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Jan. 30, 2007
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Brain bleeding common in newborns, UNC study finds
CHAPEL HILL – A brain development study in newborns revealed intracranial hemorrhages or bleeding in and around the brain, affects 26 percent of babies born vaginally, according to researchers from the University of North Carolina at Chapel Hill.
“This was a very unexpected finding,” said Dr. John H. Gilmore, a professor of psychiatry in the UNC School of Medicine and senior study author. “Intracranial hemorrhage has generally been considered unusual in full-term newborns.”
Most of these hemorrhages, detected by magnetic resonance imaging (MRI), were fairly small and probably resolved quickly, Gilmore said. Neither the size of the baby or the baby’s head, the length of the labor, nor the use of vacuum or forceps to assist the delivery caused the bleeds. “The bleeds are probably caused by pressure on the skull during delivery,” he said.
These findings suggest intracranial hemorrhage is a fairly common consequence of a normal vaginal delivery, the authors said. “I would say that bleeds during vaginal birth are very common and have been happening for a very long time,” Gilmore said. “This not something prospective mothers need to be concerned about.”
The results appear in the February issue of the journal, Radiology. Funding was provided by the National Institute of Mental Health and the UNC School of Medicine.
Discovering brain hemorrhages in newborns was unintended -- Gilmore and his colleagues were investigating the early brain development of babies born to mothers with schizophrenia and babies diagnosed with a condition called fetal isolated mild ventriculomegaly, or MVM. These two groups of babies were considered to be at high risk for developing psychiatric or neurodevelopmental disorders, he said. The study also included a control group of newborns without MVM and whose mothers had no history of psychotic illness.
As the research progressed, the team noticed that several babies had intracranial hemorrhages visible on their MRI scans but were not suffering any symptoms as a result of these bleeds. The researchers decided to investigate the bleeds further. Gilmore and his colleagues reviewed the mother’s medical records for all the newborns, looking for risk factors such as method of delivery, duration of labor and evidence of maternal or neonatal birth trauma.
“We hypothesized that intracranial hemorrhage would be associated with vaginal birth and not with birth by Caesarean section, with traumatic vaginal birth, such as when forceps or a vacuum was used to assist in delivery, and with prolonged duration of labor,” Gilmore said.
But the researchers did not find any association between intracranial hemorrhage and prolonged duration of labor, or with traumatic or assisted vaginal birth, leading them to conclude that pressure during delivery causes the bleeds.
“In a newborn, the bones of the skull have not fused together, so the bones of the skull can shift and frequently overlap each other during vaginal delivery, to allow the baby’s head to fit through the birth canal. This shifting can compress the brain or cause blood vessels to tear. This would lead to bleeding,” Gilmore said.
In addition, a review of the medical records of the babies born with bleeds found no evidence to suggest that the hemorrhaging had caused any significant problems, Gilmore said.
“There were a few babies that had larger bleeds that may cause problems down the line,” Gilmore said. “We just don’t know at this time what these bleeds may mean over the long term.
“Obviously, the vast majority of the 26 percent of us who were born vaginally and had these types of bleeds are doing just fine. Our brains probably evolved to handle vaginal birth without major difficulty.”
The 88 newborns included in the study, 44 male and 44 female, had MRI scans of their brains done between the ages of 1 week and 5 weeks old. Intracranial hemorrhages were found in 17 babies; seven had two or more types of hemorrhages. All of the newborns with intracranial hemorrhages were delivered vaginally, representing 26 percent of the study’s vaginal births.
Gilmore said the study team planned to conduct follow-up checks on the babies at ages 1 year and 2 years old. “In the future, we will have some sense of whether or not these bleeds have a meaningful impact on a child’s development,” he said.
Gilmore’s co-authors included Dr. Christopher B. Looney, a UNC School of Medicine graduate who is now a radiology resident at Duke University; Dr. J. Keith Smith, UNC assistant professor of neuroradiology; Dr. Lisa H. Merck, a UNC resident in emergency medicine; Dr. Honor M. Wolfe, UNC associate professor of obstetrics and gynecology; Dr. Nancy C. Chescheir, chair of obstetrics and gynecology at Vanderbilt University, formerly of UNC School of Medicine; and Dr. Robert M. Hamer, UNC professor of psychiatry and biostatistics.
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