Vaginal birth increases the risk of brain haemorrhage in newborns, a new study suggests. But it is unclear if the early bleeding causes problems with subsequent child development, so natural births should not be eschewed in favour of caesarean sections, experts warn.
Psychiatrists at the University of North Carolina at Chapel Hill, US, were studying normal brain development in babies as part of their research on schizophrenia when they noticed that some of the newborns had suffered small haemorrhages. 鈥淭he bleeds were unexpected,鈥� says John Gilmore, who led the study. 鈥淪o we decided to see what they were correlated with.鈥�
The researchers looked at 88 newborns with no outward symptoms, recording information including whether the birth was vaginal or caesarean, the duration of labour, and the infant鈥檚 weight, head size and gestational age at birth.
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They found that 26% of the babies born vaginally had bleeding in the brain, while none of those born through caesarean were affected. No other risk factor seemed to be involved. 鈥淚t鈥檚 purely the process of being born and going through the birth canal,鈥� says Gilmore.
Past studies have linked haemorrhages to the trauma of birth, but these involved babies with clear symptoms such as seizures or lethargy.
Tiny amounts
One previous study looked at newborns with no symptoms and found 8% of them had some bleeding from their brains. But Gilmore鈥檚 team used a magnetic resonance imaging (MRI) scanner with better resolution. 鈥淭he MRI they鈥檙e using is so sensitive they鈥檙e catching very tiny amounts of blood,鈥� says Carol Rumack, a paediatric radiologist at the University of Colorado in Denver, US.
The haemorrhages Gilmore found were mostly subdural 鈥� meaning the blood pooled outside the brain, rather than within the tissue. Infant skull bones should be able to flex to accommodate the extra pressure from subdural haemorrhages, Rumack says.
The bleeding may correlate with other problems that may emerge only later on, however. 鈥淚t will be very important to follow these babies鈥� development,鈥� says Rosemary Higgins, a neonatologist with the National Institute of Child Health and Human Development in Bethesda, Maryland, part of the US National Institutes of Health (NIH).
Mothers in the west are increasingly choosing caesarean births and Gilmore鈥檚 study could contribute to that trend. But Higgins warns that this would be premature.
In March 2006, an NIH panel considered the issue of elective caesarean sections, concluding that much more research is needed to evaluate the benefits and risks to mothers and babies (see Confusion over the choosing of caesarean births).
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