Final answer:
Substances that can cause birth defects are referred to as teratogens, which include alcohol, cigarette smoke, and certain drugs and pathogens. The impact of a teratogen on fetal development is influenced by its potency, dose, duration, and timing of exposure.
Step-by-step explanation:
Birth Defects: Teratogens
Substances that can cause birth defects are commonly referred to as teratogens. A teratogen is any environmental agent—biological, chemical, or physical—that causes damage to a developing embryo or fetus. The degree of teratogenicity, or the harm that a teratogen can cause, depends on several factors, including the potency of the teratogen, the susceptibility of the fetus, the dose and duration of exposure, and the timing of the exposure during development.
Examples of teratogens include alcohol, cigarette smoke, various prescription drugs, and certain pathogens, such as viruses like HIV and rubella. Alcohol, for instance, is a well-known teratogen that may result in fetal alcohol spectrum disorders (FASD), which can cause a range of lifelong cognitive and physical impairments.