By What causes teratogenesis?
A teratogen is any agent that causes an abnormality following fetal exposure during pregnancy. Teratogens are usually discovered after an increased prevalence of a particular birth defect. For example, in the early 1960’s, a drug known as thalidomide was used to treat morning sickness.
Why do teratogens cause birth defects?
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 the first 3 to 5 weeks of the pregnancy. During this time, teratogens can cause neural tube defects such as spina bifida.
Is smoking a teratogen?
A teratogen is any agent that disrupts a baby’s development when a person is exposed to it during pregnancy. Known teratogens include alcohol, smoking, toxic chemicals, radiation, viruses, some maternal health conditions, and certain prescription drugs.
What stage 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.
Is crying during pregnancy bad?
Pregnancy can make you an emotional wreck, but you’re not alone. Rest assured that crying spells are perfectly normal, and this part of pregnancy probably isn’t anything to worry about.
What happens to baby when mom is stressed?
Most recently, some studies are suggesting that stress in the womb can affect a baby’s temperament and neurobehavioral development. Infants whose mothers experienced high levels of stress while pregnant, particularly in the first trimester, show signs of more depression and irritability.
What are the effects of a teratogenic agent?
Teratogenic agents inhibit specific receptors or enzymes or disrupt specific developmental pathways (e.g., some agents show neurotropism or cardiotropism). Effects of teratogens are dose-dependent.
What can a teratogen do to a fetus?
A teratogen is an environmental agent that can cause abnormalities in an exposed fetus. The effects depend on the nature of the teratogen, the timing at which the exposure occurs and, most likely, the genetic susceptibility of the mother and/or the fetus.
When does a teratogenic agent kill an embryo?
During the first two weeks of gestation, teratogenic agents usually kill the embryo rather than cause congenital malformations. Major malformations are more common in early embryos than in newborns; however, most severely affected embryos are spontaneously aborted during the first six to eight weeks of gestation.
When is the critical period of exposure to teratogens?
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.