So, apparently there's some fashion law in Metropolis that says if you adopt a baby that's from a different culture than your own...
...you have to dress like that culture. At least on the cover of your book. And it helps if you're drawn by Dick Giordano (I think he did this cover), too.
I suppose we should be happy that Lois didn't end up with a Chinese or other child of Asian descent... or a black child, or any other cultural background!
There were a lot of DC covers around this time (and, naturally, stories, too), especially in the Superman titles, that made use of Native Americans (or, if you prefer, Indians).
Of course, this particular one was during Lois' "relevance" stage, which never got the press (deservedly so) that Green Lantern/Green Arrow got... in fact, the Lois relevance stories were more often mocked (such as the "I Am Curious (Black)").