TERATOGENS AND PREGNANCY.   Term Paper ID:29992 Click to get this paper

Essay Subject: Scientific discussion of external factors that might affect pregnancy and foster congenital birth defects in newborns.... More...

10 Pages / 2250 Words 13 sources, 23 Citations, APA Format $40.00 Return to List of Papers

Paper Abstract: Scientific discussion of external factors that might affect pregnancy and foster congenital birth defects in newborns. Prenatal development. Effect of pharmaceuticals, legal chemical substances, alcohol, narcotics & tobacco use by women on pregnancy. Effect of absence of essential nutrients such as Zinc. Cites several other causes of congenital birth defects. Variables. Problem of serious diseases of pregnant women & necessary drugs. Paper Introduction: This research examines the phenomenon of teratogens, or factors external to the physical experience of pregnancy, during the period of gestation, which may affect pregnancy outcomes by fostering congenital birth defects in newborns. The research will set forth the clinical context in which teratogenic agents achieve relevance for the course of pregnancy in the modern period, and then discuss the impact that concern about teratogens may have on efficient and prudent pregnancy management. On the face of things, the generally accepted definition of a teratogen would appear to be straightforwardly informative. Mosby's initially defines a teratogen as "any substance, agent, or process that interferes with normal prenatal development, causing the formation of one or more developmental abnormalities in the fetus" (Teratogen, 1998, p. 89). However, amplification of the d Text of the Paper: The entire text of the paper is shown below. However, the text is somewhat scrambled. We want to give you as much information as we possibly can about our papers and essays, but we cannot give them away for free. In the text below you will find that while disordered, many of the phrases are essentially intact. From this text you will be able to get a solid sense of the writing style, the concepts addressed, and the sources used in the research paper. Management ofurolithiasis during pregnancy. Neggers, Y.H., Goldenberg, R.L., Tamura, T., Johnston, K.E.,Copper,R.E., & DuBard, M. In the case reportedby Anand, Brimble, and Ginsberg, once the diagnosis was accomplished, thedrug of choice was a heparin compound, heparin being an anticoagulantsubstance naturally occurring in the liver. The authors explain: The safety of a drug is best tested in a prospective, randomised, double-blind placebo-controlled cohort study, but for obvious ethical reasons, this cannot be achieved in groups of pregnant women without very good evidence supporting a lack of teratogenicity (De Silva & Others, 1999, p. (1998, April 15). (1999, September). The problem with controlling variables in researchon teratogens appears to be duplicated in clinical practice, with theresult that deliberate administration of a possible teratogen to a pregnantwoman is subject to a cost/benefit analysis along with recourse to researchthat as closely as possible approximates the symptom complex presenting fortreatment. In the case they cite, there was an iliofemoralthrombosis of a vein, or blockage of the vein at the area where the hip(ilium) meets the thigh (femur) that could be potentially fatal. This research examines the phenomenon of teratogens, or factorsexternal to the physical experience of pregnancy, during the period ofgestation, which may affect pregnancy outcomes by fostering congenitalbirth defects in newborns. This does not absolve clinicians of the needto evaluate intervention options with one eye on their possible teratogeniceffect. For example, somekinds of exercise actually increase cardiovascular activity, thusincreasing blood flows throughout the body. That doesnot, however, necessarily prove that mebendazole had health-givingproperties. Annals of the Rheumatic Diseases, 59,8 -8 9. Oneexample comes from a study conducted in Sri Lanka (De Silva & Others,1999), where hookworm infection, which has iron-deficiency anemia as a sideeffect, is common. Plasma and erythrocyte zincconcentrations and their relationship to dietary zinc intake and zincsupplementation during pregnancy in low-income African-American women.Journal of the American Dietetic Association, 97, 1269-75. Contemporary OB/GYN, 44, 148. Citing other studies of WG interventions, they imply that WGitself can be considered teratogenic from a clinical perspective;clinicians advise those known to have WG to plan pregnancy onset when theWG is known to be in remission. However, it is extremely important to emphasize that reportedresults of teratogenic identifications in laboratory animals do notnecessarily implicate an agent in human subjects. as informed consent" (Wolkomir, 1996,p. Riddell, J.V.B., & Denstedt, J.D. (1997, November). How it will strike cannot be predicted absolutely, though embryosappear to be most vulnerable between weeks three through twelve ofgestation, "when differentiation of the major organs and systems occurs"(p. This method of categorization allows Thomas to identifyseveral thousand possibly teratogenic agents, with roughly half of themhaving been shown to cause birth defects in laboratory animals. The authors of the WG casestudies report that four of six pregnancies resulted in live births, withone maternal fatality and one therapeutic abortion due to fetal braininflammation. Definitive as this description seems, the overarching fact is thatonly some 3 teratogens have been identified as having effect on humanpregnancy (Thomas, 1998). In the case ofdiscretionary substance abuse (narcotics, tobacco, alcohol) duringpregnancy, the literature seems uniform in its evaluation of the likelihoodof disappointing birth outcomes. The fact of teratogens in the picture of healthy pregnancy and birthoutcomes free of congenital defects looms large. No less significant is afact connected to it: that there are almost insurmountable methodologicalchallenges to empirically verifying the scope and limit of teratogenicfunctionality. Harvey, E.B., Boice, J.D., Jr. Only observed pathologies (e.g.,congenital birth defects) can be traced to a specific substance andcorrelated, or perhaps matched, to similar pregnancy outcomes in othersubjects, thus creating clusters or patterns of observation that helprefine understanding of teratogens: Among the known teratogens are chemical agents, including such drugs as thalidomide, alkylating agents, and alcohol; infectious agents, especially the rubella virus and cytomegalovirus; ionizing radiation, particularly x-rays; and environmental factors, such as the age and general health of the mother or any intrauterine trauma that may affect the fetus, especially during the later stages of pregnancy (Teratogen, 1998, p. Body count. For example, in the Sri Lanka study, women who had consumedmebendazole during pregnancy as a group were found to have had relativelyhigher birth weight babies than their nonconsuming counterparts. H. (1998). While theassociation between first-trimester mebendazole and incidence of congenitaldefect was measurable, the drug was not considered significantly butinstead relatively risky. The moreinvasive a procedure and more powerful a given substance is known to be,the more caution practitioners exercise in administering it, particularlyin the first trimester. (2 ),cite difficulties in treating Wegener's granulomatosis (WG), a diseasecharacterized by inflammation of the walls of the blood vessels andrestriction of blood flow to vital organs. (1996). The problem with warfarin as the first choice for apregnant woman is twofold: it can foster bleeding, and it crosses theplacenta, which implicates it as a possible teratogen. (1998). If WG is active and cyclophosphamide isused as the treatment, oral contraception is recommended because ofclinically observed teratogenic effect on fetuses and possiblesterilization of ovaries (Auzary, & Others, 2 ). This does not mean that cliniciansare not alert to the possibility of interference from some unidentifiedexternal source with the normal human gestation process. Kandel and Schaffran(1998) cite research showing "a significant relationship between maternalsmoking during pregnancy on the child smoking thirteen years later,"suggesting that prenatal exposure to smoking would have the effect ofpredisposing the child to tolerance of tobacco toxins. Auzary, C., Thi Huong, D., Wechsler, B., Vauthier-Brouzes, D., & Piette,J. Catalog of teratogenic agents. . St. De Silva, et al., cite the increased attention to prenatalhealth care more generally as a possible explanation for the phenomenon. Anand, Brimble, and Ginsberg (1997)report on a problem encountered by many women who are pregnant or who havejust given birth: venous thromboembolism (blood or tissue coagulation sitesinside the veins). But repeatedly in studies that form thebasis of such recommendations, problems with methodology emerge because ofthe difficulty of establishing human-subject experimental and controlgroups for administration and nonadminstration of suspected teratogens. Interestingly, a good deal of the discourse ofresponsible pregnancy management with regard to controlled substancesappears to focus on cultural rather than biophysical issues, possiblybecause maternal use of alcohol, narcotics, and tobacco during pregnancyand the neonatal period is discretionary. (1998). The literature contains specific recommendations against use ofcertain otherwise beneficial pharmaceuticals based on their teratogeniceffects on pregnancy outcomes. Exercise during pregnancy.American Family Physician, 57, 1846-53. The drug interventions usuallyused on WG consist of corticosteroids, cyclophosphamide, and/ormethotrexate, all of which can send WG into remission but all of which havebeen identified as teratogenic, especially in the first eight weeks ofgestation. Some serious diseases of pregnant women that require drug or othertherapy remain problematic because the cases come up at times when thefetus is most vulnerable to teratogens, in the early weeks of organdevelopment. Thepreferred approach appears to be to organize treatments according as thematernal needs are acute and/or the at-risk gestation period appears to bepast. Wang, T.W., & Apgar, B.S. 1145). Meanwhile, the absence of some nutrients appears to have a teratogeniceffect. Now thedrug therapy for this kind of condition is straightforward: anticoagulant.However, the compound of choice, warfarin (C19H16O4), was first identifiedas a rat poison, which alone would be one reason to be suspicious of itsteratogenic properties. M., &de Silva, H. Obviously maternal anemia can be harmful to a fetus, butthe question researchers asked was whether the risk of anemia would beoutweighed by the risk of congenital defects that could be traced toconsumption of the drug mebendazole. In that regard, Wolkomir (1996, p. Kandel,D., & C. Mosby. Schaffran. Thomas, H. Mosby's medical, nursing, & allied health dictionary.5th ed. 89). Toxic behavior on one hand, or what wouldpass as perfectly healthful behavior for persons who were not pregnant onthe other, has been implicated in the chain of causation for congenitalbirth defects. (2 , October). Apart from the constituents of a given substance suspected of being ateratogen, the teratogenic effect itself may be highly idiosyncratic fromfetus to fetus, or from host womb to womb, varying with the substance andits behavior per se, the targeted organism, and/or the stage ofdevelopment. S. Thusconsidered, it might appear that the relevance of teratogens to humanpregnancies can easily be classified and understood. 89). (1996, February). In other words, knowing how a given maternal organ systembehaves over the course of a pregnancy, the clinician can look as well athow a given substance behaves in the body and forecast the functionalinteraction of the two and likely implications for the fetus as aconsequence. Wang and Apgar areprogrammatically noncommittal about declaring exercise to have eitherbeneficial or teratogenic effect, though the weight of their evidence is onthe side of recommending prudent levels of maternal activity during thegestation period. However, they explain that hot tub use in early pregnancy, whichwould entail immersion of the lower body in heated water, has beenassociated with birth defects of the central nervous system. Mosby'sinitially defines a teratogen as "any substance, agent, or process thatinterferes with normal prenatal development, causing the formation of oneor more developmental abnormalities in the fetus" (Teratogen, 1998, p. Managing nausea in pregnancy: Yourfirst- and second-line options. That would mean that exercisecould be beneficial for mother and fetus alike. (1997, April 14). With reference to six case studies, Auzary, et al. Although maternal behaviorduring pregnancy is the proximate cause of FAS, and although any counselingor other intervention would be undertaken with mothers, it is the fetus,then the newborn, and not the mother, who is considered to be afflictedwith the disease. The research will set forth the clinical contextin which teratogenic agents achieve relevance for the course of pregnancyin the modern period, and then discuss the impact that concern aboutteratogens may have on efficient and prudent pregnancy management. There is compelling technical and epidemiologicalevidence that co-morbidity of substance abuse, in the form of use ofalcohol and narcotics, and pathological outcomes of pregnancy are realpossibilities (Dilulio, Bennet, & Walter, 1996). Sometimes maternal pathologies occur in the course of a pregnancy thatrequire clinical intervention. They point outthat the physiology of exercise is such that maternal muscular activitywould divert blood away from the abdominal region, and while this in theorycould lead to fetal hypoxemia, the fact is that results of studies of thephenomenon have been contradictory (Wang & Apgar, 1998). Effect of mebendazole therapy duringpregnancy on birth outcome. Intervention in acute-needs cases is sometimes unavoidable,irrespective of the time of gestation. (1985). Maternal anesthesia carries the risk of spontaneous abortion andpremature labor, as well as congenital birth defects (Riddell & Denstedt,1999). References Anand, S.S., Brimble, S., & Ginsberg, J.S. Further, the value ofa compiled list of agents toxic to good birth outcomes is difficult tooverstate. The authors of the Sri Lanka study cite the phenomenon of positiverecall bias, the name given to the fact that women giving birth to babieswith major congenital defects are likely to report exposure to possibleteratogens (De Silva & Others, 1999). A number of pharmaceutical and surgical substances that are innocuousto the general population in the context of health-care delivery protocolsare generally agreed to be teratogenic for pregnant women. Consultant, 36, 298-3 . Wang and Apgar (1998) suggest that too-vigorous exerciseleading to dehydration or exercise obliging the subject to bear too muchweight in the last trimester of pregnancy could produce teratogenic effect.They note that this conjecture is based chiefly on animal studies, nothuman studies, and caution that empirical research into the matter islimited. Epidemiology of substance abuse.Available: http://www.nyspi.cpmc.columbia.edu/NYSPI/PIDPT_EA.HTM. On the face of things, the generally accepted definition of ateratogen would appear to be straightforwardly informative. Results of teratogenic studies of human subjects--who obviously cannotbe subjected willy nilly to laboratory trials of suspected teratogens--areextremely rare, a point driven home repeatedly in the literature (e.g.,Wolkomir, 1996; Wayne & Apgar, 1998). But with regard to other agents, whetherpharmaceutical or behavioral, researchers seem constrained to point out thedifficulty of claiming too much for an agent without empiricalsubstantiation. PrenatalX-ray exposure and childhood cancer in twins. Pharmaceuticals and other chemical substances are not the only sourceof teratogens during pregnancy. This leads to the view that "nonurgent" surgery shouldbe postponed in humans until the organ system has fully formed (usually 12weeks): "If anesthesia is necessary during the first trimester, regional orneuroleptic techniques are preferred" (Riddell & Denstedt, 1999). To put it another way, thestudy could not prove the absence of dietary zinc supplements to beteratogenic, even though it could show an apparent effect of zincsupplementation on pregnant women. Baltimore: JohnsHopkins University Press. S., Ismail, M. Dilulio, J., Bennet, J., & Walter, J. Reflecting the indeterminacy of definition implied in Mosby's andproblems with sample formation and study design, Thomas's catalogue (1998)of teratogens divides them into three general categories: unlikely, proven,and possible. Teratogen. Neggers and Others (1997), for example, cite studies showing thatzinc deficiency is highly teratogenic in rat subjects, and in their studythey compared zinc-level increases in pregnant women whose diets were orwere not supplemented by dietary zinc. Bagheri, M., Burd, L., Martsolf, J., & Klug, M. Indeed, even certain common diagnostic procedures carry teratogenicrisks, for fetal x-ray exposure has been identified as a teratogen forinfant/childhood cancer and retardation (Harvey & Others, 1985). Indeed, it would appear that a clear responsibility of any clinicianwho is treating a woman of childbearing age would be to determine whethershe is pregnant or plans to become so before undertaking radiographicdiagnostics of any kind. . The Lancet, 353, 1145. New England Journal ofMedicine, 312, 541-545. (1999, April 3). And this is problematic because of the ethical trap thatwould be associated with attempting to structure a study in which somepregnant women were deliberately exposed to a suspected teratogen whileothers were not. Louis: C.V. Thus the question for practitioners faced with the option ofdoing a procedure and/or administering surgical or drug therapy to apregnant women must consider such an option in the context of pregnancymanagement. That means, as Bagheri, et al.,point out, that FAS (for example) is an entirely preventable disease; it isless clear whether substance abuse occurring before pregnancy onset posesdevelopmental problems for the fetus. 298)cites the withdrawal in 1983 of longtime antinausea remedy Benedictin,which had been used by pregnant women for 3 years: Consisting, in its final formulation, of 1 mg each of pyridoxine (vitamin B6) and doxylamine, it was shown to be both safe and effective in randomized, controlled trials. However, researchinto teratogens reveals a record of disagreement about the birth-defectpotential of specific substances. New York:Simon and Schuster. (1998). Honeyman, M., & Others. Wolkomir, M.S. 89).However, amplification of the definition demonstrates the complexfunctionality of teratogens: What a teratogen is cannot be definitivelystated. Thus Wolkomir, aphysician, reports that he has prescribed a pyridoxine and doxylaminecombination, inasmuch as he takes the position that Benedictin, widelytested as it was, was wrongly labeled as a teratogen and taken off themarket. P. Fetal alcoholsyndrome (FAS) has been identified as the single principal teratogen formental retardation, and it is implicated in neural developmental problemsas well (Bagheri, Burd, Martsolf, & Klug, 1998). Despite the fact that Bendectin was one of the most extensively tested medications ever used in pregnancy, the cost of defending the product in suits charging that it caused anomalies led to its removal from the formulary.The caution with which the medical community approaches the use of drugsduring pregnancy is consistent with the view that teratogenic effects inhumans are equally difficult to prove and disprove. Fetal alcoholsyndrome: Maternal and neonatal characteristics. Managementof iliofemoral thrombosis in a pregnant patient with heparin resistance.Archives of Internal Medicine, 157, 815-16. 299). Corticosteroids appear to be less teratogenic if administered inconjunction with immunosuppression drugs. This was a retrospective analysis ofbirth outcomes in that region, not a double-blind study that followed thecourse of pregnancies and monitored maternal behavior and drug consumption.It was found that 2.5% of women (sample = 4 7) who, against medical advice,had taken the anti-hookworm treatment mebendazole in the first trimester ofpregnancy gave birth to babies with major congenital defects. Pregnancy in patients with Wegener's granulomatosis:Report of five cases in three women. But because of the potential for litigation in the event of apositive congenital condition, he adds, "I clearly explain the situation topatients before I prescribe it . But they note that controversysurrounds the issue of whether dietary zinc supplements for pregnant womencan exercise beneficial effect, since the level of zinc in red blood cellsrises anyway over the course of a pregnancy. L., Gunasekera, D. Animal lab studies indicate that inhaled gases can pass to theplacenta and can be implicated in organ-system deformities during the firstweeks of pregnancy. Journal of PerinatalMedicine, 26, 263-269 De Silva, N.R., Sirisena, J. If this paper is not what you are looking for, you can search again: Search for: or Click here to request an essay written just for you.