Pregnant women that I know who are Japanese say that they do not eat this during pregnancy. Also the nori rolls you see en masse at the local shopping cenbtre food court sit there for hours and are pre prepared. Japanese women make their own and eat it. It's vastly different.
Are these Japanese women, here in Australia or in Japan? - The reason i ask is because i wonder if it is because they are advised here of the dangers of listeria whereas maybe in Japan its not as widely versed? - Im just curious!