What are the most sensitive periods for teratogens in 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 something is in the mother’s blood, it can now cross over to the developing fetus. Teratogens are thought to have the ability to affect the fetus about 10 to14 days after conception. During the development of a baby, there are certain organs forming at certain times. If a teratogen has the potential to interfere with the closure of the neural tube, for example, the exposure to the teratogen must occur in the first 3.5 to 4.5 weeks of the pregnancy, since this is when the neural tube is closing. There are some organ systems that 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 s
