Definition - What does Embryotoxicity mean?
Embryotoxicity refers to a substance that produces adverse effects in a developing embryo. This occurs when the substance enters the maternal blood stream and is able to cross the placental barrier, entering the blood supply of the embryo. The result of embryotoxicity can be growth retardation, abnormal development of some parts of the body, or embryonic death.
FertilitySmarts explains Embryotoxicity
There are certain chemicals and drugs that may be toxic to a developing embryo. Women who are pregnant or trying to become pregnant should avoid these substances to prevent negative effects in the embryo or miscarriage.
For prescription medications, the drug monograph will provide details about its use in pregnancy. Each country has its own method of classifying drugs. In the United States, the FDA has outlined the following categories:
- Category A - Sufficient number of quality studies show no known risk to a human fetus in the first trimester.
- Category B - Studies in animals show no known risk to an animal fetus. Insufficient studies in human subjects.
- Category C - Animal studies show adverse effects in an animal fetus. Insufficient studies in human subjects. Potential benefit may warrant use in pregnant women despite potential risk to a fetus.
- Category D - Evidence from studies, investigations, or marketing experience shows adverse effects in a human fetus. Potential benefit may warrant use in pregnant women despite potential risk to a fetus.
- Category X - Animal or human studies have demonstrated fetal abnormalities and/or known risk to a human fetus from investigations or marketing experience. Pregnant women should not use this drug as the risk to fetus clearly outweighs potential benefit.