Tobacco

(Cigarette Smoking and Birth Weight) "Consistent with previous studies, we found that maternal cigarette smoking was associated with reduced birth weight and an increased risk of LBW,^3-8 shortened gestation and an increased risk of preterm birth,^8,27-29 and intrauterine growth restriction.^3,9,10 Our data indicate that maternal cigarette smoking likely affects infant birth weight via both reduced fetal growth and shortened gestation.

(No Difference Found) Research paid for by the National Institute on Drug Abuse (NIDA) and the Albert Einstein Medical Center in Philadelphia states, "Although numerous animal experiments and some human data show potent effects of cocaine on the central nervous system, we were unable to detect any difference in Performance, Verbal or Full Scale IQ scores between cocaine-exposed and control children at age 4 years."