Question about beta hcg numbers?

I know the numbers are supposed to double every few days. My question is, when you get your results and they've doubled, does that mean you're "out of the woods" so to speak--as far as miscarriage, blighted ovum, etc.? I had my bloodwork done on Thursday, and it was 2800. I had it re-tested today, and will get the results tomorrow. If it's good, am I safe to ume that everything will be okay from here on out? How often will I have to go back to have the same test done? I have a call in to my doctor's nurse. Just wanted to get some opinions here, too. :)