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Age of viability

The age at which a premature baby can survive outside of the uterus.
The age of viability occurs sometime between 22 and 26 weeks, usually when the weight is greater than 500 grams. The probability of survival is slim at 22-23 weeks, but increases to approximately 85% at 26-28 weeks. Respiratory problems are the most common complications that a preterm infant experiences. Failure to breathe normally may be due to immaturity, anoxia at birth (lack of oxygen), hemorrhage or drug-induced respiratory depression.
Further Reading:

Gabbe, S. G., Niebyl, J. R., & Simpson, J. L. (Eds.) (1991). Obstetrics: Normal and problems pregnancies. New York: Churchill Livingstone.

Rigatto, H., & Brady, J.P (1972). Periodic breathing and apnea in preterm infants II. Hypoxia as a primary event. Pediatrics. 50, 219.

Related Terms:
Fetal stage

Infant mortality

Self-Instructional Resources:
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