Article 5 of Uruguay Decree 121/989 (attached at the end of the PDF on Uruguay’s 2009 National Traffic Regulations):
“In any motor vehicle with more than two wheels, minors under 12 years of age inclusive, may ride only in the rear seats.”
Law 19.061. Provisions relating to the transport and restraint of children and adolescents in vehicles.
The first article establishes the obligation for children between 0 and 12 years of age to travel in the rear seats with the restraint systems established, as well as any child measuring less than 1.50 meters. According to Article 3, such devices must comply with the relevant regulations.