The teratogenic effect is thought to be the effect of an agent that is able to cross the pair and may cause serious damages to the fetal or embryo development and will lead to abnormalities in the fetus or newborn. Each pregnant woman may have a condition that can be contracted in or during pregnancy. Some of these maternal diseases or medications which are used to treat these diseases may have teratogenic effects on the fetus and impair the development of the fetus. According to previews studies, control of maternal diseases before and during pregnancy is necessary. Regarding to the harmful effects of teratogenic factors on the fetus, in this review we studied some teratogenes such as radiations, infection agents, maternal conditions, teratogenic medications etc.