Can a foot massage start labor?

Now that I'm in my 31st week and can no longer comfortably reach my toes,
I'm treating myself to a pedicure tomorrow. I seem to remember reading that
there are parts of the feet and ankles that should not be massaged because
they can bring on labor, but I'm not clear on which parts. In case there's a
little foot massage involved in my pedicure (and lets hope there is, because
I could really use it!), I'd like to be able to enjoy it without wondering
if I'm going to go into labor right then and there. Does anyone know what
areas of the foot/ankle should be avoided (if any)?
Many thanks.
-Melissa