Examples ofteratogensagents that cause birth defectsare more numerous than you may realize.
Alcohol and smoking are two common teratogens.
It also discusses teratogen exposure and risks and offers prevention tips.
Illustration by Julie Bang for Verywell Health
Illustration by Julie Bang for Verywell Health
What Is a Teratogen?
A teratogen is a substance that may lead to birth defects in an embryo or fetus.
The impact of teratogens on pregnancy or a fetus depends on several factors.
Examples of Teratogens
Teratogens can be grouped into one of several categories.
These include drugs, infections, physical agents, environmental toxins, and maternal health conditions.
Drugs
Many pregnant people take prescription medications and over-the-counter (OTC) medications.
The U.S. Food and Drug Administration (FDA) has a rating system for medication risks during pregnancy.
The FDA’s five risk categories are A, B, C, D, and X.
Category X medications are to be avoided during pregnancy because the risks outweigh the benefits.
The following medications are examples of known teratogens:
Some OTC medications may contain teratogens as well.
One particular teratogen example used in the treatment of leprosy and lupus is thalidomide.
Thalidomide is a category X medication, meaning it poses a substantial risk of birth defects.
The risks can be severe and cause death in the unborn babyeven from one dose.
Don’t take thalidomide if you’re pregnant or think you could be.
Talk to your healthcare provider about alternatives if you are pregnant or are planning to become pregnant.
Another category of teratogens includes alcohol, tobacco, and recreational drugs.
Pregnant people often encounter the common cold and some milder infections without incident.
However, some illnesses have a greater potential to impact a pregnancy.
TORCH is an acronym that can help you remember the most common teratogenic viruses, parasites, and bacteria.
Radiation exposure and heat are both considered physical teratogens.
Radiation, also calledelectric and magnetic fields, is either ionizing or non-ionizing.
Studies have not found that these pose a significant risk during pregnancy.
Ionizing radiation includes things like X-rays, gamma rays, and sunlight.
These can be harmful.
The risk of exposure to ionizing radiation varies, depending on the dose of exposure and pregnancy stage.
The highest risk is associated with higher doses and exposure in the first trimester.
Hyperthermia(abnormally high body temperature) can be teratogenic during pregnancy.
Environmental Toxins
Toxic metals and chemicals can pose risks to a developing fetus.
Lead exposurecan happen from contact with lead in the air, soil, water, and household dust.
Paint used in homes before 1978 often contained lead, and many older water pipes are made of lead.
Maternal Health Conditions
Some maternal health conditions pose teratogenic risks.
PKU is a genetic disorder that is passed down from parents to children.
It is managed through a specialPKU diet.
Talk to your healthcare provider about concerns you have about your health conditions and treatment options.
Controlling health conditions can help to limit the teratogenic risk.
Of course, the impact also depends on the level of exposure.
Some organ systems are susceptible throughout pregnancy, though.
The central nervous system, for example, can be impacted throughout an entire pregnancy.
How Common Are Birth Defects From Teratogens?
The good news is that exposure to teratogens only accounts for a very small percentage of birth defects.
Most of the time, people are able to avoid the things that can negatively impact fetal development.
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