Birth Asphyxia

Birth asphyxia occurs when a baby does not 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 birth 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 of 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 pregnancies that are post-term, particularly those that are longer than 42 weeks

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 cause a baby to have a decreased heart rate, decreased blood flow out of the heart and low blood pressure. 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 (GI) tract, lungs and kidneys.

Experts at UCSF Children's Hospital care for infants in the William H. Tooley Intensive Care Nursery.

Reviewed by health care specialists at UCSF Children's Hospital.
Last updated May 8, 2007