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Now of course with the holidays coming up everyone knows to drink and behave responsibly. Everyone including the young mothers who are carrying children. They know all about the physical and cognitive effects that a drink may have on their fetus. According to health surveys 19 percent of 4 million mothers used some form of alcohol in their prenatal phase, in 1992. And this number is continually increasing, making Fetal Alcohol Syndrome one of the leading causes of birth defects in the United States (Novels, 1997). According to Mosby: A teratogen is any substance that interferes with normal prenatal development, causing the formation of one or more developmental abnormalities in the fetus (Stratton.
K, Battaglia. F, 1996). Teratogens are any substances that the placenta can not place out. The placenta is the mass of tissue that is filled with blood and that nourishes the fetus. These substances affect the fetus directly because the mothers and the childs blood stream are very close together. That is why these substances are able to penetrate and damage the fetus.
The intensity of the damage is dependent from the kind of harmful substance, the stage at which it affects the fetus and the genetic predisposition of the fetus. The major damages can occur between the third and the twelfth week, that is when the major organs start to form. Some popular teratogens are thalidomide, alkyl ating agents, alcohol, drugs, virus (rubella) and any uterine infections from the mother. (Howe, C. , 1996) Anticonvulsants are drugs taken by women during pregnancy. This drug is used to treat epilepsy. The teratogenic effects of this drug are hazardous for the fetus. One author says: Associations with neural tube defects and facial clefts are well recognized, but congenital abnormalities alone are a crude indicator of teratogenic ity (Streissguth, A. , 1997).
There is also the risk of educational impairment that will be displayed later in childhood. Many women make the mistakes of taking anti -convulsant's, prescribed by their physician, while they are seizure-free. Khattak states that: Occupational exposure to organic solvents during pregnancy is associated with an increased risk of major fetal deformations (Shall Khattak, 1999). The controlled study that was performed shows that women experience teratogenic effects when they were exposed to organic solvents. The fetuses from mothers that were exposed to this solvent resulted with major congenital deformations. The percentage of the newborns with abnormalities was 95 %.
The women were at higher risks if they worked in the health care industry or in textile and the clothing industries. These solvents resulted in central nervous system defects in mice, congenital malformation in rabbits and the retardation of skeletal growth in rats. The dosage used in the lab was high and from a single agent which creates a controversy. Because women in their work environment may inhale a variety of agents in lower doses. (Battaglia, 1996) One authors states: Evidence suggests that premature infants exposed to cocaine before birth may be at risk for later developmental difficulties. Prematurity has been related with prenatal exposure. (Abel, 1996. ). The newborns whose mothers were exposed in the prenatal stage to cocaine showed a variety of symptoms.
Their head was smaller, they had irregular sleeping patterns, were more depressed and spent more time in the intensive neonatal care unit. The babies had also lower norepinephrine, dopamine and cortisol levels. These infants also spent less time sleeping peacefully. They were more irritated and agitated. They scored lower than regular infants on the Brazelton Behavior Assessment Scale. Infants also were less responsive to the stimuli in their environment and interacted less with other infants and their parents.
Also these infants had d efficiencies in motor development. The babies showed less eye to hand coordination abilities than other children 2 years of age. (Abel, 1996). The infants that were exposed to cocaine in the prenatal stage were born with retarded growth, a small head and neurological abnormalities. (du Florey, D. , 1992). After the study was concluded the most negative results were in the group with the most exposure of cocaine. The future of the growth and mental retardation problem is uncertain but monitoring needs to be taken seriously by future parents so these cases can be avoided. (Polygenis, D. , 1998) According to Streissguth: DES is a hormone that was prescribed by doctors for pregnant women in the 1950 s and early 1960 s. Years later doctors discovered that the daughters of the women who received DES were at high risk for infertility, premature labor, and cancer of the vagina and cervix. (Streissguth, A. 1994).
Several chemical companies believed that DES would be able to prevent miscarriages. This a hormone similar to estrogen. Only 10 years doctors experienced a whole gamut of symptoms. The symptoms ranged from infertility to cancer of the cervix and vagina. The women who show these symptoms must have been exposed to DES 18 weeks before birth. So form this researchers conclude that the exposure occurred 4 - 5 months after conceptions.
At this time the vagina and other reproductive organs formed so this hormone must have influenced their development. These women now receive pap smear exams and pelvic exams once every year. In colposcopy the doctor views the tissue of the vagina and cervix through a magnifying lens. This is an optimal procedure because abnormal cancer cells can be detected. (Good lett, 1992) Wilkie suggests that: Prenatal maternal smoking may represent an additional risk factor for adult criminal outcomes. Maternal prenatal smoking was particularly related to persistent criminal behavior rather than to arrests confined to adolescence. (Wilkie, 1997) The researchers kept track of the offspring from the mothers. Then at the age of 34 they checked all of the offspring's criminal records and their social status (marriage, friends).
The researchers found that there was a correlation between the mothers who smoked during their pregnancy and their children who had criminal records. Maternal prenatal smoking has been linked with many other behaviors, such as impulsivity, truancy, conduct disorder, attentional difficulties, chronic ischemia, hypoxia, hyper tonicity, increased tremors, and increased startle response in infants. So that researchers conclude a possible link between maternal smoking and central nervous system deficits. (Wilkie, 1997) Another teratogen that is being researched is thalidomide. This chemical has caused birth defects in Europe. Now they are hoping to cure erythema nodosum leprosy, AIDS, skin inflammations, ulcers and organ rejection after the transplant is performed. Thalidomide stops the development of the blood vessels in the fetus while at the same time it controls the immune system and shows anti-inflammatory properties.
Some of the symptoms seen in infants are nerve disorders, sedation and constipation's. It is still being researched about its curing abilities but it still presents great teratogenic risks for the fetus. (Barr, 1999) Johnson states that: Fetal alcohol syndrome (FAS) is a group of birth (congenital) defects occuring in an infant as a result of maternal alcohol abuse during pregnancy. (Johnson, 1997) This disease is the leading cause of mental defects in the western world. And the worst is that it is not curable. The neurological abnormalities include mental retardation, IQ of 63 (average), a small head, motor retardation and hearing disturbances.
The facial abnormalities are small eyes, small eye openings and abnormal lips. These infants have growth defects, have small size and weigh less. Attention deficit disorder and hyperactivity are some of the behavioral disturbances. Cardiac and circulatory system defects are also present at birth in these infants. The quantity of alcohol that causes FAS is not clear but cases have been reported where binge drinking has been the major factor. (Johnson, 1997) Doctors in California are considering the case if the birth defects of a baby were cause from tamoxifen. Tamoxifen is usually used to treat breast cancer and is anti-estrogen.
According to Henderson: Children of pregnant women taking breast cancer drug, tamoxifen may be prone to hermaphrodite birth defects. In another case the infants genitalia were abnormal. There is no sure evidence that tamoxifen causes birth defects. The companys representative says that the label on the medication prohibits distribution to pregnant women.
There have only been few cases where birth defects have occurred. (Henderson, 1997. ) Walling writes that: The use of doxycycline during pregnancy is strictly prohibited. (Walling, 1997) But in some cases this drug is needed to treat maternal infections. In this case this teratogen has led to the termination of pregnancy after exposure of the fetus to it. The percentage of congenital abnormalities is 90 % in Hungary. It is not safe to say that doxycycline causes birth defects because the registries in Hungary prove this.
Researchers believe that this drug may have a strong effect when taken during the formation of the organs. It has small teratogenic risks and it prohibited for use during pregnancy in the U. S. Harvey and Koch state that: Untreated maternal phenylketonuria increases risks for developmental problems in offspring. (Harvey, Koch, 2000. ) In the offering of women with PKU there is a 92 % risk for mental retardation, 73 % risk for microcephaly, 40 % risk for low birth weight and 12 % risk for congenital heart defect. It is clear that the abnormal uterine environment harms the fetus.
A diet poor in phenylalanine reduced these risks. The delayed metabolic control in maternal PKU causes serious developmental and cognitive problems. The safest precaution is that women achieve their metabolic control before pregnancy. If the disease progresses the child will have less language, memory and quantitative skills while their motor and behavioral abilities are less influenced. Children that have exhibit autistic and self-abusive features in basically cognition and mental processing.
According to Plotkin and Katz: During the epidemic an expanded congenital rubella syndrome (CRS) involved cataracts, cardiac abnormalities, deafness, encephalitis, wasting, hepatitis, pneumonia and endocrinopathies. (Plotkin, Katz, 1999) CRS is an important cause of child birth abnormalities in developing countries. Some of the symptoms of this disease are congenital heart disease and cataracts. If a mass vaccination would be accomplished then millions of premature deaths could be avoided. (Plotkin, Katz, 2000) Prenatal development consists of three stages, zygote, embryonic and fetal stage. It the sperm is really lucky it will get inside the egg and form the zygote.
Here is when conception begins. Only half of these fertilized eggs survive. Then cells begin to replicate from two &# 61664; four &# 61664; eight &# 61664; 16 &# 61664; 100. When one hundred cells is reached then each cell begins to do a separate function, it differentiates. Each cell has its own job now. Some cells will create the heart, some will assemble the brain.
After 10 days the cells get attached to the uterine wall and will stay there for around 37 weeks. The placenta is formed and it attaches to the uterine wall so nourishment can be transferred. From 2 - 8 weeks it is called an embryo. Organ genesis starts to occur. The heart is functional now.
At this time the sex gets established. The y chromosome will influence maleness in the embryo. After 9 weeks until birth the embryo is called a fetus. It stays in the uterus the remaining time so that it can adapt to life once it leaves the uterus.
Babies are connected to their mothers habits, gestures and especially voice. That is the one thing they prefer the most. (Volkhardt, 1996) Teratogens and prenatal development are connected directly to each other. Teratogens are especially damaging and lethal in the prenatal stage. Different screening and exams are necessary to insure that children will be born normal and with the least complications.
One of these screenings is ultra sound. The physician uses sound waves in a noninvasive procedure to view the fetus in a computer screen for any abnormalities. (Campbell, Bibliography: web VA-Yale Schizophrenia Biological Research Center web web web Biology of Schizophrenia and Affective Disease Stanley J. Watson (Editor), Association for Research in Nervous and ment 1996 Case Studies in Schizophrenia: Based on the Readings of Edgar Cayce David, M. A.
Mcmillan / Published 1997 Experiences of Schizophrenia: An Integration of the Personal, Scientific, and Therapeutic Michael, M. D. Robbins 1999
Free research essays on topics related to: birth defects, mental retardation, fetal alcohol syndrome, central nervous system, maternal smoking
Research essay sample on Fetal Alcohol Syndrome Central Nervous System
