S.H.
I would say and do nothing.
Because, something like that is very hard.
My friend lost a baby late term.
I didn't even know.
I had not seen her in awhile etc.
And it is a very private ordeal.
One day I saw her, and then she told me.
But she had been under the radar, until then.
Understandably.
Getting "attention" about it, may or will just make it harder... why? Because, each time a person may say something about it, even if nice, it will just make her go through all of those emotions again and about what happened and the sequence of events that led up to it.
I had a miscarriage once. But it was at 6 weeks.
But, I DID NOT want to tell anyone. Nor have anyone ask me about it... because, each time a person asked me about it and told me their story about it... it took a LOT out of me and I then had to tell each person what happened, yes I'm sad, and live through all of that... again and again.
Grief, is a private thing.
And at least for me, each time someone even out of kindness said something to me, it just made me sadder and my own "recovery" about it, was then dragged back to square one. Again. And I had to relive everything, again.
My Husband didn't even like to think about it. He was very sad as well. But he didn't show it.
You can just give her a hug. And she will know why.
No words have to be exchanged.
Just a silent heartfelt, hug.
If that.
Because as you said, she is an acquaintance. Not a BFF.
... if someone told me "I heard what happened....." to me when I had my miscarriage, I would not feel good about that. It means, the gossip vine is telling "her" story all over the place. And that is not stress a person needs.
Anyway, that is just my own personal feelings.