Tuesday, February 06, 2007

Brain hemorrhage after vaginal delivery

A study published this month in the journal Radiology is generating a lot of discussion. The study is Intracranial Hemorrhage in Asymptomatic Neonates: Prevalence on MR Images and Relationship to Obstetric and Neonatal Risk Factors, Looney et al., Radiology 2007;242:535-541.
Purpose: To retrospectively evaluate the prevalence of neonatal intracranial hemorrhage (ICH) and its relationship to obstetric and neonatal risk factors...

Pregnant mothers were recruited from December 2002 to July 2005 as part of an ongoing prospective study about the investigation of prenatal and neonatal brain development. The cohort included control neonates and two groups of neonates at high risk for psychiatric or neurodevelopmental disorders ...


One hundred eighteen neonates were imaged in the parent study; 97 had undergone MR imaging between the ages of 1 and 5 weeks after birth. Nine neonates were excluded from this analysis because a T1-weighted sequence was not performed. The final 88 (44 male and 44 female) neonates in our study included 69 control neonates without risk for psychiatric or neurodevelopmental disorders (four from twin pregnancies), 12 neonates with prenatal MVM, and seven offspring of mothers with schizophrenia. Among the 88 neonates, maternal ethnicity was as follows: 69 (78%) were white, 16 (18%) were African American, and three (4%) were Asian American. Mean maternal age was 28.6 years ± 5.3. In 65 (74%) of neonates, delivery was vaginal; in 23 (26%), delivery was cesarean...

Risk Factors
All 17 hemorrhages occurred in full-term neonates delivered through vaginal birth and yielded a prevalence of 26% in vaginal births. Since all hemorrhages occurred in vaginally delivered neonates, the neonates born with cesarean delivery were excluded from the subsequent analysis of other obstetric and neonatal risk factors. Vaginal birth was the only significant risk factor associated with ICH (P < .005). Mothers of neonates with ICH were not more likely to have had assisted vaginal delivery or vaginal, labial, or perineal lacerations. Newborns with ICH were not more likely to have had evidence of birth trauma...


We found that 26% of asymptomatic neonates delivered vaginally had ICH at MR imaging, and this finding suggests that ICH is a fairly common consequence of a normal vaginal delivery. ICH has been thought to be unusual in full-term neonates, though the results of this study and those of the study of Whitby et al suggest otherwise.

ICH in full-term neonates often has been associated with birth trauma, which is an association that results from the reporting of hemorrhages identified with cranial imaging in symptomatic neonates in case reports, case series, and case-control studies. In our study, neither assisted vaginal delivery nor evidence of neonatal birth trauma could be used to predict the presence of ICH; most (13 of 17, 76%) of the cases of ICH were in the setting of nonassisted vaginal birth. This finding is in agreement with that of Whitby et al, who described nine neonates with asymptomatic hemorrhage; in six of the nine neonates, hemorrhage was associated with assisted delivery; in only two of nine neonates with subdural hemorrhages, external birth trauma was an associated finding. The authors concluded that a subdural hematoma was not necessarily associated with obvious birth trauma. Holden et al identified four of 11 neonates with clinically silent ICH; in all, vaginal delivery was uneventful.

The majority of the ICHs in our study were subdural, and most were infratentorial. Subdural hematomas can result from tears in the tentorium, falx, or bridging veins during labor. Subdural hematoma location may be an important determinant of symptoms, as findings of this study and those of the study of Whitby et al suggest that peritentorial subdural hematomas occur frequently and without immediate clinical consequence. Alternately, even small amounts of subdural hemorrhage in the posterior fossa may lead to obstructive hydrocephalus or neurologic deficits...

The high prevalence of ICH in our asymptomatic population is important for several reasons. Our findings indicate that vaginal birth may be inherently traumatic to the neonatal brain and can result in a spectrum of ICHs, which include subdural hematomas and subarachnoid, intraparenchymal, and germinal matrix hemorrhages. Holden et al pointed out that retinal hemorrhage also is observed in 20%–40% of newborns and that red blood cells often are found in the cerebrospinal fluid of newborns, and these findings indicate that there is trauma after vaginal birth. The long-term consequences of these hemorrhages are unknown at this time, though it is likely that small subdural hemorrhages resolve quickly without substantial consequence.

It is possible, however, that some of these incidental ICHs that occur after vaginal birth may have long-term consequences for subsequent neurocognitive development or may contribute to the development of "idiopathic" epilepsy. These incidental hemorrhages also may increase the risk for complex multifactorial neuropsychiatric disorders such as schizophrenia, which has been associated with perinatal birth complications. In addition, ICH may be a marker of traumatic forces that could cause more subtle injury to the developing brain that would not be apparent on MR images; examples of these traumatic forces are transient ischemia or white matter tract damage, which would also affect subsequent neurodevelopment. We plan longitudinal follow-up of this cohort, and the findings from this follow-up may suggest answers to these important questions.

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