Teratogens and Fetal Development
Teratogens can be described as agents that contribute to fetal injury and birth defects or an abnormality because of fetal exposure during pregnancy. Some of these agents that lead to fetal injury or birth defects include chemicals, environmental contaminants, infections, and drugs. These agents tend to result in such abnormality in fetal development when a woman is exposed to them during the term of the pregnancy. The agents are always discovered following an increased prevalence of a specific birth defect or abnormality. Pregnant women are increasingly susceptible to teratogens since these agents can be found in various settings at home in the working environment. Notably, the effect of the agents on fetal development is dependent on the kind of agent, duration, and extent of the exposure. Generally, teratogens and fetal development can be about legal and/or illegal drugs and the effects on the fetus while in uterus up until birth. Good legal drugs can be accutane, thalidomide, etc. And illegal drugs such as cocaine and heroin.
What is Teratogen?
As previously mentioned, teratogens can be described as agents that affect fetal development by contributing to fetal injury, abnormality or birth defects. These agents comprise chemicals, environmental contaminants, drugs, and infections that affect fetal development when a pregnant woman is exposed to them during the term of the pregnancy. Pregnant women are increasingly vulnerable to exposure to these agents since they can be found at home, in the environment, and in the workplace. The severity of the fetal injury or birth abnormality caused by the agent is determined by various factors including the amount, duration, and extent of the exposure to the specific teratogen (Brown, 2015). Moreover, the severity of the injury or defect is dependent on the overall vulnerability of the embryo and the mother.
Low exposures to these agents may not result in any effect on fetal development while intermediate exposures or doses generate a characteristic model of malformations. Severe malformations or effects on fetal development usually occur during high doses or exposures to teratogens. However, regardless of the level or extent of exposure women are increasingly vulnerable to the effects of these agents during the first trimester of the pregnancy. In addition, these agents generate certain abnormalities at certain times during pregnancy.
The vulnerability of women to teratogens at any time during the pregnancy is attributed to the different classifications of these agents. Some of the most common classifications include infectious agents, physical agents, maternal health factors, drugs, and environmental chemicals. These different classifications contribute to the fact that teratogens can be both legal and illegal drugs that are available in different setting in the society. While good legal drugs like accutane and thalidomide are used to assist women with morning sickness, they generate certain abnormalities in babies such as phocomelia, which is the lack of long bones. The most severe effects of thalidomide on fetal development take place when a woman is exposed to these agents within the first month of the pregnancy. The other example of good legal drugs that affect fetal development include carbamazepine and valproic acid, which contribute to abnormalities in brain development and the spinal cord (Brown, 2015). In contrast, illegal drugs like cocaine and heroin contribute to various effects on the fetus and embryo including several gastro-intestinal and cardiac abnormalities. Illegal drugs generate such effects because they contribute to tissue death, which is brought by inadequate blood supply.
Given the increased exposure and impact of teratogens on fetal development, teratology has emerged as a major issue of study in relation to prenatal development and congenital abnormalities brought by external physical or chemical agents. The field of teratology has attracted considerable attention in the recent past because of the need to lessen birth defects or fetal injury that is caused by preventable factors. Actually, teratology is an emerging field in clinical research as part of initiatives towards eliminating preventable effects on fetal development (Aboubakr et. al, 2014, p.1). The emergence of this field is attributed to the increase in birth defects in the recent past. Birth defects have increased in the recent past to an extent that nearly 7 to 10% of all children need extensive clinical care to diagnose and treat birth abnormalities. These birth defects in children need to be properly diagnosed and treated since they are compromising the quality of life of many people across the globe.
The increase in the number of birth defects in the recent past is attributed to the fact that nearly all therapeutic agents during prenatal care cross the placental blockade and enter fetal circulation. As a result, every therapeutic agent used during pregnancy has the capability and tendency to generate some kind of birth abnormalities unless there is evidence showing otherwise. In this case, a birth defect or fetal injury can be described as a structural abnormality of any kind that occurs at birth. These structural abnormalities can either be microscopic or macroscopic within the body or on the surface.
In the past few decades, it has become more evident that animal and human embryos are increasingly susceptible or subjected to toxic effects of various drugs that women are exposed to during pregnancy. Some of these drugs that generate toxic effects on human embryos during pregnancy include certain antibiotics that are used in the treatment of severe diseases taking place during the term of pregnancy. As previously mentioned, the severity of abnormalities and defects produced by teratogens and these antibiotics is linked to the genetic vulnerabilities carried by fetus and the mother.
Effects of Teratogens
Teratogenic agents can generate significant harm or effects on fetal development during all stages of human development. During the first two weeks after conception, the zygote is constantly is speedily separating and not yet entrenched. At this stage, teratogenic agents that pose significant harm or risk will generate impending death of the growing fetus. After the zygote is implanted within the next five weeks, the development of organs, which is known as organogenesis, begins. During this period, the embryo experiences significant morphological changes if subjected to these agents. The occurrence of morphological changes on the embryo is attributed to the rapid cellular separation and differentiation (Bercovici, 2010, p.4). During this stage, teratogenic agents that affect the central nervous system are likely to create neural tube defects. The neural tube defects occur since the neural plate does not close correctly resulting in the lack of formation of the neural tube.
The effects of teratogens on fetal development also occur in the final stage or third trimester of the pregnancy. This stage is commonly known as the fetal period and is characterized by increased sensitivity of the central nervous system to teratogenic agents. Unlike the previous stage, teratogens only cause minor morphological changes or abnormalities because of the sensitivity of the central nervous system. However, these agents also generate physiological defects during the fetal period i.e. changes in neurogenesis and synaptogenesis.
This analysis demonstrates that teratogenic agents have significant effects on embryonic and fetal development during pregnancy, which sometimes generates birth defects. The effect of these agents on embryonic and fetal development is attributed to the fact that the human central nervous system is very vulnerable to several exogenous factors or agents like physical injury, teratogens, and stress of delivery.
Apart from the common effects of teratogens on fetal development during the three stages of human development and pregnancy, there are other effects that are dependent on whether the agents are good legal or illegal drugs. As previously discussed, the good legal drugs may be agents with negative effects on fetal development since they are used to treat severe conditions that take place during pregnancy. Accutane and thalidomide are examples of good legal drugs that results in birth defects like lack of flipper-like feet and hands as well as lack of long bones despite being used to help pregnant women deal with morning sickness. In addition, valproic acid and carbamazepine are good legal drugs that generate brain abnormalities and spinal cord. On the contrary, the effects of illegal drugs on fetal development depend on the specific type of drug used. For instance, cocaine and heroin are illegal drugs that generate several cardiac and gastro-intestinal abnormalities and tissue death emerging from inadequate supply of blood.
Generally, the effects of teratogens on fetal development are based on the classification of the agent i.e. infectious agents, pharmaceutical drugs, and environmental agents. Consequently, a specific birth defect or fetal injury may originate from several mechanisms and probable exposures such as treatment interventions and medications (van Gelder et. al, 2010, p.378). While prescription drugs are commonly used during pregnancy, the risks of teratogenic agents are evident in approximately 90% of these prescription medications. The effect of the prescription drugs on fetal development is dependent on the type of drug administered, genetic vulnerability, duration and dose of exposure.
Description of Studies
This research is based on several studies on teratogenic agents and their effects on embryonic and fetal development. One of…