It is often stated that boric acid has the same toxicity as ordinary table salt in humans, which can be a little misleading. To understand what this means, it is important to understand a little bit about toxicology. In the medical field an objects toxicity is usually described as an LD50 value.
Mozzarella is the main type of cheese that is used on most pizzas. There are many different kinds of Mozzarella. Try to find a store that carries whole milk mozzarella. This is a nice creamy flavored mozzarella. It makes an excellent pizza.
Pizzas are often topped with mozzarella, which is fine to eat during pregnancy. But you'll have to steer clear of pizzas topped with soft mould-ripened cheese, such as brie and camembert, and blue-vein cheese, such as danish blue and stilton. These cheeses contain more Listeria bacteria than other cheeses.