Birth asphyxia is a serious medical condition in which a newborn baby fails to receive enough oxygen during or immediately after delivery. To assess for birth asphyxia, medical professionals evaluate the Apgar score, which measures a baby's color, heart rate, reflexes, muscle tone, and breathing. In addition, a doctor may look for signs of hypothermia, low heart rate, and difficulty breathing. Blood tests may also be conducted to look for abnormal levels of certain proteins, enzymes, and gases in the baby's bloodstream. Ultimately, a doctor's diagnosis of birth asphyxia will be based on the baby's symptoms and the results of any tests performed.