Drugs that help premature babies strengthen their lungs can also impair brain development even at low doses, reports a new study in the journal Science Translational Medicine. This study brings new knowledge to the table that could help doctors and parents make more informed decisions on how to treat preemies.
“The American Academy of Pediatrics suggests that low doses of glucocorticoids can continue to be used in premature babies. This study provides new evidence that these drugs, even at low doses, are associated with impaired cerebellar development when given to babies after birth,” said Emily Tam, lead author of the 19 October study and assistant professor at University of California San Francisco School of Medicine.
“Unfortunately, we don’t have good alternative treatments at this time,” Tam continued. “Low blood pressure and breathing difficulties are big problems for Emily Tam talks about how low doses of commonly used steroid drugs put premature babies at risk for impaired brain development.
premature babies, with serious long-term consequences of their own for the baby’s development.”
Emily Tam talks about how low doses of commonly used steroid drugs put premature babies at risk for impaired brain development. | Video © Science/AAAS
Women who go into preterm labor are often given the glucocorticoid betamethasone to speed up the baby’s lung maturation and shorten the period of time spent on breathing tubes. After birth, premature babies may receive other glucocorticoids like hydrocortisone or dexamethasone to help them maintain normal blood pressure, as well as boost lung function. These issues are life-threatening if not treated, and so many parents are faced with the tough decision of whether or not to give their baby these drugs.
The American Academy of Pediatrics (AAP) has shifted their advice over the years on the issue of steroids. Based on research in animals showing that exposure to glucocorticoids can impair development of the cerebellum (a brain region important in balance, motor learning, language, and behavior), the AAP in 2002 recommended that these drugs not be given to babies after birth. But newer guidelines released in 2010 by the group now suggest that steroids can be used because there hasn’t been enough evidence to show that they harm humans.
Seeking a clearer picture of the effects of glucocorticoids on the premature brain, Tam and colleagues studied 172 premature babies in the United States and Canada, and used advanced MRI analysis techniques to determine the volume of each baby’s cerebellum.
“We are very grateful to all the families who have participated in this study, especially considering the amount of stress they go through with a sick newborn child,” Tam said.
Reassuringly, the team did not see any side effects in babies whose mothers received betamethasone in labor. On the other hand, the researchers found that both hydrocortisone and dexamethasone, when given to premature babies after birth, were associated with decreased growth of the cerebellum. This part of the brain was 10% smaller in the premature infants who received the steroids than in normal newborns.
The researchers plan to follow the babies until they reach school age to determine if impaired cerebellum growth affects cognition or is linked to brain and nervous system disorders. Unfortunately, there are currently no alternative treatments to glucocorticoids, so these results point to the need for new therapies for lung issues in premature babies, or ways to block glucocorticoids’ effects on brain development.
Read the abstract, “Preterm Cerebellar Growth Impairment After Postnatal Exposure to Glucocorticoids,” by Emily Tam and colleagues.