Higher incidence of genetic defects for their babies. Low birth weight. On average babies born to smokers weigh 8 ounces less than those born to non-smokers. The combination of carbon monoxide poisoning and decreased oxygen levels retard the baby's growth. One study showed that at the age of 14 children of smokers were more likely to have respiratory illness, to be shorter in height and less successful at school.
Smoking is a powerful addiction.
Not everyone can quit at will. Hitting them hard with mortal facts may discourage some of them, but most of those who want to quit need support and encouragement from family and friends.