Now, the problem with that is, remember, the placenta is the organ that basically exchanges nutrients and gas products between the fetal blood and that placenta and that mother's blood. The problem with these carcinogens is they can easily cross across that placental membrane. And so all those carcinogens that end up in the blood can also end up within that developing fetus. And these carcinogens can cause different types of developmental problems. Now, what else do we have in cigarettes? Well, we also have nicotine.