Birth Asphyxia

Birth asphyxia occurs when a baby doesn't receive enough oxygen before, during or just after birth. There are many reasons that birth asphyxia may occur.

Some of the causes of decreased oxygen before or during the birth process may include:

  • Inadequate oxygen levels in the mother's blood due to heart or respiratory problems or lowered respirations caused by anesthesia
  • Low blood pressure in the mother
  • Inadequate relaxation of the uterus during labor that prevents oxygen circulation to the placenta
  • Early separation of the placenta from the uterus, called placental abruption
  • Compression of the umbilical cord that decreases blood flow
  • Poor placenta function that may occur with high blood pressure or in post-term pregnancies, particularly those past 42 weeks
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Factors that may lower oxygen in the baby after birth include:

  • Severe anemia, or a low blood cell count, that limits the oxygen-carrying ability of the blood
  • Low blood pressure or shock
  • Respiratory problems that limit oxygen intake
  • Heart or lung disease

Low oxygen levels may decrease a baby's heart rate, blood pressure and blood flow out of the heart. This may limit the blood flow to organs and tissues, leading to improper cell function or damage. Organs typically affected by lowered oxygen include the brain, heart and blood vessels, gastrointestinal tract, lungs and kidneys.

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Each baby may experience symptoms of birth asphyxia differently. However, the following are the most common symptoms.

Before delivery, symptoms may include:

  • Abnormal heart rate or rhythm
  • An increased acid level in a baby's blood

At birth, symptoms may include:

  • Bluish or pale skin color
  • Low heart rate
  • Weak muscle tone and reflexes
  • Weak cry
  • Gasping or weak breathing
  • Meconium — the first stool passed by the baby — in the amniotic fluid, which can block small airways and interfere with breathing

The following test are used to diagnose birth asphyxia:

  • Severe acid levels — pH less than 7.00 — in the arterial blood of the umbilical cord.
  • Apgar score of zero to three for longer than five minutes. The Apgar test is used just after birth to evaluate a newborn's color, heartbeat, reflexes, muscle tone and respiration.
  • Neurological problems, such as seizures, coma and poor muscle tone.
  • Respiratory distress, low blood pressure, or other signs of low blood flow to the kidneys or intestines.

Problems with a baby's circulatory, digestive and respiratory systems may also suggest that a baby has birth asphyxia.

Birth asphyxia is a complex condition that can be difficult to predict or prevent. Prompt treatment is important to minimize the damaging effects of decreased oxygen to the baby.

Specific treatment for birth asphyxia is based on:

  • The baby's age, overall health and medical history
  • Severity of the baby's condition
  • The baby's tolerance for specific medications, procedures or therapies
  • Expectations for the course of the condition

Treatment may include:

  • Giving the mother extra oxygen before delivery
  • Emergency delivery or Caesarean section
  • Assisted ventilation and medications to support the baby's breathing and blood pressure
  • Extracorporeal membrane oxygenation (ECMO)

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Reviewed by health care specialists at UCSF Benioff Children's Hospital.

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