When doctors prescribe steroids for lung development, they usually prescribe either betamethatsone or dexamethasone. The two drugs are similar, and have similar results and side effects. To be most effective, steroids should be given at least 24 hours before the birth of the baby, and preferably no more than 1 week before the baby is born.
Giving a mother steroids helps the baby's lung development in several ways:
- Increased surfactant production: Steroids increase the amount of surfactant that a premature baby's lungs produce. Surfactant helps the lungs to stay open, but premature babies often do not produce enough.
- Less fluid in the lungs: When the lungs are filled with fluid, they don't work as well. Steroids can help babies to clear fluid out of their lungs more effectively.
- Larger lung volumes: Babies exposed to steroids around the time of delivery have more lung tissue. Babies with larger lung volumes are able to oxygenate their blood more easily.
- Better response to surfactant therapy: Premature babies are often given one or more doses of artificial surfactant to help their lungs stay open. Babies whose moms got steroids respond better to surfactant therapy.
Almost all doctors agree that at least one course of steroids should be given to a mother who is at high risk for premature labor. There is some research that shows that the effects of the steroids diminish after one week, so a repeat course of steroids may be given if the baby is not born within a week.
Morgan, Maria PhD, Goldenberg, Robert MD and Schulkin, Jay PhD. “Obstetrician-Gynecologists’ Screening and Management of Preterm Birth.” Obstetrics and Gynecology July 2008; 112, 35-41.
Bonanno, Clarissa MD, Fuchs, Karin MD, Wapner, Ronald J. MD. "Single Versus Repeat Courses of Antenatal Steroids to Improve Neonatal Outcomes: Risks and Benefits. Obstetrical and Gynecological Survey April 2007; 62, 261-271.