Well just think about it and look at what chemicals are contained in cigarettes alone
Chemical (Found in): Carbon monoxide (car exhaust), Nicotine (bug sprays), Tar (material to make roads), Arsenic (rat poison), Ammonia (cleaning products), Hydrogen cyanide (gas chamber poison), Cyanide (deadly poison), Acetone (nail polish remover), Butane (cigarette lighter fluid), DDT (insecticides), Formaldehyde (to preserve dead bodies), Sulphuric acid (car batteries), Cadmium (used to recharge batteries), Freon (damages earth's ozone layer), Geranic acid (a fragrance), Methoprene (a pesticide), Maltitol (a sweetener not permitted in foods)
While none of those chemicals is good for your baby, two compounds, nicotine and carbon monoxide are especially harmful. These two toxins account for almost every smoking-related complication in pregnancy.
The most serious complications including stillbirth, premature delivery, and low birth weight. What happen is the red blood cells that carry oxygen start to pick up molecules of carbon monoxide instead and caused reduction your baby's supply of oxygen.
I personally think if you really care about the safety of your baby you can get a quick glance at Quitting Smoking While Pregnant as a source of reference.
