Is it dangerous to smoke while pregnant?

Oxygen: Yes. Of course. That is such an obvious answer I am not sure why you would ask. It is dangerous to smoke when not pregnant. Can you imagine wanting a healthy baby but sending it very low levels of oxygen and high levels of carbon monoxide while it is trying to grow? To some of us this seems insane and the opposite of health.

Absolutely yes: Nicotine decreases blood flow to the placenta and also carbon monoxide hurts development of many organs. Stop as soon as possible.