I have noticed when studying herbal remedies that A LOT of plants have warnings not to use them if pregnant or nursing.
Lets make a list:
[Note: Some plants should be avoided entirely while others may not be taken in excess. Reasoning for why these plants shouldn't be taken are left to your own research. Common Names are used.]
-Queen Ann's Lace
-Goldenrod
-Lungwort
-Licorice
-Solomon's Seal
-Juniper Berries
-Oregon Grape
-Saw Palmetto