According to a new study published in the American Journal of Roentgenology (AJR), third-trimester fetuses with in-utero opioid exposure exhibited multiple smaller 2D biometric measurements of the brain, as well as altered fetal physiology, on investigational MRI.

Noting the scarcity of imaging literature evaluating prenatal opioid exposure on brain development, first author Usha D. Nagaraj, MD, from Cincinnati Children’s Hospital Medical Center in Ohio, said: ‘Our findings demonstrate the impact of prenatal opioid exposure on fetal brain development, which may, in turn, affect postnatal clinical outcomes.’

Nagaraj and colleagues’ prospective multicenter case-control study included 65 women (mean age, 29 years) in their third trimester of pregnancy who underwent fetal MRI from July 1, 2020 through December 31, 2021 at three US academic medical centres: Cincinnati Children’s Hospital Medical Center, Arkansas Children’s Hospital, and the University of North Carolina at Chapel Hill. A total of 28 fetuses (mean gestational age, 32.3 weeks) were classified as opioid-exposed, while 37 fetuses (mean gestational age, 31.9 weeks) were unexposed in utero. Fourteen 2D biometric measurements of the fetal brain were manually assessed and used to derive four indices.

When adjusting for gestational age, fetal sex, and nicotine exposure, 7 of the 14 2D biometric measurements – cerebral frontal-occipital diameter, bone biparietal diameter, brain biparietal diameter, corpus callosum length, vermis height, anterior-posterior pons measurement, and transverse cerebellar diameter – were significantly smaller in opioid-exposed fetuses than in unexposed fetuses, as measured on fetal MRI.  

‘Fetuses with prenatal opioid exposure had increased frequencies of breech presentation and of increased amniotic fluid volume,’ the authors concluded.