Benzodiazepines may not be safe to be taken during pregnancy. They are not teratogens, which cause birth defects, but they may cause cleft palate in a small number of babies. Benzodiazepines can be taken in overdoses and can cause dangerous deep unconsciousness. However, they are much less toxic than the drugs they replaced, the barbiturates. Death rarely results when a benzodiazepine is the only drug taken. When combined with other central nervous system depressants such as alcohol and opiates, the potential for toxicity increases. Benzodiazepines are commonly misused and taken in combination with other drugs of abuse.