Complicated New Hire

Have someone i hired that "didn't know she was pregnant". I did not notice during interview do to desk/equipment obstructions. However the following day I immediately noticed. Due to the nature of the job (heavy lifting and mostly standing during whole shift) I wanted to confirm she was ok to be doing it but since she didnt say she was pregnant I was worried about the legalities of my asking. So I waited and tried to do some research on if I can ask.

Technically I found I am not supposed to but I talked to her and told her my concerns. She confirmed she was pregnant however didnt say how far along she was. (I was guessing at least 5 months) Settled with the idea In about 4 months another employee will return back to work by then and all will be well while she recovers.

During the next two weeks of training im constantly reminding her of things I've already said with how to do the job. She had transportation issues (which transportation was one of job requirements) she called out 2x andb she suprised me day of about an appt that required to leave shift early. Quickly decided this wasn't working out and I would start looking for a replacement.

Fast forward to today, her water broke while at work. And according to internet and a couple other moms I know they tell me im looking at 6 weeks she will be out recovering from birth. I can not go that long without help in the shop (small shop only 3 workers including myself)

So now I know I have to find a replacement but what are my options for not bringing her back?

Location: Delaware

edit to include this is not her first child. She has 3-4 others. However, this is my first pregnant employee