Intrauterine hypoxia (also known as fetal hypoxia) occurs when the fetus is deprived of an adequate supply of

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

. It may be due to a variety of reasons such as

prolapse In medicine, prolapse is a condition in which organ (anatomy), organs fall down or slip out of place. It is used for organs protruding through the vagina, rectum, or for the misalignment of the valves of the heart. A spinal disc herniation is al ...

or occlusion of the

umbilical cord In Placentalia, placental mammals, the umbilical cord (also called the navel string, birth cord or ''funiculus umbilicalis'') is a conduit between the developing embryo or fetus and the placenta. During prenatal development, the umbilical cord i ...

, placental infarction, maternal diabetes (prepregnancy or

gestational diabetes Gestational diabetes is a condition in which a woman without diabetes develops hyperglycemia, high blood sugar levels during pregnancy. Gestational diabetes generally results in few symptoms. Obesity increases the rate of pre-eclampsia, cesarea ...

) and maternal smoking.

Intrauterine growth restriction Intrauterine growth restriction (IUGR), or fetal growth restriction, is the poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's ...

may cause or be the result of hypoxia. Intrauterine hypoxia can cause cellular damage that occurs within the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

(the brain and spinal cord). This results in an increased mortality rate, including an increased risk of

sudden infant death syndrome Sudden infant death syndrome (SIDS), sometimes known as cot death or crib death, is the sudden unexplained death of a child of less than one year of age. Diagnosis requires that the death remain unexplained even after a thorough autopsy and ...

(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 is a group of Non-communicable disease, non-communicable Neurological disorder, neurological disorders characterized by a tendency for recurrent, unprovoked Seizure, seizures. A seizure is a sudden burst of abnormal electrical activit ...

attention deficit hyperactivity disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by symptoms of inattention, hyperactivity, impulsivity, and emotional dysregulation that are excessive and pervasive, impairing in multiple con ...

eating disorders An eating disorder is a mental disorder defined by abnormal eating behaviors that adversely affect a person's health, physical or mental health, mental health. These behaviors may include eating too much food or too little food. Types of eatin ...

and

cerebral palsy Cerebral palsy (CP) is a group of movement disorders that appear in early childhood. Signs and symptoms vary among people and over time, but include poor coordination, spasticity, stiff muscles, Paresis, weak muscles, and tremors. There may b ...

Presentation

Maternal Consequences

Complications arising from intrauterine hypoxia are some of most common causes of preeclampsia. Preeclampsia is a hypertensive disorder that occurs during the second trimester (after the 20th week of pregnancy) resulting from a poorly perfused placenta. The World Health Organization estimates that preeclampsia and eclampsia are responsible for about 14% of maternal deaths globally (around 50,000 to 75,000 deaths annually). During pregnancy, women with preeclampsia faces serious risk of damage to vital organs such as the kidneys, liver, brain, and the blood system. This hypertensive disorder may also cause damage to the placenta leading to issues such as

premature birth Preterm birth, also known as premature birth, is the birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 weeks, very early preterm birth is betwee ...

s, miscarriages, placental abruption, or even stillbirths. In some cases, preeclampsia can eventually lead to stroke and organ failure. Untreated, preeclampsia can progress and turn into eclampsia which is much more severe with the addition of seizures. Eclampsia seizures could lead to uncontrollable twitching and a loss of consciousness, which could potentially lead to the death of the mother and or the baby.

Cause

Intrauterine hypoxia can be attributed to maternal, placental, or fetal conditions. Kingdom and Kaufmann classifies three categories for the origin of fetal hypoxia: 1) pre-placental (both mother and fetus are hypoxic), 2) utero-placental (mother is normal but placenta and fetus is hypoxic), 3) post-placental (only fetus is hypoxic). Pre-placental hypoxia is most commonly caused by external hypoxic environments (such as high altitude). It can also be caused by maternal respiratory conditions (such as asthma), cardiovascular conditions (such as

heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome caused by an impairment in the heart's ability to Cardiac cycle, fill with and pump blood. Although symptoms vary based on which side of the heart is affected, HF ...

pulmonary hypertension Pulmonary hypertension (PH or PHTN) is a condition of increased blood pressure in the pulmonary artery, arteries of the lungs. Symptoms include dypsnea, shortness of breath, Syncope (medicine), fainting, tiredness, chest pain, pedal edema, swell ...

, and cyanotic heart disease), and hematological conditions (such as

anemia Anemia (also spelt anaemia in British English) is a blood disorder in which the blood has a reduced ability to carry oxygen. This can be due to a lower than normal number of red blood cells, a reduction in the amount of hemoglobin availabl ...

). Conditions such as obesity, nutritional deficiencies, infections, chronic inflammations, and stress can also affect the maternal oxygen supply and fetal uptake. The most preventable cause is maternal smoking.

Cigarette smoking Tobacco smoking is the practice of burning tobacco and ingesting the resulting smoke. The smoke may be inhaled, as is done with cigarettes, or released from the mouth, as is generally done with pipes and cigars. The practice is believed to hav ...

by expectant mothers has been shown to have a wide variety of deleterious effects on the developing fetus. Among the negative effects are

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

induced tissue hypoxia and

placental insufficiency Placental insufficiency or utero-placental insufficiency is the failure of the placenta to deliver sufficient nutrients to the fetus during pregnancy, and is often a result of insufficient blood flow to the placenta. The term is also sometimes us ...

which causes a reduction in blood flow from the

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

to the

placenta The placenta (: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas, and waste exchange between ...

thereby reducing the availability of oxygenated blood to the fetus. Placental insufficiency as a result of smoking has been shown to have a

causal Causality is an influence by which one Event (philosophy), event, process, state, or Object (philosophy), object (''a'' ''cause'') contributes to the production of another event, process, state, or object (an ''effect'') where the cause is at l ...

effect in the development of

pre-eclampsia Pre-eclampsia is a multi-system disorder specific to pregnancy, characterized by the new onset of hypertension, high blood pressure and often a significant amount of proteinuria, protein in the urine or by the new onset of high blood pressure a ...

. 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 in the United Kingdom found that smokers were five times more likely to develop pre-eclampsia.

Nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...

alone has been shown to be a teratogen which affects the

autonomic nervous system The autonomic nervous system (ANS), sometimes called the visceral nervous system and formerly the vegetative nervous system, is a division of the nervous system that operates viscera, internal organs, smooth muscle and glands. The autonomic nervo ...

, 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, thereby reducing the amount of red blood cells available for oxygen

transport Transport (in British English) or transportation (in American English) is the intentional Motion, movement of humans, animals, and cargo, goods from one location to another. Mode of transport, Modes of transport include aviation, air, land tr ...

. Utero-placental hypoxia is associated with abnormal placental implantation, impaired vascular remodeling and vascular diseases. It is also associated with pregnancies complicated by

gestational hypertension Gestational hypertension or pregnancy-induced hypertension (PIH) is the development of new hypertension in a pregnant woman after 20 weeks of gestation without the presence of protein in the urine or other signs of pre-eclampsia. Gestational hype ...

intrauterine growth restriction Intrauterine growth restriction (IUGR), or fetal growth restriction, is the poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's ...

, and

. Post-placental hypoxia is associated with mechanical obstructions of the umbilical cords, reduced uterine artery flow, progressive fetal cardiac failure, and genetic anomalies. The perinatal brain injury occurring as a result of birth asphyxia, manifesting within 48 hours of birth, is a form of hypoxic ischemic encephalopathy.

Diagnosis

Treatment

Treatment of infants with 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. There has long been a debate over whether newborn infants with birth asphyxia should be resuscitated with 100% oxygen or normal air. It has been demonstrated that high concentrations of oxygen lead to generation of oxygen

free radicals In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired electron, unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemical reaction, chemi ...

, which have a role in

reperfusion injury Reperfusion injury, sometimes called ischemia-reperfusion injury (IRI) or reoxygenation injury, is the tissue damage caused when blood supply returns to tissue ('' re-'' + ''perfusion'') after a period of ischemia or lack of oxygen (anoxia or hy ...

after asphyxia. Research by Ola Didrik Saugstad and others led to new international guidelines on newborn resuscitation in 2010, recommending the use of normal air instead of 100% oxygen. Increasing the oxygen concentration to the mother has shown little effect on the fetus as hyperoxygenated blood does not perfuse the placental exchange site well. Underlying etiology of intrauterine hypoxia serves as a potential therapeutic target. If maternal preeclampsia is the underlying cause of fetal growth restriction (FGR) antihypertensive therapy and magnesium sulfate are potential therapies. Antihypertensive treatment is used to reduce blood pressure and prevent pulmonary edema and cerebral hemorrhages. An effective course of antihypertensive treatments should reduce blood pressure to below 160/110 mmHg. Magnesium sulfate acts as a vasodilator, reducing vascular resistance and protect the blood-brain barrier (BBB). The goal of these treatments is to prolong pregnancy and increase fetal survival. Each day gained by treatment in utero increases fetal survival and intact survival by 1%–2% up to 28 weeks gestation.

Prevention

Medical testing and care can be performed in order to prevent intrauterine hypoxia, though can be difficult. These tests don't directly detect hypoxia, but instead detects the general well-being of the baby and ensures that the baby is healthy since hypoxia causes a wide range of responses. These tests can include prenatal testing, such as fetal movement and amniotic fluid levels, Doppler examination, or fetal heart rate. Another risk factor is premature birth in which medical intervention, such as premature birth prevention or C-section delivery, can be used as prevention for intrauterine hypoxia. Studies have shown a connection between tetrahydrobiopterin (BH₄) deficiency and hypoxia-ischemia brain injury, though further studies need to be done. Measuring fetal BH₄ levels can be another way to look out for intrauterine hypoxia. During birth, birth asphyxia can occur in which cardiotocograph can be used to monitor the baby's health during labor.

Epidemiology

In the United States, intrauterine hypoxia and birth asphyxia were listed together as the tenth leading cause of neonatal death.

Society

IH/BA is also a causative 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.

Medicolegal

In the United States the National Practitioner Data Bank 2006 Annual Report obstetrics-related cases accounted for 8.7 percent of all 2006 physician Malpractice Payment Reports and had the highest median payment amounts ($333,334).

References

External links

* * * {{Certain conditions originating in the perinatal period Respiratory diseases Respiratory and cardiovascular disorders specific to the perinatal period