These are all caused by actions other than the ingestion of drugs, such as the use of drugs while pregnant or driving. One can, and usually does, use drugs when neither pregnant nor driving. It is worth noting that the use of cocaine has not been definitively linked to birth defects or mental retardation, but the use of nicotine has as has the use of alcohol. Marijuana has also not been definitively linked to birth defects or mental retardation, nor to substantially increased risks of traffic accidents. ref1, ref2.