Recognition of human teratogens offers the opportunity to prevent exposure at critical periods of development and prevent certain types of congenital malformations in general, drugs, food addi. There are broadly 3 periods identified in fetal development 6 list proved human teratogens table 2 in chapter 8 is a selected list of some known human teratogens and their clinical effects. 1 hazards to prenatal development: teratogens •teratogens are any agents from the environment that can cause harm to the developing fetus •many harmful agents cause damage only if exposure occurs during a sensitive period of prenatal.
In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect this is called her background risk this fact sheet talks about the critical periods of development and types of birth defects that can result from exposures at different stages of pregnancy. Teratogens are especially damaging in the embryonic stage because it is a critical period in prenatal development later, during the fetal stage, the environment provided by the mother affects the baby’s size, behaviour, intelligence and health, rather than the formation of organs and limbs (bernstein and nash, 1999, p 333. Caption chart shows time when teratogens are most effective at disrupting prenatal development the red bars denote the most sensitive periods, when major defects can be produced (eg, amelia, absence of limbs) the yellow bars indicate stages that are less sensitive to teratogens, when minor. Teratology and drugs in pregnancy: jennifer r niebyl, epidemiological pitfalls in assessing human teratogens are myriad, and several different surveillance methods are used withdrawal should be watched for carefully in the neonatal period marijuana no teratogenic effect of marijuana has been documented.
Critical periods of human development (sensitivity to teratogens) prev table of content next but it does have an effect on fetal growth, resulting in increased premature delivery, thus, lower weight infants critical periods of human development (sensitivity to teratogens. The teratogens have potential to affect the normal development of human embryo following maternal exposure to them these agents are usually environmental factors such as drugs, chemicals, radiation, maternal diseases and viruses. Teratogens are harmful environmental influences to fetal development (berk, 2008) these external interferences can come from a variety of sources stress of the mother is considered a teratogen and results in behavioral problems, low birth weight, emotional and behavioral problems (department.
Prenatal development development happens quickly during the prenatal period, which is the time between conception and birththis period is generally divided into three stages: the germinal stage, the embryonic stage, and the fetal stage. Alcohol use in pregnancy has significant effects on the fetus and the baby alcohol can pass from the mother’s blood stream through the placenta to the fetus since alcohol is broken down more slowly in a fetus than in an adult, alcohol levels tend to remain high and stay in the baby’s body longer. Prenatal diagnosis prenatal diagnosis are the clinical tools used to determine both normal and abnormal development there are a growing number of new diagnostic techniques that are being applied to human embryonic development.
Learning objectives review the stages of prenatal development explain how the developing embryo and fetus may be harmed by the presence of teratogens and describe what a mother can do to reduce her risk. Ionizing radiation has serious adverse developmental effects related to the period of gestation at exposure 44 the period in human development most sensitive to this teratogen is 18–36 days postconception the most frequent malformations are microcephaly and neural tube defects. Prenatal development is the process that occurs during the 40 weeks prior to the birth of a child there are three stages of prenatal development: germinal, embryonic, and fetalprenatal development is also organized into three equal trimesters, which do not correspond with the three stages.
Appendix a teratogens/prenatal substance abuse 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. The period of the embryo is the most dangerous one when it comes to teratogens, or environmental agents that can damage the embryo from the moment the embryo implants and connects itself with mother’s blood stream it becomes vulnerable to teratogens. It just goes to show that teratogens are real, and they can harm a woman’s baby during the many critical periods of their prenatal development smoking is not the only teratogen to be aware of there are many others, such as alcohol, caffeine, cocaine, methamphetamine (meth), and marijuana. When it comes to development, timing is everything • the embryonic period (3rd to 8th weeks) is the most sensitive time for causing structural birth defects • the fetal period (9th week to birth) is not very sensitive to teratogen induced birth defects, although some organs remain at risk, especially the.
Teratogens child development 1 category prenatal screening, part 12 - teratogens and their effects on the developing brain and mindavi - duration: 12:21. Chapter 2 genetics and prenatal development instructor: monica moreno tuesday evening class: 6:50 pm to 10:00 pm • lo 25 explain how the theory of genotype → environment effects casts centered in the embryonic period lo 213 teratogens. Alcohol use, at any time during the pregnancy, has the potential to cause birth defects and health problems in a baby, since the central nervous system is sensitive to teratogens the entire nine months of gestation.