Summary: Pregnant women who consume small-to-moderate amounts of alcohol during pregnancy risk altering their baby’s brain structure and slowing prenatal brain development.
Source: RSNA
A recent fetal MRI study shows that alcohol intake during pregnancy—even at low or moderate levels—can change the structure of the developing brain and delay aspects of maturation. The findings are being presented at the Radiological Society of North America (RSNA) annual meeting.
“Fetal MRI is a highly specialized and safe exam that allows us to assess brain maturation before birth,” said study senior author Gregor Kasprian, M.D., associate professor of radiology in the Department of Biomedical Imaging and Image-guided Therapy at the Medical University of Vienna. The study used advanced MRI measures to compare brain development in fetuses with reported prenatal alcohol exposure and in age-matched controls.
Alcohol exposure during pregnancy is linked to a spectrum of conditions known as fetal alcohol spectrum disorders (FASD). Children affected by these conditions can experience learning difficulties, behavioral challenges, and delays in speech and language. The new MRI findings offer prenatal evidence that structural brain changes associated with alcohol exposure can be detected before birth.
“Many pregnant women are not fully aware of how even small amounts of alcohol can affect the fetus,” said lead author Patric Kienast, M.D., a Ph.D. student in the Department of Biomedical Imaging and Image-Guided Therapy, Division of Neuroradiology and Musculoskeletal Radiology at the Medical University of Vienna. “It is our responsibility not only to conduct this research but also to inform and educate the public about these risks.”
For the study, researchers analyzed fetal MRI scans from 24 pregnancies with reported prenatal alcohol exposure. Scans were performed when the fetuses were between 22 and 36 weeks’ gestation. Alcohol exposure was assessed using anonymous maternal questionnaires: the Pregnancy Risk Assessment Monitoring System (PRAMS), a surveillance tool used by public health agencies, and the T-ACE screening tool, a brief four-question measure that identifies risk drinking during pregnancy.
Compared with matched controls, fetuses with prenatal alcohol exposure showed a significantly lower fetal total maturation score (fTMS) and a shallower right superior temporal sulcus (STS). The STS is an anatomical feature involved in social cognition, audiovisual integration and language perception. The greatest differences were observed in the temporal region of the brain, particularly affecting the formation of the STS, a structure known to play an important role in language development during early childhood.
Importantly, alterations were detectable even at low reported levels of drinking. Seventeen of the 24 mothers reported drinking relatively infrequently, with average alcohol intake of less than one standard drink per week. Despite this low reported intake, MRI assessments revealed measurable differences in fetal brain structure. Three mothers reported consuming one to three drinks per week, two reported four to six drinks per week, and one reported an average of 14 or more drinks per week. Six mothers reported at least one binge drinking episode (defined as more than four drinks on one occasion) during pregnancy.
Researchers noted that delayed fetal brain development observed in the study could reflect a slowed stage of myelination and less distinct gyrification in frontal and occipital regions. Myelination is the process by which nerve fibers are insulated with myelin, improving the speed and efficiency of neural signaling. This process is crucial for early motor and cognitive milestones such as rolling over, crawling, and the initial stages of language processing.
Gyrification describes the folding of the cerebral cortex. These folds increase cortical surface area within the limited space of the skull and support higher cognitive function. Reduced or delayed gyrification can be associated with diminished functional capacity in affected regions.
“Pregnant women should avoid alcohol completely,” Dr. Kienast emphasized. “Our results demonstrate that even low levels of alcohol consumption can produce structural changes and delay brain maturation detectable by prenatal MRI.”
It remains to be determined how these prenatal structural differences will translate into postnatal development and long-term outcomes. The research team plans to follow the children who underwent fetal MRI, inviting them for follow-up assessments as they grow older to better understand potential cognitive or behavioral impacts.
“Longitudinal follow-up is essential to determine the practical implications of the structural changes we identified prenatally,” Dr. Kienast added. “However, based on existing knowledge about brain regions involved and the types of changes we observed, it is reasonable to expect that these alterations could contribute to the cognitive and behavioral difficulties reported in children with prenatal alcohol exposure.”
Co-authors on the study include Marlene Stuempflen, M.D., Daniela Prayer, M.D., Benjamin Sigl, M.D., Mariana Schuette, M.D., Ph.D., and Sarah Glatter, M.D., M.M.Sc.
About this alcohol and brain development research news
Author: Linda Brooks
Source: RSNA
Contact: Linda Brooks – RSNA
Original Research: Findings presented at the 108th Scientific Assembly and Annual Meeting of the Radiological Society of North America