during or just after delivery. There is considerable controversy over the diagnosis of birth asphyxia due to medicolegal reasons. Because of its lack of precision, the term is eschewed in modern obstetrics.
IH may be due to a variety of reasons such as cord prolapse, cord occlusion, placental infarction and maternal smoking. Intrauterine growth restriction (IUGR) may cause or be the result of hypoxia. Birth asphyxia may result due to prolonged labor, breech delivery
in full-term infants; placental abruption
, and maternal sedation in premature infants. Oxygen deprivation is the most common cause of perinatal brain injury.
Intrauterine hypoxia and birth asphyxia can cause hypoxic ischemic encephalopathy which is cellular damage that occurs within the central nervous system
(the brain and spinal cord) from inadequate oxygen. This results in an increased mortality rate, including an increased risk of Sudden infant death syndrome
(SIDS). Oxygen deprivation in the fetus and neonate have been implicated as either a primary or as a contributing risk factor in numerous neurological and neuropsychiatric disorders such as epilepsy
, ADHD, eating disorders and cerebral palsy
. " The problem of perinatal brain injury, in terms of the costs to society and to the affected individuals and their families, is extraordinary." (Yafeng Dong, PhD)
induced tissue hypoxia and placental insufficiency which causes a reduction in blood flow from the uterus
to the placenta
thereby reducing the availability of oxygenated blood to the fetus. Placental insufficiency as a result of smoking has been shown to have a causal effect in the development of pre-eclampsia
. While some previous studies have suggested that carbon monoxide from cigarette smoke may have a protective effect against preeclampsia, a recent study conducted by the Genetics of Pre-Eclampsia Consortium (GOPEC) in the United Kingdom found that smokers were five times more likely to develop pre-eclampsia.
Nicotine
alone has been shown to be a teratogen
which affects the autonomic nervous system
, leading to increased susceptibility to hypoxia-induced brain damage.
Maternal anemia in which smoking has also been implicated is another factor associated with IH/BA. Smoking by expectant mothers causes a decrease in maternal nucleated red blood cells (NRBC), thereby reducing the amount of red blood cells available for oxygen transport.
The perinatal brain injury occurring as a result of birth asphyxia, manifesting with-in 48 hours of birth, is a form of hypoxic ischemic encephalopathy
.
Treatment of infants suffering birth asphyxia by lowering the core body temperature is now known to be an effective therapy to reduce mortality and improve neurological outcome in survivors, and hypothermia therapy for neonatal encephalopathy
begun within 6 hours of birth significantly increases the chance of normal survival in affected infants.
The World Health Organization
(WHO) estimates that globally, between four and nine million newborns suffer birth asphyxia each year. Leading to an estimated 1.2 million deaths and about the same number of infants who develop severe disability. WHO estimates for global neonatal deaths caused by birth asphyxia are 29%.
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
(IH, and birth asphyxia
Asphyxia
Asphyxia or asphyxiation is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally. An example of asphyxia is choking. Asphyxia causes generalized hypoxia, which primarily affects the tissues and organs...
) occur when the fetus is deprived of an adequate supply of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
. IH is used to describe inadequate oxygen availability during the gestation
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
period, birth asphyxia (also referred to as perinatal asphyxia or Asphyxia neonatorum ) can result from inadequate supply of oxygen immediately prior to, during or just after delivery. There is considerable controversy over the diagnosis of birth asphyxia due to medicolegal reasons. Because of its lack of precision, the term is eschewed in modern obstetrics.
IH may be due to a variety of reasons such as cord prolapse, cord occlusion, placental infarction and maternal smoking. Intrauterine growth restriction (IUGR) may cause or be the result of hypoxia. Birth asphyxia may result due to prolonged labor, breech delivery
Breech birth
A breech birth is the birth of a baby from a breech presentation. In the breech presentation the baby enters the birth canal with the buttocks or feet first as opposed to the normal head first presentation....
in full-term infants; placental abruption
Placental abruption
Placental abruption is a complication of pregnancy, wherein the placental lining has separated from the uterus of the mother. It is the most common pathological cause of late pregnancy bleeding. In humans, it refers to the abnormal separation after 20 weeks of gestation and prior to birth...
, and maternal sedation in premature infants. Oxygen deprivation is the most common cause of perinatal brain injury.
Intrauterine hypoxia and birth asphyxia can cause hypoxic ischemic encephalopathy which is cellular damage that occurs within the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
(the brain and spinal cord) from inadequate oxygen. This results in an increased mortality rate, including an increased risk of Sudden infant death syndrome
Sudden infant death syndrome
Sudden infant death syndrome is marked by the sudden death of an infant that is unexpected by medical history, and remains unexplained after a thorough forensic autopsy and a detailed death scene investigation. An infant is at the highest risk for SIDS during sleep, which is why it is sometimes...
(SIDS). Oxygen deprivation in the fetus and neonate have been implicated as either a primary or as a contributing risk factor in numerous neurological and neuropsychiatric disorders such as epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
, ADHD, eating disorders and cerebral palsy
Cerebral palsy
Cerebral palsy is an umbrella term encompassing a group of non-progressive, non-contagious motor conditions that cause physical disability in human development, chiefly in the various areas of body movement....
. " The problem of perinatal brain injury, in terms of the costs to society and to the affected individuals and their families, is extraordinary." (Yafeng Dong, PhD)
Cause
There are various causes for intrauterine hypoxia (IH). The most preventable cause is maternal smoking. Cigarette smoking by expectant mothers has been shown to have a wide variety of deleterious effects on the developing fetus. Among the negative effects are carbon monoxideCarbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
induced tissue hypoxia and placental insufficiency which causes a reduction in blood flow from the uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
to the placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
thereby reducing the availability of oxygenated blood to the fetus. Placental insufficiency as a result of smoking has been shown to have a causal effect in the development of pre-eclampsia
Pre-eclampsia
Pre-eclampsia or preeclampsia is a medical condition in which hypertension arises in pregnancy in association with significant amounts of protein in the urine....
. While some previous studies have suggested that carbon monoxide from cigarette smoke may have a protective effect against preeclampsia, a recent study conducted by the Genetics of Pre-Eclampsia Consortium (GOPEC) in the United Kingdom found that smokers were five times more likely to develop pre-eclampsia.
Nicotine
Nicotine
Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...
alone has been shown to be a teratogen
Teratology
Teratology is the study of abnormalities of physiological development. It is often thought of as the study of human birth defects, but it is much broader than that, taking in other non-birth developmental stages, including puberty; and other non-human life forms, including plants.- Etymology :The...
which affects the autonomic nervous system
Autonomic nervous system
The autonomic nervous system is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The ANS affects heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils,...
, leading to increased susceptibility to hypoxia-induced brain damage.
Maternal anemia in which smoking has also been implicated is another factor associated with IH/BA. Smoking by expectant mothers causes a decrease in maternal nucleated red blood cells (NRBC), thereby reducing the amount of red blood cells available for oxygen transport.
The perinatal brain injury occurring as a result of birth asphyxia, manifesting with-in 48 hours of birth, is a form of hypoxic ischemic encephalopathy
Cerebral hypoxia
Cerebral hypoxia refers to a reduced supply of oxygen to the brain. Cerebral anoxia refers to a complete lack of oxygen to the brain. There are four separate categories of cerebral hypoxia; in order of severity they are; diffuse cerebral hypoxia , focal cerebral ischemia, cerebral infarction, and...
.
Treatment of infants suffering birth asphyxia by lowering the core body temperature is now known to be an effective therapy to reduce mortality and improve neurological outcome in survivors, and hypothermia therapy for neonatal encephalopathy
Hypothermia therapy for neonatal encephalopathy
Brain hypothermia, induced by cooling a baby to around 33°C for three days after birth, is a treatment for birth asphyxia. It has recently been proven to be the only medical intervention which reduces brain damage, and improves an infant's chance of normal survival...
begun within 6 hours of birth significantly increases the chance of normal survival in affected infants.
Epidemiology
In the United States intrauterine hypoxia and birth asphyxia was listed as the tenth leading cause of neonatal death. Sudden infant death syndrome in which fetal hypoxia has been shown to be a key factor is the third leading cause of death.The World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
(WHO) estimates that globally, between four and nine million newborns suffer birth asphyxia each year. Leading to an estimated 1.2 million deaths and about the same number of infants who develop severe disability. WHO estimates for global neonatal deaths caused by birth asphyxia are 29%.
Financial Costs
Intrauterine hypoxia or birth asphyxia IH/BA was the ninth most expensive medical condition treated in U.S. hospitals by average hospital cost and resultant hospital charge. IH/BA is also a causitive factor in cardiac and circulatory birth defects the sixth most expensive condition, as well as premature birth and low birth weight the second most expensive and it is one of the contributing factors to infant respiratory distress syndrome (RDS) also known as hyaline membrane disease, the most expensive medical condition to treat and the number one cause of infant mortality.| Most expensive medical condition treated in U.S. hospitals. 4 out of 10 linked to intrauterine hypoxia/birth asphxia | Cost | Hospital Charge |
| 1. Infant respiratory distress syndrome | $45,542 | $138,224 |
| 2. Premature birth and low birth weight | $44,490 | $119,389 |
| 6. Cardiac and circulatory birth defects | $35,960 | $101,412 |
| 9. Intrauterine hypoxia or birth asphyxia | $27,962 | $74,942 |