Pregnancy 101: Where to pregnancy cravings come from? And if the craving is for something safely edible (not like dirt or crayons) is it ok to just go ahead and eat whatever it is you're craving?

Forget pickles and ice cream. Pregnancy cravings go way past these stereotypical desires of pregnant mamas. But where do our needs for these desires come from and are they ok to indulge in?

Dr. Siobahn Dolan, mother of three, OB/GYN and March of Dimes Consultant to the Office of the Medical Director, says "I don’t think anyone really knows what causes cravings. But as long as you don’t eat dirt or other inedible items, it is fine to eat what you’re craving."

Dr Dolan adds, "Just watch out for eating too much of certain things -- you don’t want to eat too much tuna (contains mercury) or too many caffeinated items (including coffee, tea, diet sodas and chocolate)."