During which Weeks is the fetus most sensitive to teratogens?
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.
What trimester are teratogens most harmful?
Time of exposure: Teratogens are most harmful early in pregnancy, starting about 10 to 14 days after conception to about 8 weeks into pregnancy.
What trimester do teratogens occur?
Exposure and Prevalence About 4% to 5% of birth defects are caused by exposure to a teratogen. 14 The risk of teratogens to a developing fetus is often early in the pregnancy—usually the first trimester and often before implantation. Of course, the impact also depends on the level of exposure.
Which is the most critical period for development in which teratogens affect the fetus?
The embryo is most susceptible to teratogenic agents during periods of rapid differentiation. The stage of development of the embryo determines suscep- tibility to teratogens. The most critical period in the development of an embryo or in the growth of a particular organ is during the time of most rapid cell division.
What is the first 12 weeks of pregnancy called?
The first trimester is the time in between fertilization of the egg by the sperm (conception) and week 12 of a pregnancy. A woman’s body goes through many changes during the first 12 weeks of a pregnancy.
How do teratogens affect a baby in the womb?
As a baby grows in the womb, teratogens may affect parts of the baby’s body as they are forming. For example, the neural tube closes in in the first 3 to 5 weeks of the pregnancy. During this time, teratogens can cause neural tube defects such as spina bifida.
What is the critical period of exposure to teratogens during pregnancy?
The critical period of exposure appears to be from the second to the fifth week of gestation. The most common malformations include craniofacial dysmorphisms, cleft palate, thymic aplasia, and neural tube defects. The tranquilizer thalidomide is one of the most famous and notorious teratogens.
What percentage of birth defects are caused by exposure to teratogens?
About 4-5% of birth defects are caused by exposure to a teratogen during pregnancy Teratogens can impact a baby’s development as little as 10-14 days after conception
What is a teratogen?
Definitions and Statistics “A teratogen is an agent, which can cause a birth defect. It is usually something in the environment that the mother may be exposed to during her pregnancy.