The health of an infant is assessed in various ways, including observation and measurement of important blood components. Measurement of oxygen saturation provides information about a baby's respiratory, heart and circulatory health. The American Academy of Pediatrics recommends oxygen saturation measurement as part of a newborn's health assessment. This is particularly important for a baby born prematurely or who experiences breathing difficulty, and to screen for possible heart malformations. A healthy, full-term infant normally has an oxygen saturation of 95 to 100 percent, a level that is usually achieved within 10 to 15 minutes after birth.
Oxygen Saturation and Its Measurement
Hemoglobin is the component of red blood cells that binds oxygen and transports it to body tissues. Oxygen saturation reflects the percentage of hemoglobin in the blood that is saturated with oxygen -- meaning it's carrying the maximum amount of oxygen it is capable of holding. Oxygen saturation is commonly measured by pulse oximetry. This instrument uses an infrared and red light source to detect oxygen saturation without collecting a blood sample. A pulse oximeter is typically wrapped around an infant’s foot or hand to obtain a measurement.
At birth, a baby transitions from receiving oxygen from the mother's blood to acquiring oxygen by breathing. In a healthy, full-term baby, the oxygen saturation climbs steadily in the first 10 to 15 minutes after birth until reaching a normal level of 95 to 100 percent. However, there is individual variation and some otherwise healthy babies might take a bit longer to achieve a normal oxygen saturation level. A full-term baby who has a low birth weight or experiences breathing difficulties and requires supplemental oxygen may have a slightly lower oxygen saturation level after birth.
Babies born prematurely commonly have lower oxygen saturation levels initially because their lungs are not fully developed. The more premature a baby is, the more likely the oxygen saturation level will be low. Although recommendations vary and the degree of prematurity is an important consideration, the target oxygen saturation level for premature babies is usually 85 to 95 percent. Premature babies often require supplemental oxygen to maintain an appropriate oxygen saturation level. The healthcare team monitors an infant's oxygen saturation and adjusts the supplemental oxygen to maintain an appropriate level.
A lower than normal oxygen saturation level detected by pulse oximetry usually indicates an oxygen deficiency, or hypoxemia. This condition puts the infant at risk for brain and other organ damage if not corrected quickly. Hypoxemia may not be readily apparent if the oxygen saturation is not measured. For example, a bluish discoloration around the lips is a physical sign of low blood oxygen. However, this sign often does not develop until the oxygen saturation drops to 75 percent or less in a full-term infant.
Beyond the Newborn Period
Assessment of an infant's oxygen saturation level is important in the initial newborn period, as previously described. The normal oxygen saturation level for a healthy infant in the first year of life and beyond remains at 95 to 100 percent. Measurement of oxygen saturation is not typically part of well-baby care outside of the initial period after birth. However, pulse oximetry testing or ongoing monitoring may be recommended for at-risk infants, such as those who have a condition called apnea of prematurity. This condition affects some premature babies during their first year of life, and involves brief pauses in breathing with an accompanying drop in oxygen saturation and heart rate.
Talk with your doctor if you have concerns about your baby's oxygen saturation level, particularly if your infant was born prematurely or has health problems that might affect healthy breathing or circulation. Seek emergency medical care if your baby experiences breathing difficulty, or develops bluish or purplish discoloration of the skin.
Reviewed and revised by: Tina M. St. John, M.D.