Thursday, February 18, 2010

Teratogens? How do they impact my child's development? What is exposure? What now?

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). Caffeine, smoking and drugs all can lead to low birth weight (Department). Other Teratogens include medications, pollutants, injury, disease or illness, etc. (Berk, 2008). Teratogens may lead to birth defects, development impairments, or even death (Michigan). Teratogens that result in cognitive delay or impairment in the future are considered Behavioral Teratogens (Michigan).

The level of influence the Teratogens have depend on several factors. The threshold effect is one of these factors. The threshold effect occurs when a teratogen that is relatively harmless in a small quantity becomes dangerous at a specific level, or threshold (Michigan). Along with the threshold effect, the duration of exposure is relevant to the impact (Berk, 2008). Another factor is referred to as the interaction effect, resulting when a stimulus is harmless independently presented, but in combination with other stimuli becomes dangerous to the embryo (Michigan). Heredity is also an important indicator whether a teratogen will have an increased or decreased influence on the embryo (Berk, 2008). Genetics determine if an embryo is susceptible or resilient to the specific influence (Berk, 2008).

Timing, or age of the fetus, is highly relevant to the impact of the teratogen (Berk, 2008). Before the fifteenth day after conception, Teratogens have a decreased effect (Berk, 2008). The embryonic period, on the other hand, is the most vulnerable to external influences (Berk, 2008). Organ damage may still result if the Teratogens are presented during the fetal period, but the risk is significantly decreased (Berk, 2008). Decreased nutrition, for example, during the embryonic stage has been linked to physical deformities, while malnutrition during the fetal period is linked to small head circumference and low birth weight (Department). The timing or age of the developing human is critical due to the processes of development occurring during that period. In the third week after conception, the heart is forming, the beginning of brain and spinal cord development is occurring, and the gastrointestinal tract is forming (Boeree). During the 15th day to the third week, the presence of specific Teratogens has been related to the infant being born without limbs and the presence of the heart outside of the cavity (Boeree). During the week four through five, the heart has begun a rhythm, the vertebra is forming, basic ears and eye development is occurring, while the voice box is presenting (Boeree). Thus Teratogens insulting the embryo may cause cleft palate, missing hands and feet, esophageal difficulties, impaired vision and hearing (Boeree). A further example of the timing factor is from the Nineteen Sixties when Thalidomide was prescribed to pregnant women (Berk, 2008). Mothers who ingested this medication who were carrying a four to six week old embryo had higher rates of births with limb deformities, heart damage, kidney and genital deformities (Berk, 2008).

The manners in which Teratogens impact the developing human vary. Caffeine, smoking, drugs, stress, and inadequate nutrition are all related to physical development (Department). In fact, statistics reveal that forty five percent of all pregnancies result in miscarriage (Department). Not all of these are related to Teratogens; however, that number is staggering. One study found that the age of the mother is relevant to development of the fetus, and the younger age increases the risk of healthy infants (Department). Rresearch also indicates that mothers in their twenties are at a higher risk for poor prenatal care and malnutrition (Department). Thus, one has to wonder if the threat of Teratogens counters the increase in health relative to a younger birthing age. The impact of stress has been studied in animals and humans (Department). Research indicates that this teratogen is linked to decreased birth weight and increased behavioral and emotional difficulties (Department). Pollutants such as mercury have been linked to mental retardation, physical defects, language and speech delays, oral motor deficits, and brain damage (Berk, 2008). Lead, another pollutant that has a teratogen effect on infants, is related to the risk of prematurity, low birth weight, brain damage, and physical defects (Berk, 2008). Even slight levels of lead increase the risk as being a behavioral teratogen (Berk, 2008).

One final note worth mentioning, although not a teratogen, is the post natal environment. Post natal environment plays a significant role in the impact a teratogen has on the infant after birth. Research finds that the response of the caregiver and the environment the infant is exposed to assists in determining the degree to which the teratogen will influence the rest of the individual’s life. For example, infants born from prenatal exposure to cocaine, heroin, and methadone have decreased birth weight, physical deformities, and respiratory difficulties (Boeree). Behaviorally, the results are abnormal sleep patterns, high pitched crying, decreased attention to environmental stimuli, delayed motor development (Boeree). However, studies have determined that some infants change these behavioral outcomes, but the change is dependent upon a safe and nurturing environment with a responsive caregiver (Boeree). So, although the physical outcomes can not be altered after teratogen exposure, the behavioral Teratogens could have a decreased impact on the life of the child.

Valerie Poling
Child Psychology

Berk, L. (2008). Prenatal Development. In L. Berk, Infants, Children, and Adolescents (pp. 69-163). Boston: Pearson.
Boeree, G. C. (n.d.). Prenatal Development. Retrieved January 18, 2010, from General Psychology:
Department, C. P. (n.d.). Hazards to Prenatal Development: Teratogens. Retrieved January 18, 2010, from^colunga/P468/teratogens.PDF
Michigan, U. o. (n.d.). Teratogens. Retrieved January 17, 2010, from University of Michigan Psychology Course:^psycourse/350/jaeckelj/terats.htm

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Blogger amy.browneyedgirl said...

nice read .. thank u for this important information.

March 20, 2010 at 6:14 PM  
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May 24, 2010 at 9:52 AM  

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