National Institute on Drug Abuse (NIDA) funded researchers have found evidences that link prenatal exposure to tobacco to negative toddler behavior and early smoking experementation (NIDA Notes). An additional study revealed  that prenatal exposure to nicotine causes lasting damage that  makes the brain vulnerable to addiction upon later use of the drug ( Action on Smoking and Health). These data indicate that the children whose mothers smoked during the pregnancy or were exposed to secondhand smoke are more likely to initiate the smoking earlier and became addicted faster than children whose mothers didn't smoke.