What kind of cleaning sipplies are dangerous when you are pregnant?

Many. The problem is, many cleaning supplies contain substances that are not good for you, pregnant or not. You may do well to stick with "green" cleaners, before, during, and after your pregnancy. Many of these household products are made from things like lemon juice and white vinegar, and are safe for almost anyone, regardless of pregnancy.
No changes needed. The household cleaning supplies that are safe before pregnancy are also safe during pregnancy. However, a pregnant woman should watch her balance, as she can slip and fall more easily (looking at it that way, a wet slippery floor would be dangerous). Odors and fumes from cleaners such as ammonia or clr can seem much stronger and more irritating to a pregnant woman's senses.