Antenatal Corticosteroids for Fetal Lung Development
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How It Works
Betamethasone and dexamethasone cause an immature fetus's lungs to produce a compound called surfactant. A full-term baby's lungs naturally produce surfactant, which lubricates the lining of the air sacs within the lungs. This allows the inner surfaces of the air sacs to slide against one another without sticking during breathing. Premature infants whose lungs have begun producing surfactant are more able to breathe on their own, or with less respiratory treatment, after birth.
Why It Is Used
Betamethasone and dexamethasone are corticosteroids, also called glucocorticoids, that are given before birth (antenatally) to speed up a preterm fetus's lung development. Either is used when a mother is in preterm labor and birth may occur within 7 days. This helps prevent respiratory distress syndrome (RDS) and related complications following premature birth.
Many infants born at 33 to 34 weeks' gestation have sufficient lung maturity to breathe on their own. But considering the low-risk, high-benefit nature of this treatment, corticosteroids are typically used up to 34 weeks of pregnancy.
How Well It Works
Research shows that corticosteroids, when given to the mother during preterm labor, reduce serious problems for the baby who is born preterm.1
Betamethasone or dexamethasone is most effective if delivery occurs at least 24 hours after the first dose of the medicine has been given and less than 7 days after the last dose of the medicine.
Either medicine will benefit a premature newborn by lowering the risk of:
Corticosteroid side effects that might affect the mother include fluid retention and increased blood pressure. But these are short-term side effects and less likely to occur at all during such a short period of treatment. These side effects are more of a concern during long-term treatment for other health problems.
Control of diabetes may be more difficult in pregnant women when corticosteroids are used. Your doctor may recommend a different insulin dose during this time.
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What To Think About
A second course of corticosteroids may be given if the mother is still at risk of preterm birth before 34 weeks and if the first course of this medicine was at least 1 week earlier.2
Last Revised: January 8, 2013
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