Preemies between 28 and 32 weeks are not harmed by a treatment no longer used to help their lungs mature before birth, according to findings of a study in this month's Pediatrics. Even though previous observational studies suggested that repeated courses of steroids in the womb may result in brain damage, this study shows that the babies' brains are virtually unaffected.
"The consensus in recent years has been to no longer give women in preterm labor more than one course of steroids because of possible adverse effects, but it means more babies are born needing ventilation," said Sanjiv Amin, M.D., assistant professor of Pediatrics at the University of Rochester Medical center and author of the study. "These findings may give us back a tool to help give these fragile babies a better chance of survival."
Before concerns arose in 2000 about safety of multiple courses of steroids, many mothers in on-and-off preterm labor received several rounds before delivering. Now, when mothers go into preterm labor, obstetricians will often administer only a single course of steroids to help strengthen the baby's lungs upon birth. But if the birth is successfully held off for more than seven days, the mother does not receive another course of medication and the baby's lungs may not be protected.
This is regrettable, because one of the biggest challenges for babies born preterm is breathing on their own. Many develop respiratory distress syndrome because their lungs have not developed a protective film over their air sacks, called surfactant, which aids in the transfer of oxygen and decreases the work of breathing. Because of that, they may receive medications and supplemental oxygen, which can cause problems of their own. Some infants develop bronchopulmonary dysplasia, a scarring and inflammation of the lungs, from the oxygen treatment. Others can begin to leak air through the lungs and into the body cavity. Any of these complications, especially coupled with an infection, can be life-threatening.
Previous studies showed neurological complications from multiple courses of dexamethasone, a steroid prepared with sulfur. However, clinicians do not commonly use that steroid anymore and have largely switched to sulfur-free steroids, such as betamethasone. This study was based on infants who received betamethasone prior to birth, and they did not show the same adverse effects as previous studies.
"Perhaps these babies didn't react the same way as in other studies because the timing of brain maturation is different. It could also be because these babies received a different kind of steroid that did not contain sulfur," Amin said. "Preliminarily, it looks like we might be able to use multiple courses of steroids, but we need to do more studies to make sure the treatment is safe and effective."
The study, which was performed by analyzing data collected in the University's neonatal intensive care unit at Golisano Children's Hospital at Strong between 1996 and 1998, included 174 babies who were born at 28 to 32 weeks. Their brain functioning was measured by a neurological assessment given within 24 hours of birth called the auditory brainstem evoked response (ABR), a non-invasive test that measures the brain's response to sounds.
"We considered ABR a window into the whole brain," Amin said. "And it doesn't look like the brain is affected in infants who received multiple courses of betamethasone steroids."
There were no significant differences in the brain's responses to the testing between the 50 babies who received one course of steroids and the 29 who received two or more courses, even when controlled for gestational age, birth weight, race and exposure to illegal drugs. There were also no significant differences between the 51 infants who received no steroids and those who did. The only medical difference between those infants who received one course and those who received more was that the ones who received more were less likely to need mechanical ventilation the day they were born.
The study was partially funded by the National Institutes of Health.
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