When are the Chicken Pox no longer contagious?

Is it when they are scabs? When is it safe for a pregant woman to be around someone who's have Chicken Pox?When are the Chicken Pox no longer contagious?
In hospital, patients with ChickenPox are deem to no longer be infectious (and therefore not require isolation any longer) once their lesion have completely scabbed/crusted over. If they are not completely scabbed, the individual is still infectious.
If the pregnant woman have had ChickenPox, newborn is protected from mom's immunity. If the mom have never had ChickenPox, she should not be around it, again, until completely crusted over.
What's also vital here is the possible exposure prior to developing lesions. ChickenPox is contagious prior to it man evident (i.e., prior to lesion showing on the skin).
Wait til the redness is almsot ALL gone and the scabs are mid-gone. I've hear a few friends who thought that people be done with their chicken pox, but manage to catch them because they were't fully 'un-contageous'.
when they are gone