Final answer:
Thalidomide is a teratogen that can cause deformities during fetal development. It's critical to avoid exposure during pregnancy, especially during the first trimester when major organ formation occurs. Thalidomide can cause limb defects and other birth defects.
Step-by-step explanation:
Thalidomide is a teratogen, which is a substance that can cause deformities during fetal development. Its chemical structure allows it to exist in two forms, or enantiomers, which can have different effects. Thalidomide was originally marketed as a sedative, but it was discovered to cause limb defects in babies born to women who took the drug during pregnancy. The critical periods for Thalidomide exposure are during embryogenesis and fetal development, when the fetus is most vulnerable to its effects.
During pregnancy, there are different stages of fetal development, known as trimesters. The first trimester is a critical period because this is when the major organs and structures are formed. Exposure to teratogens during this time can lead to severe birth defects. The second and third trimesters are also important for fetal growth and development, but the risks of teratogen exposure may be reduced compared to the first trimester.
The effects of Thalidomide during these critical periods include limb defects, such as shortened or missing limbs. Other birth defects can also occur, affecting various organ systems. It's important for pregnant women to avoid exposure to teratogens like Thalidomide to minimize the risk of birth defects.