Herbs the word itself suggests a plant valued for its medicinal properties. However, it too may have some side effects. Most of the herbal products have not been investigated which authenticate its usage during pregnancy or breastfeeding. Natural sleep remedies that are considered safe during pregnancy are ginseng, honey, nutmeg, and oats. The most unsafe herbs, which you should avoid during pregnancy or nursing, are as follows: 1. American hellebore 2. kava kava 3. marijuana 4. melatonin 5. mugwort 6. passion flower 7. Petasites 8. Rauwolfia 9. Siberian ginseng 10. taumelloolch 11. tulip tree 12.