nonteratogenic

Nonteratogenic describes substances or exposures that do not induce congenital malformations in a developing fetus when exposure occurs during pregnancy. The term is used in fields such as teratology, pharmacology, toxicology, and obstetrics to indicate a lack of known teratogenic effect under specified conditions. It is a relative label that depends on dose, timing (especially during organogenesis in the first trimester), species studied, and individual susceptibility.

A substance may be nonteratogenic at a certain dose but teratogenic at higher doses, or may appear nonteratogenic in animal studies while showing risk in humans, or vice versa. Nonteratogenic does not imply safety in all respects: it does not guarantee absence of other fetal risks such as growth restriction, functional effects, or later developmental issues. It also does not mean that exposure is recommended during pregnancy.

Assessment of nonteratogenicity relies on animal experiments, clinical observations, epidemiological studies, and postmarketing data. Regulatory agencies historically used categorical pregnancy safety labels, though modern labeling emphasizes specific timing, dosage, and risk statements to support clinical decision-making. Clinicians balance potential benefits against possible risks and may seek safer alternatives or modify dosing when treating pregnant patients.

In practice, “nonteratogenic” is a useful but limited descriptor. It indicates that a substance has not been shown to cause birth defects under defined conditions, but it does not guarantee universal safety across all contexts or doses.