You might hate me for saying this, but if I go to the gym/for an intense walk/yoga then either I will get a very mild version of the cold (i.e. mild sore throat only) or it will pass through me without symptoms. And I live with a preschooler! Is there a drop-in prenatal yoga class in your area?
I agree with trying herbal or nutritional things (I take a dose of B-Complex), but this has really been the only thing for me that helps me to beat them off. Before this, I was sick every other week with something or another. Bleh.
Also, are you wearing a scarf whenever you go out? I know it's probably superstition or something, but my French and Chinese friends both insist that it can decrease illness. And my chiropractor. Hmm?! So I do that too.
I'm sneezy myself this morning, so I'll be at the gym this afternoon for a light workout (enough to feel hot, a little sweaty). It's that change in weather...yuck.