Tight-fitting elastic underwear with high slit, because jumpsuits are high slit, avoid exposing both sides of underwear and don't wear loose underwear.

The color of underwear depends on the color of jumpsuit, in short, it can't be transparent. Children's jumpsuits are mostly single layer spandex, which is easy to penetrate. If it is lined with cotton and ammonia, you don't have to worry about the color.