I think Liz is due in December. Maybe they will skate for only the latter part of the tour. Since she's an ice dancer and, therefore, doesn't jump or get tossed into the air, I would imagine that Liz could still be on skates.
I recall that Nancy Kerrigan skated during her pregnancy. I think she was pregnant in her 1st Halloween on Ice which is why she wore a pumpkin outfit. Her doctor said it was ok as long as she didn't jump a lot - so, I think she restricted her self to doubles until she got to 'big' to feel comfortable jumping at all.