First of all, you should discard your potatoes if they turn green, damaged or rotten. Green potatoes contains toxin which is very harmful to the development of the fetus.
Potatoes are rich in nutrients.
Potatoes contain flavonoids which helps to keep blood pressure down. High blood pressure during pregnancy can cause many complications.
It is also rich in folic acid which can help to prevent birth defect in newborn.
Furthermore, potato is rich in iron, calcium and potassium which are good for the development of fetus.