American cheese is a type of processed cheese. It is made with a blend of milk, milk fats and solids, other fats, and whey protein concentrate. As it is a semi-hard, processed cheese, it is safe to eat during pregnancy.
With a high content of protein and calcium, you can choose to ocassionally indulge in American cheese. This is because a diet rich in protein is essential for pregnant women during the second and third trimester of pregnancy, as it is during this time that the baby grows the fastest.
Having said that, American cheese is known to have high fat and sodium content. Too much consumption of saturated fats can lead to heart diseases and high blood pressure. Hence, it is recommended for pregnant women to consult a doctor to permissable quantity of American cheese that they can eat while they are expecting.