Now why is that a problem? Well, that's a problem because the placenta is the organ where nutrient exchange and gas exchange takes place. And if the placenta is damaged, then that fetus cannot actually obtain enough nutrients to develop quickly and efficiently. And that's exactly why smoking is very, very bad for that developing fetus. Now, let's focus on different types of drugs. So we have medicinal drugs, we have recreational drugs and then we also have alcohol.