I live in NC, things vary by state...but most WIC programs are pretty much the same as far as missed appointments and policies and such.
Anyways, to answer your question: I've missed a WIC appointment before, back in Indiana, and there was no problem. I explained why I missed the appointment (which was due to a scheduling conflict at work with an important meeting) and they rescheduled me for the class. It was probably the same class you were supposed to take. I've missed a follow-up or two here in NC and there was not any problem. The one time, I was 2 weeks late, my checks were not the full package for that month, but there was no continual penalty; I got roughly half of my package for that month because the month was half gone.
Don't worry. Call them on Monday morning, explain the situation and all should be fine. There should be no need to re-apply or any of that mess. I seriously doubt they will make you go through all of that or that they will try and terminate your WIC. Of course, all states are a little bit different, but they are all mostly the same.
And if, by some crazy chance, they have terminated your WIC...you will be able to re-apply. Like I said, don't stress over it. You've got enough stress just being pregnant. Call them on Monday and be honest about why you missed your appointment. Tell them about being sick and being on bed rest. WIC are good people; they are there to help you, not screw you out of anything.