Folate: Folate or Folic Acid can help prevent neural tube defects in the fetus. Folate can be consumed by adding dark green, leafy vegetables like spinach to the diet. All prenatal vitamins will include folate.
DHA: The perfect source for DHA is fatty fish. For the vegetarian this is out of the question. DHA supplements created from algae can be found for the vegetarian.
Iodine: All humans need iodine to live. If the majority of the foods consumed are salt free or natural, adding just 3/4 of a teaspoon to the food over the course of the day will up that iodine level to healthy.