What is a teratogen?
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.
What is the most common teratogen used in pregnancy?
Tobacco: Another widely used teratogen is tobacco. According to Tong et al. (2013) in conjunction with the Centers for Disease Control and Prevention, data from 27 sites in 2010 representing 52% of live births, showed that among women with recent live births: About 23% reported smoking in the 3 months prior to pregnancy.
How long does it take for a teratogen to affect development?
If a teratogen has the ability to affect the development of the neural tube, the exposure would need to occur before the time the neural tube closes, which is around three to four weeks. Some organ systems are susceptible throughout pregnancy, though.
What are the risk factors for teratogen-induced birth defects?
Being male or female: Males are more likely to experience damage due to teratogens than are females. It is believed that the Y chromosome, which contains fewer genes than the X, may have an impact. Figure 2.9 illustrates the timing of teratogen exposure and the types of structural defects that can occur during the prenatal period.
What teratogen is linked to low birth weight?
In addition, almost 3 percent of pregnant women use illicit drugs such as marijuana, cocaine, Ecstasy and other amphetamines, and heroin. These drugs can cause low birth-weight, withdrawal symptoms, birth defects, or learning or behavioral problems.
Which teratogen is the leading cause of developmental disabilities?
Exposure to alcohol in utero is the most common teratogenic cause of developmental disabilities, including microcephaly, cognitive disability, learning disabilities, ADHD and behavioural challenges. Fetal Alcohol Spectrum Disorder (FASD) occurs worldwide in approximately 1.9 per 1000 live births.
What are the 4 types of teratogens?
Additionally, teratogens may also affect pregnancies and cause complications such as preterm labors, spontaneous abortions, or miscarriages. Teratogens are classified into four types: physical agents, metabolic conditions, infection, and finally, drugs and chemicals.
Which teratogen is currently a leading cause of birth defects and mental retardation?
Isotretinoin is a molecule and a byproduct (metabolite) of vitamin A, and in greater than normal amounts in pregnant women, it can cause fetal abnormalities including cleft lips, ear and eye defects, and mental retardation.
What are 5 types of teratogens?
Teratogenic agents include infectious agents (rubella, cytomegalovirus, varicella, herpes simplex, toxoplasma, syphilis, etc.); physical agents (ionizing agents, hyperthermia); maternal health factors (diabetes, maternal PKU); environmental chemicals (organic mercury compounds, polychlorinated biphenyl or PCB, ...
What are 2 common teratogens?
Common teratogens include some medications, recreational drugs, tobacco products, chemicals, alcohol, certain infections, and in some cases, uncontrolled health problems in the birthing parent. Alcohol is a well-known teratogen that can cause harmful effects on the fetus after exposure at any time during pregnancy.
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 common teratogens quizlet?
Terms in this set (11)Cocaine. ... Alcohol. ... Nicotine. ... Mercury. Mental retardation, blindness.Syphilis. Mental retardation, deafness, meningitis.Caffeine. Miscarriage, low birth weight.Radiation. Higher incidence of cancers, physical deformities.High water temperatures. Increased chance of Neural tube defects.More items...
During which stage of fetal development is exposure to teratogens most damaging quizlet?
- The effects of a teratogenic agent are worst during the critical period when an organ system grows most rapidly. - Organogenesis takes place during the embryonic period (weeks 3-8 of prenatal development).
What is teratogenic effects in pregnancy?
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.
Which teratogen can cause spina bifida?
Polychlorinated biphenyls, also known as PCBs, are shown to cause fetal growth restriction and skin discolouration. X-rays can cause problems with fetal development, such as spina bifida, cleft palate, blindness, abnormalities of the arms and legs, or microcephaly, which is a condition where the brain is too small.
When are teratogens most harmful during pregnancy?
Time of exposure: Teratogens are most harmful early in pregnancy, starting about 10 to 14 days after conception to about 8 weeks into pregnancy. Genetics: Sometimes, the pregnant person's or the baby's unique genetics protect them or make them more vulnerable to certain teratogens.
What are the most common teratogens quizlet?
Terms in this set (11)Cocaine. ... Alcohol. ... Nicotine. ... Mercury. Mental retardation, blindness.Syphilis. Mental retardation, deafness, meningitis.Caffeine. Miscarriage, low birth weight.Radiation. Higher incidence of cancers, physical deformities.High water temperatures. Increased chance of Neural tube defects.More items...
During which stage of fetal development is exposure to teratogens most damaging quizlet?
- The effects of a teratogenic agent are worst during the critical period when an organ system grows most rapidly. - Organogenesis takes place during the embryonic period (weeks 3-8 of prenatal development).
When are teratogens most harmful during pregnancy?
Time of exposure: Teratogens are most harmful early in pregnancy, starting about 10 to 14 days after conception to about 8 weeks into pregnancy. Genetics: Sometimes, the pregnant person's or the baby's unique genetics protect them or make them more vulnerable to certain teratogens.
What are the effects of teratogens on prenatal development?
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.
Question
Which teratogen is connected with low birth weight and slowed neurological development?
Toxic During Pregnancy
A teratogen is a substance that can negatively affect the outcome of a pregnancy due to its toxicity to the developing embryo or fetus. There are many different types of teratogens, which can range from infectious agents to various drugs and chemicals.
What is the role of genetics in teratogenic effects?
Genetics: Genetic make-up also plays a role on the impact a particular teratogen might have on the child. This is suggested by fraternal twins exposed to the same prenatal environment, but they do not experience the same teratogenic effects. The genetic make- up of the mother can also have an effect; some mothers may be more resistant to teratogenic effects than others.
Which chromosome contains fewer genes than the X?
Being male or female: Males are more likely to experience damage due to teratogens than are females. It is believed that the Y chromosome, which contains fewer genes than the X, may have an impact.
What is anoxia in babies?
Anoxia is a temporary lack of oxygen to the brain. Difficulty during delivery may lead to anoxia which can result in brain damage or in severe cases, death. Babies who suffer both low birth weight and anoxia are more likely to suffer learning disabilities later in life as well.
Can a low birth weight cause a preterm birth?
A child might also have a low birth weight if it is born at less than 37 weeks gestation (which qualifies it as a preterm baby). Early birth can be triggered by anything that disrupts the mother’s system. For instance, vaginal infections or gum disease can actually lead to premature birth because such infection causes the mother to release anti-inflammatory chemicals which, in turn, can trigger contractions. Smoking and the use of other teratogens can lead to preterm birth.
What is teratogen in pregnancy?
Table of Contents. Types. Exposure and Prevalence. Prevention. 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.
How do teratogens affect pregnancy?
The impact of teratogens on pregnancy or a fetus depends on several factors. The timing and length of exposure, the stage of pregnancy when the exposure happened, whether a parent’s genes make them more susceptible, and the type of agent they were exposed to all contribute to the risk.
When to avoid teratogens during pregnancy?
It is important to avoid teratogens throughout your pregnancy, but the highest risk to a fetus is in the first trimester.
What is the chance of giving birth to an infant with eye cataracts, heart malformations, or deaf?
6 chance of giving birth to an infant with eye cataracts, heart malformations, or deafness.
What is a VSD in newborns?
A newborn is evaluated for a heart murmur and found to have a ventricular septal defect (VSD). The history is notable for lack of prenatal care. Near delivery, an ultrasound evaluation showed intrauterine growth retardation.
What causes amputations in the uterus?
Reduced quantity of amniotic fluid and other mechanical forces can cause malformations and even intrauterine amputations.
How do monozygotic twins occur?
Monozygotic and Dizygotic Twins. Monozygotic twins occur when a single zygote or fertilized egg split apart in the first two weeks of development. The result is the creation of two separate but genetically identical offspring. About one-third of twins are monozygotic twins (identical twins).
What is the cause of Klinefelter syndrome?
Klinefelter Syndrome is caused when an extra X chromosome is present in the cells of a male due to a random event. The Y chromosome stimulates the growth of male genitalia, but the extra X chromosome inhibits this development. The male can have some breast development, infertility, and low levels of testosterone.
How does Tay Sachs disease happen?
1 in 10,000. Tay Sachs Disease is caused by enzyme deficiency resulting in the accumulation of lipids in the nerve cells of the brain. This accumulation results in progressive damage to the cells and a decrease in cognitive and physical development. Death typically occurs by age 5.
What is the most common cause of chromosomal abnormalities?
A chromosomal abnormality occurs when a child inherits too many or too few chromosomes. The most common cause of chromosomal abnormalities is the age of the mother. A 20-year-old woman has a 1 in 800 chance of having a child with a common chromosomal abnormality. A woman of 44, however, has a one in 16 chance.
How many births are there at 35?
1 in 300 births at age 35. Trisomy 13 is caused by an extra chromosome 13. Affected individuals have multiple congenital disabilities and early death. 1 in 7,906. Trisomy 18 is caused by an extra chromosome 18, and the affected individual also has multiple congenital disabilities and early death. 1 in 3,762.
What are some examples of polygenic inhereitance?
Some features follow the additive pattern which means that many different genes contribute to an outcome. Height, weight, skin tone, and intelligene are examples of polygenic inhereitance. Take for example, skin, where an individual would have a combination of 3 gene pairs (e.g., AABBCC).
What are the traits of a dominant gene?
Geneticists refer to different versions of a gene as alleles. Some dominant traits include having facial dimples, normal vision, and dark hair. Some recessive traits include red hair and being nearsighted. Sometimes the dominant gene does not entirely suppress the recessive gene; this is called incomplete dominance.
What is the name of the embryo that is about nine weeks old?
When the organism is about nine weeks old, the embryo is called a fetus . At this stage, the fetus is about the size of a kidney bean and begins to take on the recognizable form of a human being as the “tail” begins to disappear.
What are the three periods of prenatal development?
Let’s take a look at some of the changes that take place during each of the three periods of prenatal development: the germinal period, the embryonic period, and the fetal period.
How long is a fetus?
At about 16 weeks, the fetus is approximately 4.5 inches long. Fingers and toes are fully developed, and fingerprints are visible. During the 4-6th months, the eyes become more sensitive to light and hearing develops. The respiratory system continues to develop. Reflexes such as sucking, swallowing and hiccuping develop during the 5th month. Cycles of sleep and wakefulness are present at that time as well. Throughout the fetal stage, the brain continues to grow and develop, nearly doubling in size from weeks 16 to 28. The majority of the neurons in the brain have developed by 24 weeks although they are still rudimentary and the glial or nurse cells that support neurons continue to grow. At 24 weeks the fetus can feel pain (Royal College of Obstetricians and Gynecologists, 1997).
How many cells are in a zygote?
During the first week after conception, the zygote divides and multiplies, going from a one-cell structure to two cells, then four cells, then eight cells, and so on. The process of cell division is called mitosis . After the fourth division, differentiation of the cells begins to occur as well. Differentiated cells become more specialized, forming different organs and body parts. After 5 days of mitosis, there are 100 cells, and after 9 months there are billions of cells. Mitosis is a fragile process, and fewer than one-half of all zygotes survive beyond the first two weeks (Hall, 2004).
What happens during the embryonic stage?
During the embryonic stage, the heart begins to beat and organs form and begin to function. At 22 days after conception, the neural tube forms along the back of the embryo, developing into the spinal cord and brain.
Why do most organisms fail during the embryonic period?
About 20 percent of organisms fail during the embryonic period, usually due to gross chromosomal abnormalities. As in the case of the germinal period, often the mother does not yet know that she is pregnant. It is during this stage that the major structures of the body are taking form making the embryonic period the time when the organism is most vulnerable to the greatest amount of damage if exposed to harmful substances. Potential mothers are not often aware of the risks they introduce to the developing child during this time.
Which direction does prenatal development occur?
Growth during prenatal development occurs in two major directions: from head to tail (cephalocaudal development) and from the midline outward (proximodistal development). This means that those structures nearest the head develop before those nearest the feet and those structures nearest the torso develop before those away from the center of the body (such as hands and fingers).