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
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
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.
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
Fetal lung maturity testing
amniotic fluid collected through
amniocentesis) is sometimes used to determine whether
antenatal corticosteroid treatment is necessary.
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
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Haas DM (2011). Preterm birth, search date June 2010.
BMJ Clinical Evidence. Available online:
American College of Obstetricians and Gynecologists
(2012). Management of preterm labor. ACOG Practice Bulletin
No. 127. Obstetrics and Gynecology, 119(6):
Primary Medical Reviewer
||Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer
||William Gilbert, MD - Maternal and Fetal Medicine
Current as of
||January 8, 2013