Final answer:
A teratogen is a substance that can impair fetal development, causing birth defects or developmental problems. Alcohol is a well-known teratogen causing fetal alcohol spectrum disorders. Exposure to teratogens is particularly harmful during the fetal sensitive periods of development.
Step-by-step explanation:
The term for any substance, such as a drug, alcohol, or virus, that interferes with fetal development is a teratogen.
These substances can have detrimental effects on the developing embryo or fetus. Alcohol consumption during pregnancy, for example, can lead to fetal alcohol spectrum disorders (FASD), which encompass a range of developmental problems including cognitive and behavioral disorders, and organ and facial malformations.
Exposure to other teratogens such as certain prescription and over-the-counter medications, illegal drugs like heroin and cocaine, viruses such as rubella and HIV, chemical compounds, and environmental toxins can also result in severe birth defects.
The developing fetus is particularly vulnerable during the sensitive periods of development, when certain organs and systems are forming.