What is a teratogen?

A teratogen is an agent, which can cause a birth defect. A teratogen is usually something in the environment that the mother may be exposed to during her pregnancy.

It could be a prescribed medication, a street drug, alcohol use or a disease present in the mother, which could increase the chance for the baby to be born with a birth defect.

What are the most sensitive periods for teratogens during pregnancy?

Once the egg is fertilized (conception), it takes about six to nine days for implantation (anchoring into the uterus) to occur. Once the fertilized egg is connected to the uterus, a common blood supply exists between the mother and the embryo.

In other words, if a teratogen is in the mother's blood, it can now enter the developing fetus. Teratogens are thought to have the ability to affect the fetus about 10 to 14 days after conception.

During the a baby's development, certain organs form at certain times. If a teratogen has the potential to interfere with the closure of the neural tube. The exposure to the teratogen must occur during the first 3.5 to 4.5 weeks of the pregnancy because the neural tube is closing.

Some organ systems are sensitive to teratogens throughout the entire pregnancy, such as the central nervous system. The central nervous system is the baby's brain and spine.

One teratogen that affects the central nervous system is alcohol. Alcohol, at any time during the pregnancy, has the potential to cause birth defects and health problems for the baby, because the central nervous system is sensitive to teratogens. This is why alcohol consumption should be avoided during pregnancy.