Friday, October 21, 2011

Pre-term babies' exposure to steroids associated with impaired brain growth

Premature infants exposed after birth to drugs known as glucocorticoids are at increased risk for having impaired growth of the cerebellum, according to findings from a new UCSF-led study. The cerebellum is a region of the brain associated with balance, motor learning, language and behavior.

The findings challenge the recent policy statement of The American Academy of Pediatrics, which suggests that low doses of glucocorticoids -- a class of steroid hormones used in premature babies to support lung maturation, the normalization of blood pressure and breathing -- can continue to be used in premies. In their 2010 statement, the Academy recommended that high-dose dexamethasone not be given to babies after birth, but stated that the evidence was insufficient to make a recommendation regarding other doses of glucocorticoids.

In the current study, published in the Oct. 19, 2011, issue of Science Translational Medicine, the researchers found that betamethasone given to mothers in premature labor was not associated with adverse affects on the baby's brain growth. However, they found that premature babies given hydrocortisone or dexamethasone in a low-dose range after birth had, on average, 10 percent smaller cerebellar volumes by the time they were full term.

"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, MD, a child neurologist in the Neurological Intensive Care Nursery at the UCSF Benioff Children's Hospital and lead author of the study.

The long-term impacts on cognitive and motor development will need to be assessed through neurological examinations and developmental testing when the children are at school age, she said. However, previous studies have shown that smaller cerebellar volumes in children born prematurely are associated with significant motor and cognitive impairments by teenage years.

Babies born prematurely may be treated with glucocorticoids for a number of reasons. Betamethasone is often given to mothers in preterm labor to accelerate the baby's lung maturation, and either hydrocortisone or dexamethasone may be given to premature newborns after birth to help with maintaining a normal blood pressure or to shorten the period of time they need help with breathing using a breathing tube.

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