It’s a Native American tradition that babies are named after the things the parents see around them when they give birth. Sara Leisten of Gothenburg, whose baby was born with one arm in the air, in the manner of superman. So baby Leisten was named “Staalman”, Swedish for “Man of Steel“.
The Swedish authorities however are very strict on baby-naming and Staalman was rejected. In the UK, “Superman” is perfectly acceptable and there have been two babies with the name since 1984.