The embryonic period, during which organogenesis takes place, occurs
between implantation at around 14 days to around 60 days postconception
. This is usually the most sensitive period to teratogenesis when exposure to a teratogenic agent has the greatest likelihood of producing a malformation.
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
.
In which period are teratogens the most harmful 1 point?
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. During organogenesis
between days 15 to 60
, teratogenic agents are more likely to cause major congenital malformations.
How early can teratogens affect development?
Exposure to a teratogen can occur through ingestion or environmental exposure during pregnancy. Teratogens can begin affecting the developing embryo as early as
10 to 14 days after conception
. During embryonic development, there are periods when the developing organ systems show more sensitivity to teratogens.
During which specific period of pregnancy will teratogens have their most negative impact?
Most teratogens are harmful only during a critical window of development (e.g., thalidomide is teratogenic only
between days 28 and 50 of pregnancy
). Teratogenic agents inhibit specific receptors or enzymes or disrupt specific developmental pathways (e.g., some agents show neurotropism or cardiotropism).
Is caffeine a teratogen?
In humans,
caffeine does not present any teratogenic risk
. The increased risk of the most common congenital malformations entailed by moderate consumption of caffeine is very slight.
What are long term effects of teratogens?
Teratogens may affect the embryo or fetus in a number of ways, causing
physical malformations
, problems in the behavioral or emotional development of the child, and decreased intellectual quotient (IQ) in the child.
What are 2 common teratogens?
A teratogen is a substance that may lead to birth defects in an embryo or fetus. During pregnancy, exposure to certain chemicals, infections, and drugs may increase the risk that a person will miscarry or that the embryo or fetus could have a developmental abnormality.
Alcohol and smoking
are two common teratogens.
What is the most common teratogen?
Alcohol
: One of the most commonly used teratogens is alcohol, and because half of all pregnancies in the United States are unplanned, it is recommended that women of child-bearing age take great caution against drinking alcohol when not using birth control or when pregnant (CDC, 2005).
Is stress a teratogen?
Maternal psychological stress has essentially been conceptualized as
a teratogen
, that is, an agent that can generate deleterious perinatal and/or developmental outcomes.
What birth defects are caused by teratogens?
During this time, teratogens can cause
neural tube defects such as spina bifida
. Some organs are sensitive to teratogens during the whole pregnancy. This includes the baby’s brain and spinal cord. Alcohol affects the brain and spinal cord, so it can cause harm at any time during pregnancy.
What are the most critical stages for exposure to alcohol as a teratogen?
The critical period for alcohol teratogenicity was confirmed to be
around the time of conception
. Risk for anatomic abnormalities in the offspring was clearly defined among the 5.6% of infants whose mothers drank more than three ounces of absolute alcohol, that is, more than six drinks, per day.
What are teratogens and their effects?
Teratogens are
drugs, chemicals, or even infections that can cause abnormal fetal development
. There are billions of potential teratogens, but only a few agents are proven to have teratogenic effects. These effects can result in a baby being born with a birth defect.
How can teratogens be avoided during pregnancy?
Do not use chemicals that may harm your child
– This includes pesticides, fungicides, rodenticides, or harsh cleaning products. Do not smoke, use drugs or consume alcohol during pregnancy – These teratogens greatly increase the risk of fetal birth defects and other life threatening conditions.
What is the critical period of pregnancy?
In general, major defects of the body and internal organs are more likely to occur
between 3 to 12 embryo / fetal weeks
. This is the same as 5 to 14 gestational weeks (weeks since the first day of your last period). This is also referred to as the first trimester.
What stage of pregnancy do birth defects happen?
Birth defects can occur during any stage of pregnancy. Most birth defects occur in
the first 3 months of pregnancy
, when the organs of the baby are forming. This is a very important stage of development. However, some birth defects occur later in pregnancy.
