Consumption of even low to moderate amounts of alcohol during pregnancy can alter the baby’s brain structure and development, according to a new study.
The yet-to-be peer-reviewed research, to be presented next week at the annual meeting of the Radiological Society of North America (RSNA), analysed MRI exams of 24 foetuses – between 22 and 36 weeks of gestation – with prenatal alcohol exposure.
“Fetal MRI is a highly specialised and safe examination method that allows us to make accurate statements about brain maturation prenatally,” study senior author Gregor Kasprian from the Medical University of Vienna in Austria said in a statement.
Previous studies have shown alcohol consumption during pregnancy can expose the foetus to conditions called foetal alcohol spectrum disorders.
Babies with these conditions could develop learning disabilities, behavioural problems or speech and language delays, scientists said.
“Unfortunately, many pregnant women are unaware of the influence of alcohol on the foetus during pregnancy,” study lead author Patric Kienast said.
In the study, researchers determined alcohol exposure via anonymous surveys of the mothers.
Scientists found that in foetuses with alcohol exposure, the right superior temporal sulcus (STS) – a brain region involved in social cognition, audiovisual integration and language perception – was shallower.
“We found the greatest changes in the temporal brain region and STS. We know that this region, and specifically the formation of the STS, has a great influence on language development during childhood,” Dr Kasprian said.
Researchers found brain changes in foetuses even at low levels of alcohol exposure.
“Seventeen of 24 mothers drank alcohol relatively infrequently, with average alcohol consumption of less than one alcoholic drink per week. Nevertheless, we were able to detect significant changes in these foetuses based on prenatal MRI,” Dr Kienast said.
The survey revealed that three mothers drank one to three drinks per week, and two drank four to six drinks per week.
One of the mothers consumed an average of 14 or more drinks per week while six others also reported at least one binge drinking event – exceeding four drinks on one occasion – during pregnancy.
Scientists suspect delayed foetal brain development could be specifically related to a delayed stage of myelination – a process critical to brain and nervous system function.
Myelin is an insulating layer around nerves that allows them to transmit information faster.
Previous studies have suggested that developmental milestones in infants, such as rolling over, crawling and language processing are linked to myelination.
Scientists also suspect that delayed brain development in foetuses could be linked to less formation of folds in the brain’s frontal lobe that could affect cognitive performance.
“Pregnant women should strictly avoid alcohol consumption. As we show in our study, even low levels of alcohol consumption can lead to structural changes in brain development and delayed brain maturation,” Dr Kienast said.
Researchers said further studies can unravel how these structural changes in the brain will affect development in these babies after birth.