Potential developmental effects of licit and illicit substances in humans: An approach to risk-specific dose and incidence.

Teratogens encompass any agent capable of causing a birth defect or elevating the incidence of defects within the population. This category includes substances like drugs, both legal and illegal. These substances cause congenital anomalies depending on the stage of development at the time of exposure, the dose, and the exposure time associated with the embryo.