Vaginal Birth Raises Hemorrhage Risk in Newborns

"Small bleeds in and around the brain are very common in infants who are born vaginally, said John H. Gilmore, M.D., professor of psychiatry and vice chair for research and scientific affairs at the University of North Carolina School of Medicine (Chapel Hill; NC, USA). "It seems that a normal vaginal birth can cause these small bleeds.”

For the study, which was published in the February 2007 issue of the journal Radiology, 88 asymptomatic infants, equally divided between male and female, underwent MRI between the ages of one and five weeks. Sixty-five had been delivered vaginally and 23 had been delivered by cesarean section. MR images showed that 17 (26%) of the infants who had been delivered vaginally had intracranial hemorrhages (ICHs), or small bleeds in and around the brain. Seven infants had two or more types of ICH. Earlier studies have shown a smaller incidence--approximately 10%--of intracranial hemorrhage associated with vaginal birth.

Whereas ICH was significantly associated with vaginal birth, it was not dependent on prolonged duration of labor or on traumatic or assisted vaginal birth. "In our study, 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,” Dr. Gilmore said. "The bleeds are probably caused by pressure on the skull during delivery.”

In a newborn, the bones of the skull have not yet fused and therefore the bones of the skull can shift and frequently overlap each other during vaginal delivery, to allow the infant's head to fit through the birth canal.

Most of the ICHs identified were very small subdural hematomas (bleeding between the brain and the thick membrane that covers the brain below the skull) and most of them were located in the lower, back part of the brain over the occipital lobe or the cerebellum, which is below the occipital lobe.
Typically, small bleeds resolve over time without causing problems, although larger ones may cause problems later in the child's life, including seizures, subtle learning problems, or problems with motor development.

Further studies must be performed to assess the long-term effects of ICH in infants, but Dr. Gilmore noted that expectant parents should not rule out vaginal delivery because of these findings.




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