What are teratogens? Teratogens are any agent that disrupts a baby's development when a person is exposed to it during pregnancy. Known teratogens include alcohol, smoking, toxic chemicals, radiation viruses, some maternal health conditions and certain prescription drugs. Some teratogen are more concerning than others. How harmful a teratogen is depends on several factors, including the type, amount, duration, and time of exposure as well as genetic influences. Type. Some teratogen, including alcohol and smoking, have a more harmful impact on a developing fetus than others. Amount. The amount of harm to a fetus increases the more the pregnant person consumes or is exposed to a teratogen. Duration of exposure. The longer a fetus is exposed to a teratogen, the more dangerous the effects. Time of exposure. Teratogens are most harmful early in pregnancy, starting about 10 to 14 days after conception to about eight weeks into pregnancy. Genetics. Sometimes the pregnant person's or the baby's unique genetics protect them or make them more vulnerable to certain teratogens. Why they are important. All parents should know what teratogen are and how to avoid them since they can cause harm throughout pregnancy starting around the time of conception. For instance, the risk of miscarriage is higher when you smoke or drink alcohol or exposed to radiation in certain toxic chemicals. These and other teratogens are also linked to premature birth. Additionally, 4% to 5% of birth defects are caused by teratogen. These include physical malformations like spina bifida, cleft palate or microcephaly, when the brain and skull are underdeveloped as well as vision and hearing problems. Teratogens can also affect cognitive development. Babies born to a parent who drinks alcohol or has certain health conditions like thyroid disorders have been shown to have lower IQ scores.