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Prematurity is the condition of being born before a full gestation. The duration of an average human gestation (length of pregnancy) is 40 weeks from conception to "term." Term etymologically means "end" but in this context has become synonymous with parturition or delivery. A premature birth is often referred to as preterm. A premature infant is sometimes informally called a premie.
Infants born more than 2 weeks prior to 40 weeks show physical signs of their prematurity and may develop other problems as well. Common problems in infants with severe to moderate prematurity (26 to 34 weeks) include neonatal jaundice, hypoglycemia, hypocalcemia, respiratory distress syndrome, bronchopulmonary dysplasia, intracranial hemorrhage, retinopathy of prematurity, and rickets.
Infants with moderate to severe prematurity are often transported to neonatal intensive care units. If a pregnant woman begins labor more than a few weeks prematurely, she is often treated with bedrest and tocolytic agents to suppress labor and prolong the pregnancy. If it appears parturition will proceed regardless, she may be transferred to a hospital with a NICU to reduce the transport risk to the baby.
The earliest gestational age at which the infant may survive is referred to as the limit of viability. As NICU care has improved over the last 40 years, the limit of viability has declined to about 25 weeks (400-500 grams). As risk of brain damage and developmental delay is significant at that degree of earliness even if the infant survives, there are ethical controversies over the aggressiveness of the care rendered to such infants. The limit of viability has also become a factor in the abortion debate.
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