As a consequence, the 21-year-old man's first workday at the preschool was also his last, Göteborgs-Posten (GP) reported on Wednesday.
The preschool principal received a tip on Monday morning about the Twitter posts.
"I informed the parents. Some chose to pick their children up earlier. Later, I called the police and asked if they could trace the message. When I read it, they thought it was very serious, so they came here," the principal told GP.
The principal continued following the Twitter feed, on which the substitute teacher also wrote, "Haha. A little girl thought my name was Max. That was too cute *smile*"
"Got myself out of changing diapers all day. Pooh", read a later post, followed by "Finishing at 5:30pm. Dying."
The principal suspected the new substitute teacher since the Tweets appeared during the man's coffee and lunch breaks. The principal said police took the man in for questioning.
The substitute teacher confessed immediately and is now under suspicion of being a threat to groups and may not be able to return to his temporary position.
Following the police interrogation, the man was subsequently released.