Items that appear better to avoid during pregnancy: aspartame, animal products due to industrial carcinogens and flame retardants building up in animal fat (see videos here, here), fish due to mercury contamination (see videos here, here, here, here, here) and domoic acid, alcohol, lamb due to toxoplasma parasites, chicken due to phthalates, meat (see also here, here), licorice, a vegan diet lacking vitamin B12 (see videos here, here, here) and iodine, avocados, chamomile tea, and flax seeds (during the last 2 trimesters of pregnancy). Also, pregnant women may want to ignore health food store advice and during the summer in certain states avoid tap water due to the chlorine levels. Homeopathy appears useless for the induction of labor. Iron supplements (see also here) should probably only be taken in the context of iron deficiency anemia. Folic acid supplements should be taken during early pregnancy, but there is controversy as to whether they may do more harm than good in other circumstances. Items that are safe to consume during pregnancy: peanuts, and caffeine under a certain level (see also here).
See also the related blog post: Mercury Testing Recommended Before Pregnancy.
To help out on the site, please consider volunteering.