teratogene

Teratogene, or teratogen, refers to any agent that can disturb the development of an embryo or fetus, leading to congenital anomalies, growth problems, or neurodevelopmental disorders. Teratogens can be chemical, physical, infectious, or environmental, and their effects depend on dose, timing during pregnancy, duration of exposure, and the genetic susceptibility of the fetus.

Common examples include certain medications (such as isotretinoin, valproic acid, methotrexate, and historic cases like diethylstilbestrol), alcohol, tobacco smoke, infectious agents (rubella, cytomegalovirus, toxoplasma), ionizing radiation, and various environmental chemicals or heavy metals. The thalidomide tragedy in the late 1950s and early 1960s underscored the severe risks of teratogens and led to stricter drug testing and labeling. Fetal alcohol spectrum disorders illustrate the impact of prenatal alcohol exposure. Maternal conditions such as uncontrolled diabetes can also increase teratogenic risk.

Mechanisms by which teratogens act are diverse, including disruption of cell signaling, DNA damage, oxidative stress, interference with folate pathways, and direct cytotoxic effects. The most critical period is organogenesis, roughly the first trimester, when many organs form; exposures later in pregnancy tend to affect growth, function, or neurodevelopment rather than gross anatomy.

Public health responses emphasize careful preconception planning, risk communication, use of safer alternatives during pregnancy, and regulatory measures to limit exposure. Ongoing research aims to refine exposure guidelines and understand gene–environment interactions that influence teratogenic risk.