Teratogenicity refers to the ability of certain substances or factors to cause developmental abnormalities in a fetus during pregnancy. These abnormalities can affect physical structure, function, or growth, leading to conditions such as birth defects. Common teratogens include certain medications, alcohol, and infections. The effects of teratogenicity depend on various factors, including the timing of exposure, the dose, and the genetic susceptibility of the fetus. Understanding teratogenicity is crucial for expectant mothers, as it helps them make informed choices about medications and lifestyle factors that could impact fetal development.