Teratogeni

Teratogeni, or teratogens, are agents capable of causing birth defects or other developmental problems in a fetus when exposure occurs during pregnancy. They can be chemical substances, medications, infectious agents, radiation, or other environmental factors. The risk and type of defect depend on the specific agent, the dose, and the timing of exposure, with the first trimester and key periods of organ formation being particularly sensitive.

Common drug and chemical teratogens include certain anticonvulsants (for example, valproic acid), isotretinoin, methotrexate, thalidomide, and alcohol. Tobacco smoke and some other substances can also have teratogenic effects. Infections such as rubella, cytomegalovirus, toxoplasmosis, varicella, and syphilis are infectious teratogens that can cause congenital anomalies or developmental problems. Physical factors like ionizing radiation and, in some cases, environmental pollutants or high-dose radiation exposure are also teratogenic. Maternal health conditions, including poorly controlled diabetes, can increase the risk of birth defects and developmental issues.

The mechanisms by which teratogens affect development include disruption of cell proliferation, differentiation, migration, and programmed cell death, as well as epigenetic changes. The outcome may range from structural malformations to growth restriction or later neurodevelopmental disorders. Timing is crucial; exposure during critical windows can have different consequences than exposure later in gestation.

Prevention focuses on avoiding known teratogens during pregnancy, consulting health professionals about medication use before and during pregnancy, and preventive measures such as vaccination and folate supplementation to reduce risk of certain defects. Prenatal screening and ultrasound help detect anomalies early.