In plain words
A teratogen is any agent that can cause a birth defect or harm to a developing embryo or fetus. Teratogens include some medicines, certain infections, alcohol, some chemicals, and radiation. Risk depends on the agent, the amount, the timing, and the person. Some exposures matter most in the first weeks, when many organs form, often before a pregnancy is known. Being a teratogen does not mean harm will happen. Most exposures are safe, and some medicines have been studied well enough that their risk is known. Many people ask a provider about a specific exposure before or early in pregnancy. Not every exposure is known, and that uncertainty is part of why preconception planning exists.
The deeper version
A teratogen is an exogenous agent that, when exposure occurs during embryonic or fetal development, raises the incidence of structural or functional malformation above background. Critical periods differ by organ system, and the first trimester is most sensitive for structural defects. Known teratogen classes include certain anticonvulsants, retinoids, warfarin, alcohol, and some infections. Labeling moved from FDA letter categories to narrative risk summaries under the Pregnancy and Lactation Labeling Rule (2015).
Where it comes up
- The preconception visitBefore Pregnancy
- Supplements beyond the prenatal: what's worth asking aboutPregnancy: Eating
- Trimester Zero: preparing your body before pregnancyBefore Pregnancy
What mothers here say about teratogen
No one has posted under this term yet.
Sources
- U.S. Food and Drug Administration — Pregnancy and Lactation Labeling Rule, final rule, 2014 (effective 2015)
- Organization of Teratology Information Specialists — OTIS fact sheets on exposures in pregnancy