What an MRI Study Reveals About Low Alcohol Use During Pregnancy and Fetal Brain Structure

Researchers found that even low amounts of alcohol consumption in pregnant women can lead to early and diffuse structural changes in brain regions related to key functions including language development.

Alcohol consumption that amounts to less than one alcoholic beverage per week during pregnancy can change fetal brain structure and delay brain development, according to a fetal magnetic resonance imaging (MRI) study presented at the Radiological Society of North America (RSNA) 2022 Annual Meeting.

“Identification of the teratologic toxic effects on human brain development opens new diagnostic opportunities for fetal neuroradiology, allowing early postnatal support programs in these cases and stimulating the discussion of alcohol prevention during pregnancy to promote public health,” wrote Gregor Kasprian, M.D., an associate professor of radiology in the Department of Biomedical Imaging and Image-Guided Therapy at the Medical University of Vienna in Austria, and colleagues.

While alcohol consumption during pregnancy has been shown to affect fetal brain development, early structural alterations of this development have not been systematically studied. In this prospective single center study, the researchers used fetal MRI to assess the effects of alcohol exposure on brain development.

They analyzed MRI exams of 24 fetuses with prenatal alcohol exposure who were at 22 to 36 weeks of gestation at the time of MRI. Alcohol exposure was determined via two anonymous questionnaires: the Pregnancy Risk Assessment Monitoring System (PRAMS), a surveillance project of the Centers for Disease Control and Prevention and health departments, and the four-question T-ACE Screening Tool. The average alcohol consumption was less than one alcoholic drink per week, according to the study.

The MRI exams of 20 fetuses were included in the final analysis and were 1:1 age matched to healthy controls. Brain maturation was assessed by using the fetal total maturation score (fTMS) based on super-resolution-postprocessed T2-weighted/steady state free precession (SSFP) sequences in three planes (1.5T). Temporal and occipital sulci depth and brain asymmetry expression in the temporal lobe were also quantified.

Compared with the controls, fetuses exposed to alcohol had a significantly lower fTMS score and a shallower right superior temporal sulcus (STS), a region involved in social cognition, audiovisual integration, and language perception.

"We found the greatest changes in the temporal brain region and STS," noted Dr. Kasprian. "We know that this region, and specifically the formation of the STS, has a great influence on language development during childhood."

Further, the delayed fetal brain development could be specifically related to a delayed myelination stage and less distinct gyrification in the frontal and occipital lobes.

"Pregnant women should strictly avoid alcohol consumption," said lead author Patric Kienast, M.D., a Ph.D. student in the Department of Biomedical Imaging and Image-Guided Therapy in the Division of Neuroradiology and Musculoskeletal Radiology at the Medical University of Vienna. "As we show in our study, even low levels of alcohol consumption can lead to structural changes in brain development and delayed brain maturation."

To assess how these structural changes will affect brain development, “we need to wait for the children who were examined as fetuses at that time to get a little older, so that we can invite them back for further examinations," said Dr. Kienast. "However, we can strongly assume that the changes we discovered contribute to the cognitive and behavioral difficulties that may occur during childhood."