I had a white baby doll dress that had pink and blue smocking and floppy cap sleeves. As with all baby doll dresses, mine was incredibly short. I used to wear my hair in bunches with white ribbons and my make-up bright and doll-like.
It's thought that babydolls were popularised by the 1956 film Baby Doll starring Carroll Baker. Nowadays it is associated with negligee, as many are made of chiffon, lace or trimmed with marabou, despite the connatations of being worn by babies/young children. In the early to mid 90s, people like Courtney Love and Riot Grrrl grungsters took on babydoll dresses as part of their look.