Raw seafood—the main ingredient in ceviche—is a no-go during pregnancy. The reason (like most on the "avoid" list) boils down to food safety.
Raw and/or undercooked animal protein serves as a very appealing host for harmful bacteria like E. Coli, Salmonella, and Listeria, all of which cause foodborne illness. Food poisoning is something pregnant people have to take more seriously, as they’re considered immune-compromised and are therefore at a greater risk for more severe illness. To protect the health of both mom and baby, wait until after giving birth to enjoy ceviche.