Premature Delivery
The average length of a normal pregnancy is 38 weeks, but babies are considered at term after 37 weeks of pregnancy. Any pregnancy that results in a delivery before 36 weeks is considered pre-term. A premature delivery can occur at any time between 26 weeks and 36 weeks of pregnancy. A delivery before 26 weeks is usually considered as non-viable, and if the baby is delivered alive, there is a significant risk of long-term neurologic injury. Since the lungs mature between 32 and 34 weeks, any delivery before 32 weeks presents a risk of immature lungs which may then result in hypoxia, or lack of oxygen, to the brain after delivery. Often a baby born before 34 weeks will require some amount of mechanical assistance for ventilation, which can usually be discontinued after a few weeks in the NICU. The risk of brain injury to a premature baby goes down as the age of the baby increases. Thus, a baby born after 34 weeks of gestational age usually has a low risk of brain injury with long-term consequences, and the treatment of a patient who has premature labor is designed to delay labor and delivery, at least until after 32 weeks. Also, when premature labor is diagnosed, the mother is given an injection of steroids which has been shown to significantly decrease the risk of both lung problems and brain injury even if the baby is delivered prior to 34 weeks.
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