Teratogens are substances or environmental factors that can cause birth defects when pregnant people are exposed to them. Teratogens have a wide variety of effects on the unborn child as well as on the development of children after birth and on adolescents. Let's look at this in more detail.
Teratogens can take the form of everything from alcohol and tobacco to certain drugs (prescription or otherwise) to pollutants to viruses. Any of these substances or factors can change the course of an unborn child's development and cause a number of physical and mental defects. Alcohol, for instance, affects the unborn child's central nervous system, and this can lead to fetal alcohol syndrome, which manifests in everything from heart defects to learning disabilities to facial deformities.
Children and adolescents who have been exposed to various teratogens before birth often struggle with physical, mental, and emotional disorders. Some develop extremely serious conditions like spina bifida. Others develop ADHD or learning disabilities. Still others can show cleft palate, thyroid troubles, hearing loss, blindness, and neurological issues.