One-Quarter of Vaginal Births Cause Tiny Brain Hemorrhages

"There was no association with any of these we thought might be risk factors," said Gilmore. "It seems like it's just the process of being born."

He added that a newborn's skull isn't yet fully formed, so it can compress during delivery. That compression may cause small tears in the baby's blood vessels.

But, Gilmore said there was no evidence that the small bleeds cause any problems. To be sure, he said, they'll follow the babies' progress over the next few years.

Dr. William Blessed is director of maternal-fetal medicine at Providence Hospital and Medical Center, in Southfield, Mich. He called the new research "a very good study, but with small numbers."

"I think this has probably been going on all along. I don't think the prevalence is increasing," Blessed said, adding that the information from this study may help doctors with liability issues. "In the past, people always thought if there was a hemorrhage, the doctor must have done something wrong. Now, you see you can have intracranial hemorrhage without [cause]; it can occur in a normal birth."

Blessed said he's concerned that some patients may want to have C-sections because of this study. He said it's important to remember that these findings were "clinically insignificant."

C-sections, on the other hand, carry known risks because it's a major surgery. "While the risk of complications from C-sections have greatly diminished, there are risks. Some patients do have complications," Blessed said.

More information

Visit the U.S. National Women's Health Information Center to learn more about the labor and delivery process.

SOURCES: John Gilmore, M.D., professor of psychiatry, University of North Carolina School of Medicine, Chapel Hill; Honor Wolfe, M.D., associate professor of obstetrics and gynecology, University of North Carolina School of Medicine, Chapel Hill; Keith Smith, M.D., associate professor of neuroradiology, University of North Carolina School of Medicine, Chapel Hill; William Blessed, M.D., director, maternal-fetal medicine, Providence Hospital and Medical Center, Southfield, Mich.; February 2007,Radiology