Sesame Street Girl's Elmo Makes Me Smile Short Sleeve Graphic Tee Shirt, Green. New, With Tags.
This runs a size small, so a 12M would be a perfect fit for a 9M size baby.
This runs a size small, so a 18M would be a perfect fit for a 12M size baby.
This runs a size small, so a 4T would be a perfect fit for a 3T size Toddler.