
Jay D. answered 04/28/19
Undergraduate Honors Student Majoring in French Secondary Ed.
It's really a question of use, like you said. In general, we say "children's clothing," not "child clothing," even though the latter isn't technically wrong in a grammatical sense. Note the possessive: not "children clothing," but "children's clothing." The same goes for, say, "men's clothing" or "women's clothing." I guess "baby clothing" is kind of an outlier in this regard.
Though overall, for this sentence, I think it would be best just to say "clothes" or "clothing," since the reader still knows who they're for. If you said you bought clothing for a baby, I'd automatically assume you bought baby clothes. I mean, it would be silly to buy adult clothes for a baby to wear, you know?