Treasury regulations (26 C.F.R.)--commonly referred to as Federal tax regulations-- pick up where the Internal Revenue Code (IRC) leaves off by providing the official interpretation of the IRC by the U.S. Department of the Treasury.
No. Pregnant women are not eligible to donate blood according to the American Red Cross, which also advises waiting at least six weeks after giving birth. Although the amount of blood in your body increases by about 50 percent during pregnancy, you and your growing baby need it for optimum health and nutrition.
Also, I don't know how donating plasma works to be honest, but you might want to get your iron levels checked just in case. I always end up anemic while pregnant. I can't imagine what would happen if i donated blood on top of that. :) I doubt there would be any long term affects from donating blood though to the baby.