Prenatal Vitamins

Because I'm breastfeeding, I'm still taking prenatal vitamins. I've been on these things forever. Since I found out I was pregnant with Elise-- so, for over 2 years. I swear, they boost my immune system or something. For all of the colds and weird baby diseases that the kids bring home, I barely get sick. Husband gets sick more often than I do, and that was never the case before he knocked me up. Is there any reason not to take prenatal vitamins once you're done breastfeeding? Because I think I'll just keep taking these things until I croak.