Fetal Oxygen Deficiency
Fetal/Infant Oxygen Deficiency
When a fetus does not receive enough oxygen in the uterus while growing, the condition is called intrauterine hypoxia. At the time just before or during labor and delivery, oxygen deprivation to the fetus is called fetal hypoxia or intrapartum hypoxia. All three terms refer to the condition in which the baby’s tissues receive insufficient oxygen, leading to possibly severe complications, including hypoxic brain injuries. Neonatal asphyxia is used to describe a baby just after birth who does not start breathing or whose breathing does not provide enough oxygen to the body. If the brain is deprived of a significant amount of oxygen at any time during gestation or after birth, permanent brain damage (intraventricular hemorrhage, periventricular leukomalacia, etc.) and/or other complications can occur.
Before birth, fetal hypoxia can be suspected if there are signs of fetal distress. During the labor and delivery process an expecting mother will have external and possibly internal monitors attached to her and/or her baby to monitor her contractions (strength and frequency) as well as her baby’s heart rate. The information from these monitors are reported on a fetal monitor strip that can be used by the obstetrician, nurse mid-wife or obstetrical nurses to see how the baby is responding to each contraction and to labor in general. A low fetal heart rate (bradycardia) or unusual decelerations in the baby’s heart rate (late decelerations) may be an indication of fetal distress. In addition, an unusual pattern in the variability of the fetal heart rate may be an indication of brain injury or impending injury to the baby’s brain or central nervous system. If there is evidence of fetal distress and labor is sufficiently progressed, the physician or nurse mid-wife may take a pH sample from the baby’s head to see if oxygen deprivation is occurring.
A baby deprived of oxygen before birth may have difficulty breathing after birth, have too much acid in the bodily fluids, present with brain damage or disorders, or have damaged organs. If the oxygen deprivation occurred throughout the delivery process, the baby may be blue at birth, have no breath sounds, no cry, poor muscle tone or a low heart rate. The baby’s APGAR score may be low and arterial blood gas testing may show a low pH (ie: <7.1) or an elevated Base Excess. Blood sampling from the umbilical cord may be taken to document the baby’s pH and Base Excess at the time of birth. A low pH could mean that the baby was suffering from a metabolic acidosis (low oxygen) as a result of the negative effects of labor.
After birth, a baby (more commonly premature babies) may develop Respiratory Distress Syndrome (RDS). Immediately after birth the baby may be pink, with a good cry, good muscle tone and a normal heart rate. However, within minutes of birth the baby may develop RDS with evidence of grunting, gasping or labored respirations. In premature infants this can occur due to the fact that the fetal lungs have not yet matured. If this occurs, the baby may need supplemental oxygen by mask or may need to be intubated with an endotracheal tube for mechanical ventilation to help the baby breath. Restoration of oxygen delivery is referred to as “resuscitation” of the baby. If resuscitation does not occur, the baby can develop respiratory acidosis evidenced by high levels of CO2 in the baby’s blood. This respiratory acidosis increases the risk that the baby may develop a brain bleed also know as an intraventricular hemorrhage (IVH). An IVH can lead to associated problems such as Cerebral Palsy. If the resuscitation does not provide enough oxygen to the baby, the baby can also develop a metabolic acidosis evidenced by low pH levels in the baby’s blood. Low levels of oxygen can cause anoxic or hypoxic injuries to the baby’s brain leading to periventricular leukomalacia (PVL) and Cerebral Palsy (CP).
Whether evidence of oxygen deprivation occurs in-utero or after birth, it requires timely intervention and resuscitation procedures to ensure the baby regains adequate oxygen supply to prevent hypoxia, brain damage, or death.
Some gestational period risk factors of fetal hypoxia include:
- Fetus that is large for the gestational period/ high birth-weight babies (macrosomic)
- Uterus contains too much amniotic fluid
- Maternal pelvis is too small for delivery (cephalopelvic disproportion)
- Meconium excretion
- Multiple fetuses (twins, triplets, etc)
- Pregnancy problems – placental abruption, placental previa, uterine rupture, excessive bleeding
- Complications from maternal-fetal Rh factor incompatibility
Infants are at a greater risk for asphyxia during labor and delivery when the mother is under the influence of any drug, especially anesthetics or sedatives, because until the time of birth, the mother shares with the fetus any substances that are in her blood stream. For example, narcotic pain medications administered to a woman during labor may have a respiratory affect on the baby at birth. Thus, medical care providers need to be aware that such medication can cause respiratory depression in the baby and lack of oxygen intake if not corrected.
Infants born prematurely may not have a fully developed respiratory system that can provide their bodies with sufficient oxygen. Thus, if premature delivery is imminent, medical care providers need to be aware of the need to give steroids (ie: Betamethasone) for fetal lung maturity. In addition, medical personnel need to be aware of the possible need for surfactant in premature infants.
A labor and delivery that is lengthy or problematic may put a fetus at risk for conditions such as a prolapsed or compromised umbilical cord, which deprive the fetus of an adequate oxygen supply. Protracted labors can also use up a baby’s oxygen stores leaving the baby more susceptible to hypoxia in the final stage of labor.
Deliveries where obstetrical instruments, such as vacuum extractor or forceps, are used have a higher risk of injury to the infant and can lead to conditions that restrict oxygen flow to the brain and other organs. Post-term fetuses are more prone to having passed meconium before birth, and are at risk of aspirating the sticky substance that can block the airways. Infants can also develop pneumonia after coming into contact with the Strep-B organism that some women carry in the birth canal. Any other condition that causes the baby to be born with “severe respiratory distress” can result in hypoxia if respiration is not restored quickly enough.
Because natural labor and delivery help a fetus to expel the fluid that has been in the lungs throughout gestation, cesarean delivered babies can have difficulty in adapting to respiration outside of the womb.
Oxygen deficiency can lead to hypoxia – where the body tissues are compromised due to lack of oxygen. All of the body’s organs are susceptible to damage from inadequate oxygen supply but when the brain sustains damage (Hypoxic Ischemic Encephalopathy also known as HIE), serious consequences can ensue. Damage from oxygen deficiency can lead to palsies, mental retardation, nerve damage, heart defects, bleeding disorders, coma and even death. It is documented that 23% of deaths in newborns are caused by asphyxia or oxygen deprivation.
Many causes of prenatal oxygen deficiency are nearly impossible to detect, and available treatments for certain detectable causes have not been proven successful. During gestation, if there are any organ abnormalities that show up on an ultrasound or sonogram, additional tests can be done to investigate the fetal heart rate and the overall health of the baby. Women with a family history of birth defects, who are diabetic, or who have been exposed to toxins (including drugs and medications) may be recommended to be tested for the probability of their fetus having certain chromosomal or genetic defects. Maternal illness and disease during pregnancy that is appropriately treated can reduce the danger of adverse effects on the growing fetus. Adequate prenatal care is instrumental in reducing the risk of complications in the health of both mother and child.
Up to 20% of infants born with severe cerebral hypoxia do not survive and between 20-25% end up with a disability. For infants born with severe hypoxic ischemic encephalopathy (HIE), new treatments involving cooling therapy or hypothermia of the head or body have been successful in reducing permanent neurological damage and preventing death from the lack of oxygen to the brain in a number of patients. Diagnosis and treatment of underlying causes of oxygen deprivation are instrumental in preventing further damage. After birth, a thorough physical examination and close monitoring in the first few days of life can reveal any problems that require immediate treatment to prevent severe complications. Correct education of parents regarding the warning signs of hypoxia, such as cyanosis, and an accurate description of symptoms as well as a detailed family medical history and record of prenatal care can lead to proper diagnosis of the cause of hypoxia in an infant.
If your baby has been diagnosed with Cerebral Palsy, Hypoxic Ischemic Encephalopathy, Periventricular Leukomalacia or Intraventricular Hemorrhage, you should gather your medical records as well as the medical records of your baby and have them reviewed by an attorney with experience handling medical malpractice cases involving hypoxic injuries or oxygen deprivation.