Antenatal Corticosteroids for Fetal Lung Development

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Antenatal Corticosteroids for Fetal Lung Development


Generic NameBrand Name
betamethasoneCelestone Soluspan

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.

If delivery does not occur within 7 days of treatment, the injections should not be repeated.

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 labour and birth may occur in 24 to 48 hours. 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

There is strong evidence that a single course of corticosteroid medicine given to the mother during premature labour improves the outcome for the infant born between 24 and 34 weeks' gestation.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:

Side Effects

Corticosteroid side effects that might affect the mother can 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

Fetal lung maturity testing (using amniotic fluid collected through amniocentesis) is sometimes used to determine whether antenatal corticosteroid treatment is necessary.

Repeat courses of corticosteroids given before birth are not recommended.2 They may cause long-term effects on the growing child.3

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  1. Haas DM (2010). Preterm birth, search date June 2009. Online version of BMJ Clinical Evidence:
  2. American Academy of Pediatrics and American College of Obstetricians and Gynecologists (2002). Obstetric and medical complications. In Guidelines for Perinatal Care, 5th ed., pp. 163–185. Washington, DC: American Academy of Pediatrics, American College of Obstetricians and Gynecologists.
  3. French NP, et al. (2004). Repeated antenatal corticosteroids: Effects on cerebral palsy and childhood behavior. American Journal of Obstetrics and Gynecology, 190(3): 588–595.


By Healthwise Staff
Primary Medical Reviewer Sarah Marshall, MD - Family Medicine
Primary Medical Reviewer Brian D. O'Brien, MD - Internal Medicine
Specialist Medical Reviewer William Gilbert, MD - Maternal and Fetal Medicine
Last Revised March 21, 2011

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