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	Teratogens - Sharp HealthCare in San Diego
		It could be a prescribed medication, a street drug, alcohol use, or a disease present in the mother which could increase the chance for the baby to be born with a birth defect.
		Teratogens are thought to have the ability to affect the fetus about 10 to14 days after conception.
		If a teratogen has the potential to interfere with the closure of the neural tube, for example, the exposure to the teratogen must occur in the first 3.5 to 4.5 weeks of the pregnancy, since this is when the neural tube is closing.
	www.sharp.com /healthInfo/content.cfm?pageid=P02151 (452 words)

	Teratogens and Teratogenesis
		Teratogens can either physical or chemical agents that cause the foetus to become malformed (a common term used is congenital malformation or birth defects) or abnormal.
		In this respect, different kind of teratogenic effects may be seen with a similar exposure.
		The diagram 1 shows the result of an experiment that was conducted using rats to demonstrate the varied teratogenic effects encountered upon exposure of the same chemical substance.
	www.prn2.usm.my /mainsite/bulletin/sun/1995/sun23.html (734 words)

	* Teratogens - (Pregnancy & Parenting): Definition
		A teratogen is any medication, chemical, infectious disease, or environmental agent that might interfere with the normal development of a foetus and result in the loss of a pregnancy, a birth defect,...
		A teratogen is any medication, chemical, infectious disease, or environmental agent that might interfere with the normal development of a fetus and result in the loss of a pregnancy, a birth defect, or a pregnancy complication.
		Teratogens Agents such as drugs, chemicals and infections that can cause birth defects when a mother is exposed to them during pregnancy.
	en.mimi.hu /pregnancy/teratogens.html (332 words)

	Teratogens: Know The Risks
		The truth about teratogens is known by many people, but not all are informed about this critical happening to unborn infants.
		Teratogens may cause cell death in certain tissues, for example, leading to altered development, or they may interfere with cellular differentiation, causing disorganization at the molecular level.
		Teratogen information services are a relatively new offering available through genetic centers and hospitals throughout the country.
	www.k12.nf.ca /glovertown/Stellar/Biology/Teratogens.html (1218 words)

	Health & Sexuality - Volume 7, Number 2 - Preventing Pregnancy in Women Who Use Teratogens
		The type or severity of abnormalities caused by a teratogenic agent is also dependent on the genotype of both the mother and the fetus (genetic susceptibility).
		For a drug to be considered a human teratogen, a dose-response must be observed: the greater the exposure during pregnancy, the more severe the effect.
		None of the teratogens used in dermatology is as popular in a population at risk for unintended pregnancy as isotretinoin.
	www.arhp.org /healthcareproviders/onlinepublications/healthandsexuality/teratogens/prevpreg-a-1.cfm?ID=242 (3207 words)

	Reference.com/Encyclopedia/Teratogenesis
		Teratogenic effects also help to determine the pregnancy category assigned by regulatory authorities; in the United States, a pregnancy category of X, D, or C may be assigned if teratogenic effects (or other risks in pregnancy) are documented or cannot be excluded.
		Isotretinoin (13-cis-retinoic-acid; brand name Accutane), often used to treat severe acne, is such a strong teratogen that just a single dose taken by a pregnant woman may result in serious birth defects.
		Because of this effect, most countries have systems in place to ensure that it is not given to pregnant women, and that the patient is aware of how important it is to prevent pregnancy during and at least one month after treatment.
	www.reference.com /browse/wiki/Teratogenic (450 words)

	Biology 442, Human Genetics - Teratogens
		Teratogens are non-genetic factors that interfere with normal embryonic and fetal differentiation and morphogenesis.
		Because the effects of teratogens are seen at birth and are therefore a congenital defect, they are often thought to be genetic and can mimic genetic disorders.
		The study of teratogens is part of training in human genetics because it is important to distinguish the problems they cause from genetic disorders.
	www.carolguze.com /text/442-13-teratogens.shtml (2413 words)

	About 10% of congenital defects are caused by exogenous factors
		The fetus is most vulnerable to teratogenic exposure during the period of organogenesis.
		Although the fetus is resistant to teratogens during this period, the CNS may be affected leading to functional impairment.
		Although there are 1200 known potential teratogens in the animals, only 30 are known to have produced problems in the humans.
	ramanathans.com /Teratogens.htm (1042 words)

	TERATOGENS
		Usually an increased prevalence of a particular birth defect leads to the discovery of a teratogenic agent.
		Cases of phocomelia in the early 1960's in Germany and Australia led to the identification of thalidomide as a human teratogen.
		The public awareness of hazardous agents in the home and the workplace, and awareness of the teratogenic potential of drugs or medications during pregnancy has led to the establishment of teratogen information services in most states or regions of the country.
	www.usd.edu /med/som/genetics/curriculum/2DTERAT4.htm (825 words)

	Systematic Identification of Drugs That Cause Birth Defects — A New Opportunity - ALLAN A MITCHELL, MD / New England ...
		Teratogenic effects in humans cannot be predicted reliably from the class of a drug or from what is known about its pharmacology and toxicology.
		Furthermore, teratogens are not detected in the human trials that are conducted before approval for marketing is granted, since such studies are too small, and more important, they usually — and appropriately — exclude women who might become pregnant, particularly if there is any suspicion generated from animal studies that a drug might be teratogenic.
		However, the relatively small samples recruited in such studies provide insufficient statistical power to identify moderate-risk teratogens because the base-line risk of a specific defect may be 1 in 1000 or less and the risk among exposed fetuses may be in the range of 2 to 10 per 1000.
	www.mindfully.org /Health/2003/Drugs-Birth-Defects25dec03.htm (2346 words)

	Human Teratogens: A critical evaluation
		Teratogens must reach the developing conceptus in sufficient amounts to cause their effects.
		Exposure of embryos to teratogens during the preimplantation stage usually does not cause congenital malformations, unless the agent persists in the body beyond this period.
		In counselling the pregnant patient exposed to a potential human teratogen, it is important to emphasize the significance of exposure to the patient.
	www.nvp-volumes.org /p2_4.htm (3467 words)

	Birth Defects Research for Children, Inc.
		Evidence that immunosuppressive agents may be teratogenic can be found as far back as the early sixties in research on thalidomide, the popular sedative which caused a worldwide epidemic of children with phocomelic limbs and other serious birth defects.
		In addition to having immunosuppressive effects, diphenylhydantoin is also teratogenic to the developing fetus and has been associated with an increased incidence of congenital malformations, such as cleft lip/ palate and heart malformation, and a pattern of congenital malformations called Fetal Hydantoin Syndrome.
		One possible teratogenic outcome from prenatal exposure to immunotoxins may be impairment in the development of the immune system.
	www.birthdefects.org /Research/immterat.htm (4373 words)

	Teratogens - New Advances, January 2, 2007 (Site not responding. Last check: 2007-11-04)
		Whether drugs, chemicals, birth defects, congenital malformations, causes occur in a conceptus exposed to a potentially teratogenic agent depends in large part on two factors: 1) gestational timing of the exposure and 2) the genetic makeup of the conceptus and the mother.
		Exposure to a teratogenic agent during organogenesis may result in a gross defect involving the organ undergoing formation at that time.
		The teratogenic agent may reach the developing embryo or fetus either by direct passage through maternal tissues (eg, ionizing radiation) or by placental transfer.
	www.ccspublishing.com /journals2a/teratogens.htm (392 words)

	An Alternative in vitro Method to Detect Teratogens
		Furthermore, this assay can be used not only as a screen to identify teratogens but also in mechanistic studies of abnormal development, gene involvement in resistance to teratogens and the possible role of heat shock (stress) proteins in preventing or minimizing birth defects.
		Teratogens are estimated to account for four to five percent of all human birth defects.
		A chemical is classified as eliciting a teratogenic response if it results in a statistically significant reduction in the number of myotubes and ganglia when compared with controls.
	www.psyeta.org /hia/vol8/bournais.html (2579 words)

	Prenatal Development
		It is during this critical period of differentiation (most of the first trimester or three-month period) that the growing fetus is most susceptible to damage from external sources (teratogens) including viral infections such as rubella, x-rays and other radiation, and poor nutrition.
		A child who has one developmental problem may have other problems that arose at the same time: Kidney problems and hearing problems, for example, are often found together because both kidneys and the inner ears develop at the same time.
		Teratogens may still cause heart problems and stunting of the fingers and toes.
	webspace.ship.edu /cgboer/genpsyfetaldev.html (1431 words)

	Teratogens
		A teratogen is an agent that produces defects in the developing embryo or fetus.
		Environmental teratogens are often seasonal, don't follow family lines, and affect multiple breeds.
		During the first 1/3 of gestation, the teratogen may cause malformation or death, depending on the importance to survival of organs affected.
	web.vet.cornell.edu /CVM/HANDOUTS/plants/Teratogens.html (1170 words)

	Teratogen Information on Healthline
		In the early 1960s it was shown that more than 7,000 women who took the anti-nausea drug thalidomide during their pregnancy had children with very short or absent arms and legs.
		Of course many teratogens, like thalidomide, work on a number of different developmental processes at different times (sometimes they are consecutive times, or they may be non-consecutive: for example from days 16 to 20 and days 24 to 48).
		The period of susceptibility of the fetus to most teratogens is between the third and eighth week after conception.
	www.healthline.com /galecontent/teratogen-2/1 (749 words)

	Influences on prenatal development (Site not responding. Last check: 2007-11-04)
		A specific teratogen may damage the body structures, the growth rate, the neurological networks, or all three.
		One reason is that many teratogens have an interaction effect; that is, one poison intensifies the effects of another.
		Not only is the specific teratogen important in determining the effects on prenatal development, but so is the time during pregnancy when the teratogen influences the fetus.
	sesd.sk.ca /psychology/Psych30/Ejournal-prenatal/influences_on_prenatal.htm (1588 words)

	Teratogenic drugs inhibit tumour cell attachment to lectin-coated surfaces
		Because of the importance of morphogenic cell−cell interactions in development it follows that agents that interfere with these interactions, regardless of the interference mechanism, are potential teratogens.
		We have found a very high correlation between inhibitory activity in the in vitro assay and reported teratogenic activity in human or animal studies.
		This suggests that many teratogenic agents may act by interfering, in an as yet unknown way, in normal cell to cell interactions.
	www.nature.com /nature/journal/v282/n5738/abs/282507a0.html (342 words)

	Natural Teratogens Page
		As with many other teratogens, the mechanism underlying these defects remains to be elucidated.
		It was finally published in 1929 that X-rays are teratogenic, linking X-ray exposure during pregnancy to small head size and mental retardation.
		The bombing of the Japanese cities of Hiroshima and Nagasaki (in 1945) induced an increase in newborns with microcephaly and mental retardation.
	teratology.org /jfs/NaturalTeratogens.html (617 words)

	Identifying Teratogens (Site not responding. Last check: 2007-11-04)
		Animal studies are the primary study method to determine whether a medication, or other environmental exposure, is safe during human pregnancy.
		Thalidomide has recently been approved by the FDA for the treatment of certain diseases, but it is only available by a physician's prescription.
		Observations from human exposure (prior to federal regulations for drug testing) are another important way to determine whether a medication is a teratogen.
	www.stlouischildrens.org /tabid/88/itemid/1158/Identifying-Teratogens.aspx (551 words)

	Mirror KB Article - Environmental Teratogens and effects on unborn foals
		The placenta does have the capability to screen out many injurious substances on the basis of size, but countless teratogens such as disease-causing organisms and chemicals are small enough to readily cross the barrier and enter the developing fetus.
		During this time of extreme vulnerability, teratogens damage the cells by arresting cell growth or by changing their normal growth patterns for a particular area.
		Keeping the mare healthy is of primary consideration during her pregnancy, but the use of common drugs administered to treat pregnant mares have a decisive outcome on the welfare of their foals.
	www.mirrorkbranch.com /article22.html (977 words)

	Teratogens - New Advances, January 2, 2007 (Site not responding. Last check: 2007-11-04)
		Maternal exposure to drugs or environmental chemicals may be responsible for 4-6% of these anomalies, or approximately 1 in 400 liveborn infants.
		Morphogenetic stage of the organism's development is a key factor in susceptibility to a potential teratogen.
		An important determinant of teratogenic potential is mode of exposure.
	www.medical-library.org /journals2a/teratogens.htm (392 words)

	ARS \| Publication request: Development of An Enzyme-Linked Immunosorbent Assay for the Veratrum Plant Teratogens: ...
		The steroidal alkaloids, cyclopamine and jervine, were isolated from Veratrum and shown to be primarily responsible for the malformations.
		Cyclopamine and jervine are potent teratogens that inhibit Sonic hedgehog (Shh) signaling during gastrulation stage embryonic development, producing cyclopia and holoprosencephaly.
		The simple extraction-ELISA methods developed in this study demonstrate the potential of using these techniques for the rapid screening of biological samples to detect the presence and concentration of cyclopamine and jervine and will be beneficial to pharmacological studies and livestock diagnostics.
	www.ars.usda.gov /research/publications/Publications.htm?seq_no_115=139415 (455 words)

	Teratogens
		To put a definition plainly, teratogens are agents responsible for many known birth defects.
		In this paper, you will find interesting facts based on research, the relationship between teratogens and developmental psychology and some personal views based on the information and research found for this piece.
		To be slightly more specific some commonly heard of agents classified as teratogens are given as examples.
	www.radessays.com /link.php?site=re&aff=netessays&dest=viewpaper.php?request=96248 (212 words)

	Guidelines on Handling Chemical Carcinogens, Teratogens and Mutagens
		The statutory requirements relate specifically to those agents which must be labelled "carcinogenic - category 1" or "carcinogen - category 2" under the Chemicals (Hazard Information and Packaging) Regulations 1993 (CHIP) - (Appendix 2 of this document) and to any substances listed in Schedule 8 of the CoSHH Regulations 1994.
		Teratogens produce abnormalities in the growing embryo or foetus
		The guidelines concentrate on carcinogens but the procedural requirements apply equally to teratogens and mutagens.
	www.shef.ac.uk /safety/cctm/2defin.html (146 words)

	442lecture28
		Time, the gestational age of the fetus at the time of the exposure to the teratogen.
		There is an "all or none" period in the first two weeks where the fetus is generally not susceptivle to teratogens.
		There are teratogen registries and all street drugs and medications have been classifed into categories A,B,C,D,X where A and B show no evidence of risk and B, C, and X show evidence of risk in increasing certainty.
	www.carolguze.com /oldsite/442teratogens.htm (2360 words)

	Natural Teratogens Page
		The following picture depicts a cyclopic lamb that was born from a ewe who had eaten skunk cabbage during her pregnancy.
		This is some of the first evidence giving scientists a possible cause for the limb anomalies that have been seen in frogs in recent years.
		A single dose of 360 rads before the 14th week of gestation was enough to kill a fetus.
	www.teratology.org /jfs/NaturalTeratogens.html (617 words)

	Teratogens, Drug (Pregnancy Drug Dangers) Medical Reference Medical Encyclopedia Information
		A teratogen is an agent that can disturb the development of the embryo or fetus.
		Teratogens can halt the pregnancy or, alternatively, permit the pregnancy to proceed but produce a congenital malformation (a birth defect).
		The following list is confined to drugs that have been proved to be capable of acting as teratogens and so are clear and present dangers during pregnancy.
	www.medicineonline.com /reference/Health/Medicine/Basic_Sciences/Anatomy/info/Teratogens-Drug-Pregnancy-Drug-Dangers (239 words)

	Glutathione for a Healthier Pregnancy - free article courtesy of ArticleCity.com
		Most substances or factors which cause birth defects (teratogens) are known to exert their embryotoxic effects because they cause oxidative stress.
		In the early embryonic stages, the fetus is sensitive to the toxic and teratogenic effects of chemicals, whereas it is sensitive to carcinogenic effects during late fetal stages.
		Environmental and lifestyle factors are known to cause oxidative stress and lower glutathione levels - resulting in birth defects, abortion and miscarriages in pregnancy.
	www.articlecity.com /articles/health/article_448.shtml (688 words)

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