Normal Vaginal Births Cause Infant Brain Hemorrhages

January 30, 2007

CHAPEL HILL, N.C. -- Intracranial bleeding in newborns has been found common after a vaginal birth, although the bleeding is limited and apparently has no effect, according to researchers here.

CHAPEL HILL, N.C., Jan. 30 -- Intracranial bleeding in newborns has been found common after a vaginal birth, although the bleeding is limited and apparently has no effect, according to researchers here.

In a study using magnetic resonance imaging, about one infant in four delivered vaginally had at least one form of intracranial hemorrhage, found John Gilmore, M.D., of the University of North Carolina School of Medicine, and colleagues.

MRI did not show signs of bleeding for babies born by caesarian delivery, they reported in the February issue of Radiology.

"Small bleeds in and around the brain are very common in infants who are born vaginally," Dr. Gilmore said. "It seems that a normal vaginal birth can cause these small bleeds."

But he added that although more research is needed on the implications of the hemorrhages, vaginal birth has not suddenly become unduly risky.

"Obviously, the vast majority of us who were born vaginally and may have had these types of bleeds are doing just fine," he said. "Humans have been born vaginally for a very long time, and our brains probably evolved to handle vaginal birth without major difficulty."

Intracranial hemorrhage in full-term infants is usually associated with symptoms such as apnea, bradycardia and seizures, Dr. Gilmore and colleagues said, and a range of factors has been suggested to account for the bleeding, including prolonged labor and assisted delivery.

But for this study, the researchers studied 88 asymptomatic newborns, evenly divided between male and female, of whom 65 were delivered vaginally and the remainder by caesarian.

The babies were studied using a 3-Tesla MR machine, without anesthetic, between the ages of one and five weeks, the researchers said.

Analysis found that:

  • Seventeen of the babies -- or 26% of the cohort -- had bleeding, including 16 subdural, two subarachnoid, one intraventricular, and six parenchymal hemorrhages.
  • Seven infants had two or more types of bleeding.
  • None of the infants with bleeding had been delivered by C-section.
  • Intracranial bleeding was significantly associated with vaginal birth (at P