Personalized Superhero 4th Birthday Pink Baby Bodysuit. Happy 4th birthday! Celebrate your toddler's third b-day with this cute I'm 4 pink superhero design. Happy Birthday four-year-old! Our unisex one piece baby bodysuit make great gift for newborns, babies, infants, baby showers and expectant moms. An ideal gift for any new parent who will want one in every color.