As you know, one of the aims of the BiSC project is to investigate the effects of early exposure to various environmental factors on fetal neurodevelopment. During the follow-up of the project volunteers, a complete ultrasound was performed to collect parameters of the fetal brain anatomy at the 3rd trimester visit at each of the collaborating hospitals: Hospital de Sant Pau i la Santa Creu, Hospital Clínic – The Maternity Hospital and Sant Joan de Déu Hospital. This test is performed in the third trimester (around week 32 of gestation) because this is the period when the primary brain structures are already formed and beginning to mature. In fact, in the third trimester most of the fetus’s organs are already practically formed, but the nervous system, due to its high level of functional complexity and despite having started its development in the third week of pregnancy, still needs a long period of structuring and maturation that continues even after the baby is born.

The human brain during fetal development. Source: Lindsey Konkel, 2018, Environmental Health Perspectives.

Thus, the follow-up neurosonography consisted of a thorough examination to assess the structural integrity and level of maturity of the fetal brain, as well as to detect any abnormalities of the central nervous system.

In order to extract the results of this neurosonographic evaluation, we had to measure the different parameters of interest in each of the images captured during the ultrasound. The images below are an example of some ultrasound sections of the fetal brain, where different anatomical structures are observed, such as the corpus callosum, which is made up of neuronal bodies (collectively called “white matter”) that connect the two hemispheres cerebral Subsequently, we implemented a quality control process to evaluate the data resulting from these measurements and detect errors before proceeding with the analysis.

Echographic images of the neurosonography performed in the BiSC project. 1. Axial section of the fetal brain with Doppler signal of the middle cerebral artery. 2: Sagittal section of the fetal brain where the corpus callosum can be seen. 3. Axial section of the fetal brain where the cerebellum can be seen.


Finally, from the 1081 volunteers participating in the study, we were able to extract a total of 956 fetal neurosonographic assessments from the third trimester. This is a spectacular number that will allow us to study how different factors in the environment of pregnancy, such as exposure to atmospheric pollution, can influence the delicate process of maturation of the brain structures of babies before they are born.

That’s why we want to thank all the volunteers who agreed to do this test altruistically!


This news has been written by Laura C. Gómez Herrera, predoctoral student of the BiSC project.