Compounds with teratogenic effects can cause genetic defects during pregnancy and subsequently lead to unwanted abortions. Unwanted abortions and postnatal genetic defects can impose economic and psychological burden on the community. This systematic review was conducted to report medicinal plants with teratogenic and abortion-inducing side effects that are used in Iran. To conduct this systematic review, all articles specifically on the teratogenic and abortion-inducing effects of Iranian medicinal plants were retrieved from the Institute for Scientific Information (ISI) and PubMed and their findings evaluated. Many plants have been reported to display teratogenic and abortion-inducing effects, but a limited number of them were experimentally examined and demonstrated to have such effects. Certain plants such as Perovskia abrotanoides and Lawsonia inermis can simultaneously exert teratogenic and abortion-inducing effects. Plants and their derivatives can cause teratogenic effects and lead to unwanted abortion through several action mechanisms. Such plants cannot be considered harmless solely because they are natural; therefore, they should be used during pregnancy cautiously, under physician's supervision, and at specific doses.