Uses of Steroid Injections
Betamethasone or dexamethasone are the two steroids most commonly used in cases of preterm delivery. These medications are injected at least 24 hours before the baby’s birth, but ideally no more than a week in advance. The therapy is now considered routine care for women at risk of preterm delivery between 23 and 34 weeks gestation—and may safely be used up to 37 weeks.
Why It’s Important
The development of this treatment, which began in the early 1970s, has made a huge positive impact on the prognosis for preterm infants. Accelerating the maturation of fetal lungs before delivery has significantly reduced the rate of respiratory distress syndrome (RDS), a primary complication of preterm birth and a leading cause of neonatal death and disability, among other complications.
Preterm Birth Risks
Over 10% of babies born in the United States are born before 37 weeks, which constitutes a significant health risk for these infants. Generally, the earlier a baby is born, the more likely they are to experience adverse outcomes, including death and life-long disability. The use of steroid injections before preterm delivery, among other modern medical interventions, has pushed back the date of fetal viability (generally defined as a 50% survival rate), which is now considered to be 24 weeks—and greatly improved the outlook for preterm babies born after that date. Comprehensive research has confirmed the positive effects and limited drawbacks of this treatment. Antenatal steroid therapy has been proven to reduce the risks and impact of the following complications of being born prematurely:
Bleeding in the brainBreathing problemsIntestinal issuesNeonatal deathNecrotizing enterocolitis (a serious condition of the bowel)
How Antenatal Steroids Work
Steroids, technically called corticosteroids, are synthetic forms of natural human hormones used to reduce inflammation. When given before birth, the drug is transported to the baby through the mother’s bloodstream and aids in quickly maturing the baby’s lungs in two key ways:
The medication increases the production of surfactants, a mixture of lipids and proteins produced by the body that lowers the surface tension within the lungs and makes respiration easier. It reduces fluid in the lungs, further aiding in respiration by increasing lung volume.
Dramatic improvements in a baby’s lungs can be quickly achieved by the administration of these drugs—even just 24 hours of exposure before childbirth can make a big difference in a baby’s prognosis.
Timing
The recommended protocol for this treatment is one course of steroid injections, which includes two shots given 24 hours apart, ideally between 24 hours to one week before delivery. Adverse effects are minimal when one course of medication is used. The use of multiple courses is more controversial and linked to a greater risk of complications. Occasionally, a second course of treatment is given if childbirth is delayed one week after the first set of injections or if there are other indications that the benefits of another round of medication would outweigh the risks of possible side effects. The timing of corticosteroid shots for premature babies is crucial to the success of the treatment. If the injections are given more than a week before the birth, the effects tend to wane and may even reverse the benefits of treatment. Because multiple courses are discouraged due to potential complications, doctors aim to time the injections as closely to the prescribed window as possible.
Possible Side Effects
Comprehensive research has concluded that the use of antenatal steroids has substantial benefits and causes no long-term harm to the baby or mother, particularly when only one set of injections are used. Additionally, even with possible side effects, the life-saving benefits of multiple courses of this treatment must be weighed in relation to any potential risks.
Small Size
Some older research indicated that fetuses exposed to repeated courses of steroids in utero were more likely to show decreased weight, length, and head circumference at birth, compared to fetuses who received a placebo. However, a 2015 study on the efficacy and safety of repeated doses of corticosteroids for improving neonatal health outcomes showed clear benefits and limited drawbacks. While infants receiving treatment were more likely to have a smaller size at birth, no long-term harm was found. However, more research is needed to fully investigate if multiple doses have any lasting impact on height.
Adiposity
A variety of other possible side effects have been investigated, but most concerns have not been supported by scientific evidence. For example, while there had been some suggestions that steroid injections were linked to adiposity (increased body fat and weight) in children, most of the research showing this connection has been limited to animal models. In fact, a study published in the June 2017 edition of Pediatric Research contradicted the claim that the treatment is linked to adiposity. Among 186 14-year-olds who had been born prematurely (some of whom had been exposed to antenatal steroids and others who hadn’t), there was no statistical difference in the rate of adiposity between either group.
Impact on Mothers
Research has not demonstrated evidence that antenatal steroids cause harm to the mother, either, other than causing localized pain or swelling at the injection site. The exception is among mothers who have undergone multiple courses of steroids, some of whom report temporary sleeping problems. However, researchers point out that many mothers of preterm infants also experience issues with sleep.
The Bottom Line
“All women in preterm labor who are between 26 and 34 weeks pregnant in hospitals with access to newborn care should be getting corticosteroids. They’re one of the most effective, safe, and inexpensive treatments for reducing newborn deaths and disability,” says Dr. Marleen Temmerman, director of the department of reproductive health and research at the World Health Organization (WHO).
A Word From Verywell
More than one in 10 babies around the world are born too early, adding up to some 15 million births each year. Preterm birth is the biggest cause of death among newborn babies, and complications of prematurity kill around one million children annually. Ultimately, antenatal steroid therapy provides the best protection against the complications of preterm birth.
