Fetuses experiencing restricted fetal growth exhibit less development in crucial brain structures
A study conducted by the Institut de Recerca Sant Joan de Déu - SJD Barcelona Children's Hospital reveals that small fetuses diagnosed with late-onset growth restriction show a decrease in the length of specific brain structures compared to fetuses with appropriate size for their gestational age. The findings have been published in the scientific journal Ultrasound in obstetrics & gynecology.
Late-onset small fetuses are those that manifest restricted fetal growth after 32 weeks of gestation. This indicates that the fetus is not growing adequately and is smaller than expected for its gestational age in comparison to the general population. Currently, according to the World Health Organization (WHO), the incidence of this condition ranges from 3 to 7 percent of pregnancies worldwide.
"We are aware that small fetuses face a higher long-term risk of neurodevelopmental disorders. Therefore, it is crucial to possess tools for identifying fetuses at greater risk in order to implement early interventions that enhance their prognosis," explains Dr. Lola Gómez-Roig, coordinator of the Environment and Complications in Pregnancy group at IRSJD and head of the Obstetrics and Gynecology Department at SJD Barcelona Children's Hospital.
Brain structures in restricted fetal growth
The research team observed that smaller fetuses also displayed reduced development in two brain structures: the fastigium-callosum and the tectum. Both structures play significant roles in brain and nervous system development.
The corpus callosum is a band of nerve fibers that connects the two cerebral hemispheres, facilitating communication between them. The fastigium is situated in the cerebellum and is responsible for motor coordination and balance. Lastly, the tectum is a structure located in the midbrain that is involved in visual and auditory perception.
"By utilizing neurosonography during the third trimester, we measured the length between the fastigium and the corpus callosum, as well as the length of the tectum in fetuses with growth restriction and fetuses with normal weight. We observed lower measurements in small fetuses. Furthermore, we were able to analyze the results within two subgroups based on the severity of fetal growth restriction, and the differences remained consistent," states Dr. Míriam Pérez-Cruz, researcher in the Environment and Complications in Pregnancy group and coordinator of the study. "Advanced fetal neurosonography is an ultrasound scan that can identify brain abnormalities and subtle changes, carrying no risk for either the mother or the baby."
Neurosonography is an ultrasound technique that allows comprehensive examination of the brain and spinal structures from the early stages of gestation. The procedure employs an ultrasound transducer placed transabdominally and transvaginally, and it can be conducted by expert sonographers starting from the 13th week of gestation. Typically performed during the second or third trimester of pregnancy, it can detect brain irregularities such as malformations, hemorrhages, microcephaly, and more.
The study's results hold significant clinical implications, suggesting that measuring the length of the fastigium-body callosum and tectum could assist in identifying fetuses at heightened risk of neurodevelopmental complications due to restricted fetal growth.
"Early identification of these fetuses can facilitate timely interventions that improve their prognosis. Furthermore, we have demonstrated the reliable use of these measurements in clinical practice, given the highly significant results. This can positively impact prenatal and neonatal care for babies with restricted fetal growth," concludes Dr. Míriam Pérez-Cruz. "Moreover, if in the future we can establish an association between the size of these structures and neurodevelopment, we could employ this data as biomarkers in screening tests for at-risk populations."
Reference paper
Lip-Sosa DL, Pérez-Cruz M, Ahumada-Droguett P, Ribas-Prats T, Puertollano M, García-Gómez MA, Mazarico E, Eixarch E, Escera C, Gómez-Roig MD. Corpus callosum-fastigium and tectal lengths in late-onset small fetuses. Ultrasound Obstet Gynecol. 2023 Feb 1. doi: 10.1002/uog.26169. Epub ahead of print. PMID: 36722073.
