I agree that it is likely going to be in the season finale. The birth probably does come first, and just as they sigh with relief this other tragedy happens. That is the pattern, I think. ABC may tease that there are deadly plans or that a sinister foe etc for other episodes but I do think it is in the finale, maybe the end of 321 so midway through the 2 hours.
Also we do not seem to know who is in studio. We know who has been seen filming outdoors, so that does imply those people are safe up to that point but we do not know the sequence within the episode if there is any studio filming.
I am ready for it to be anything. The only thing I hope is they can manage to write it well enough that it is touching not just shocking. If it feels like “twist for the sake of it” and tossing aside the bigger themes of hope, second chances and family, it is really going to be difficult to muster the enthusiasm to keep watching. Fairytales do have danger, but what I like is the glimmer that things can get better if we hang onto our hope.
“If I had a world of my own, everything would be nonsense. Nothing would be what it is, because everything would be what it isn't. And contrary wise, what is, it wouldn't be. And what it wouldn't be, it would. You see?” -- Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass