Steroid Injections Can Reduce Preemie Complications

Nurse tending to newborn in incubator
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When a baby is at risk of a premature delivery, the doctor will often give the mother a series of steroid injections to help speed the development of the baby's lungs. Referred to as antenatal steroid therapy, the procedure is surprisingly effective in reducing the risk of potentially life-threatening complications, including respiratory distress syndrome (RDS).

Betamethasone or dexamethasone are the two steroids commonly used in cases of preterm delivery, injected at least 24 hours before and ideally no more than a week in advance of the baby's birth. The therapy is prescribed in a series of two shots delivered 24 hours apart.

How Antenatal Steroids Work

Steroids, more appropriately referred to as corticosteroids, are synthetic forms of natural human hormones used to reduce inflammation. When applied antenatally, the drug is transported to the baby through the mother's bloodstream and aids in maturing the baby's lungs in two key ways:

  • It increases the production of surfactants, a mixture of lipids and proteins produced by the body, which 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.

If the injections are given more than a week before the birth, the effects tend to wane and may potentially reverse the benefits of treatment. Because it is unadvised to undergo multiple courses, it is important to time the injections as closely to the prescribed window as possible.

Possible Side Effects of Steroid Use in Preterm Babies

Most studies have concluded that the use of antenatal steroids causes no long-term harm to the baby. While there had been some suggestions that the practice was linked to adiposity (increased body fat and weight) in children, most of the research had been limited to animal models.

A study published in the June 2017 edition of Pediatric Research contradicted the claim, concluding that 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.

With that being said, one of the more common side effects of antenatal steroid use is low birth weight, typically related to babies who had been exposed to more than one course of corticosteroids.

The bulk of current evidence suggests that babies exposed to multiple doses have a 300 percent greater risk of low body weight and no better or worse outcomes compared to babies exposed to a single course.

In all but a few cases, the low birth weight babies would ultimately "catch up" by the time they were toddlers with no impact to either cognitive or motor development.

Similarly, there is no evidence that antenatal steroids can harm the mother (other than, perhaps, by causing localized pain or swelling at the injection site). The only exception was among mothers who had undergone multiple courses, a handful of whom had reported temporary sleeping problems.

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  • American College of Obstetrics and Gynecologists. ACOG Committee Opinion: Antenatal Corticosteroid Therapy of Fetal Maturation. Obstetrics and Gynecology. 2017; 130(2): e102-e109. DOI: 10.1097/AOG.0000000000002237.

  • Washburn, L.; Nixon, P.; Snively, B. et al. Antenatal Corticosteroids and Cardiometabolic Outcomes in Adolescents Born With Very Low Birth Weight. Pediatric Research. 2017; 82-107. DOI: 10.1038/pr.2017.133.

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