What Is It, Examples, and More

Author: Ashley Mauldin, MSN, APRN, FNP-BC

Editors: Ahaana Singh, Lisa Miklush, PhD, RN, CNS

Illustrator: Jillian Dunbar

What is a teratogen?

A teratogen is something that can cause birth defects or abnormalities in a developing embryo or fetus upon exposure. Teratogens include some medications, recreational drugs, tobacco products, chemicals, alcohol, certain infections, and in some cases, health problems such as uncontrolled diabetes in pregnant people. Exposure to a teratogen can occur through ingestion or environmental exposure during pregnancy. 

Teratogens can begin affecting the developing embryo as early as 10 to 14 days after conception. During embryonic development, there are periods when the developing organ systems show more sensitivity to teratogens. Specifically, if exposure to a teratogen occurs during the first 3.5 to 4.5 weeks of gestation, a neural tube defect, such as spina bifida or anencephaly, may result. 

Various agents have been determined to not cause birth defects and are known as non-teratogenic agents. Examples of non-teratogenic agents that are commonly mistaken for teratogens include spermicides, acetaminophen, and prenatal vitamins.

Is alcohol a teratogen?

Alcohol is a teratogen that can affect the central nervous system of the developing fetus. The central nervous system is sensitive to teratogens for the entire duration of pregnancy, and if alcohol is consumed at any point, there can be severe health problems or birth defects in the baby. It is recommended to avoid consumption of alcohol for the duration of a pregnancy.

Is chickenpox a teratogen?

Chickenpox can have teratogenic effects on a fetus. If a pregnant person develops chickenpox in the first 20 weeks of pregnancy, there is a slight risk of a rare, but serious, birth defect known as congenital varicella syndrome. A fetus with congenital varicella syndrome is at risk of developing skin scars, abnormalities of the eyes, legs, arms, and brain, as well as gastrointestinal problems. If a pregnant person develops chickenpox around the time of delivery, the newborn may be at risk of a life-threatening condition called neonatal varicella, which can result in severe or fatal illness of the newborn within a few days of delivery.

Is BPA a teratogen?

BPA, or bisphenol A, may potentially have teratogenic effects on a developing fetus. BPA is a chemical found mainly in plastic, and is often used in containers that store beverages and food. When exposed to heat, the BPA can leach into food and be ingested. At this time, it is unclear whether BPA has teratogenic effects on the fetus. Recent studies conducted on mice hypothesize that BPA exposure during the last trimester of pregnancy can cause behavioral changes in the newborn after birth. However, no studies have been conducted on human pregnancies. More research is required to clarify the exact relationship of BPA exposure and its effect on the developing fetus. Most health care providers, however, do recommend limiting exposure to BPA during pregnancy.

Is caffeine a teratogen?

Caffeine is not considered to be a teratogen. It is, however, a stimulant and diuretic, which can cause an increase in an individual’s blood pressure and heart rate. If consumed during pregnancy, caffeine can cross the placenta and can have similar effects on the developing fetus’s blood pressure and heart rate. Current recommendations for caffeine consumption during pregnancy suggest limiting daily intake to 200 milligrams. 

What are the most important facts to know about teratogens?

A teratogen is a substance that can cause abnormalities or birth defects in a developing fetus. Common teratogens include some medications, recreational drugs, tobacco products, chemicals, alcohol, certain infections, and in some cases, uncontrolled health problems in the birthing parent. Alcohol is a well-known teratogen that can cause harmful effects on the fetus after exposure at any time during pregnancy. Chickenpox is a teratogen that can potentially cause congenital varicella syndrome or neonatal varicella, depending on the timing of exposure. At this time, there is not enough evidence to determine the exact relationship between BPA exposure and fetal development, but most health care providers recommend limited exposure to BPA during pregnancy. Caffeine is not considered to be a teratogen, but it can have negative effects on the fetus if consumed in large quantities. There are many other potential teratogens, both known and unknown, and if one is uncertain about exposure to them during pregnancy, it is recommended to seek medical counsel. 

Related links

Alcohol use disorder
Anticoagulants: Warfarin
Clinical Reasoning: Routine prenatal care
Fetal alcohol syndrome

Resources for research and reference

Bisphenol A (BPA): Use in Food Contact Application. (2018). In U.S. Food & Drug Administration. Retrieved September 14, 2020, from https://www.fda.gov/food/food-additives-petitions/bisphenol-bpa-use-food-contact-application

Burnett, T. (2019). Chickenpox and pregnancy: What are the concerns? In MayoClinic. Retrieved September 11, 2020, from https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/chickenpox-and-pregnancy/faq-20057886

Caffeine During Pregnancy. (2016). In American Pregnancy Association. Retrieved September 14, 2020, from https://americanpregnancy.org/healthy-pregnancy/pregnancy-health-wellness/caffeine-intake-during-pregnancy-946

Caffeine in pregnancy. (2015). In March of Dimes. Retrieved September 14, 2020, from https://www.marchofdimes.org/pregnancy/caffeine-in-pregnancy.aspx

Kett, J. C. (2013). Perinatal Varicella. Pediatrics in Review, 34(1): 49-51. DOI: 10.1542/pir.34-1-49

Medical Genetics: Teratogens. (n.d.). In Stanford Children’s Health. Retrieved September 11, 2020, from https://www.stanfordchildrens.org/en/topic/default?id=teratogens-overview-90-P09519

Ohtani, N., Suda, K., Tsuji, E., Tanemura, K., Yokota, H., Inoue, H., & Iwano, H. (2018). Late pregnancy is vulnerable period for exposure to BPA. The Journal of Veterinary Medical Science, 80(3): 536–543. DOI: doi.org/10.1292/jvms.17-0460

Teratogens. (n.d.). In Children’s Wisconsin. Retrieved September 11, 2020, from https://childrenswi.org/medical-care/genetics-and-genomics-program/medical-genetics/teratogens