Why does my baby have weltlike red blotches?

Baby rash. When babies are born, they are taken from their moist environment in the womb, the protective coating for their skin is wiped off, and they join our dry environment. A baby's sensitive skin can get many rashes that go away easily. The red blotches are probably due to a common baby rash with a complicated name -erythema toxicum neonatorum. Red blotchy rash works better. Moisturize well.