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Common Teratogens

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Common Teratogens and Their Effects
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Page 1: Common Teratogens

Common Teratogens and Their Effects

Page 2: Common Teratogens

What is a teratogen?

Is any factor, chemical or physical, that adversely affects the fertilized ovum, embryo or fetus.

Is any agent that can induce or increase the incidence of a congenital malformation.

Page 3: Common Teratogens

What is teratology?

is the study of abnormal development in embryos and the causes of congenital malformations or birth defects

Page 4: Common Teratogens

Effects of teratogens on the fetus

Factors that influence the amount of damage a teratogen can cause:

Strength of teratogens (ex: radiation)Timing of the teratogenic insultDetermining the effects of a teratogen

Page 5: Common Teratogens

Teratogenic Maternal Infections

TORCH:ToxoplasmosisRubellaCytomegalovirusHerpes simplex virus

Note: some sources identify the O with “other infections”, which include syphilis, HBV, and HIV.

Page 6: Common Teratogens

Toxoplasmosis

A protozoan infection, is spread most commonly through contact with uncooked meat, although it may also be contracted through handling cat stool in soil or cat litter.

If the infection crosses the placenta, the infant may be born with CNS damage, hydrocephalus, microcephaly, intracerebral calcification, & retinal deformities.

Pyrimethamine, an antifolic acid drug and not administered in early pregnancy

Page 7: Common Teratogens

Rubella

Fetal damage from maternal infection with rubella (german measles) icludes deafness, mental and motor changes, cataracts, cardiac defects(most commonly patent ductus arteriosus & pulmonary stenosis), reatrded intrauterine growth(small for gestational age), thrombocytopenic purpura, & dental & facila clefts, such as cleft lip & palate (Lee & Bowden, 200)

Page 8: Common Teratogens

A women who is not immunized before pregnancy cannot be immunized during pregnancy.

After a rubella immunization, a woman is advised not to become pregnant for 3 months until the rubella virus is no longer active.

All women w/ low rubella titers should be immunized to provide protection against rubella in future pregnancies

Page 9: Common Teratogens

Cytomegalovirus (CMV) A member of herpes virus family Transmitted by droplet infection from person to

person. If a woman acquires primary CMV infection during

pregnancy and the virus crosses the placenta, congenital CMV infection can occur.

Infant may be born w/ severely neurologically challenged, w/ eye damage, deafness, or chronic liver disease.

Child’s skin may be covered w/ large petechiae (“blueberry-muffin” lesions)

Page 10: Common Teratogens

Herpes Simplex Virus (Genital Herpes Infection)

The virus spreads into the bloodstream (viremia) and crosses the placenta to the fetus.

1st trimester – congenital anomalities or spontaneous miscarriage may occur.

2nd or 3rd – high incidence of premature birth, intrauterine growth retariodation, & continuing infection of the newborn birth.

Intravenous or oral acyclovir (Zorivax) can be administered to women during preganancy (Karch, 2001).

Page 11: Common Teratogens

Other Viral Diseases

Syphilis – sexually transmitted infection Lyme Disease – a multisystem disease caused by

the spiochete Borrelia Burgdorferi, is spread by the bite of a deer tick.

Infection that cause illness at birth - gonorrhea, candidiasis, chlamydia, stretococcus B, and hepatitis B infections

Page 12: Common Teratogens

Potential Teratogenicity of Vaccines

Live virus vaccines such as measles, mumps, rubella and poliomyelitis (sabin type), are contraindicated during pregnancy because they may transmit the viral infecton to the fetus.

Page 13: Common Teratogens

Teratogenicity of Drugs

2 principles related to drug intake during pregnancy: Any drug or herbal supplement, under certain

circumstances, may be detrimental to fetal welfare. Therefore, during pregnancy, women should not take any drug or supplement not specifically prescribed by their physician or nurse midwife.

A woman of childbearing age and ability should take no drugs other than those prescribed by the physician or nurse midwife to avoid exposure to a drug should she become pregnant.

Page 14: Common Teratogens

Teratogenicity of Alcohol(internet)

Alcohol is a common drug abused by women of childbearing age. Infants born to alcoholic mothers demonstrate prenatal and postnatal growth deficiency, mental retardation, and other malformations.

There are subtle but classical facial features associated with fetal alcohol syndrome including short palpebral fissures, maxillary hypoplasia, a smooth philtrum, and congenital heart disease.

Even moderate alcohol consumption consisting of 2 to 3 oz. of hard liquor per day may produce the fetal alcohol effects.

Binge drinking also likely has a harmful effect on embryonic brain developments at all times of gestation.

Page 15: Common Teratogens

Teratogenicity of Cigarettes

Growth retardation Sudden infant death syndrome (Pollack, 2001) Low birthweight in infants of smoking mothers

results from vasoconstriction of the uterine vessels, an effect of nicotine that limits the blood supply to the fetus.

Inhaled carbon monoxide Reducing the number of cigarettes smoked per

day should help diminish adverse effects on the fetus.

Page 16: Common Teratogens

Environmental Teratogens

Metal and chemical hazards – ex: pesticides & carbon monoxide

Radiation – has been proven to be a potent teratogen to unborn children because of high proportion of rapidly growing cells present.

Hyperthermia & Hypothermia – (hyper) may be detrimental to growth because it interferes with cell metabolism, (hypo) the effects is not well known.

Page 17: Common Teratogens

Teratogenicity of Maternal Stress

Emotionally disturbed pregnancy, once filled with anxiety and worry beyond the usual amount could produce physiologic changes through its effect on the sympathetic division of the autonomic nervous system.

Primary changes includes increase in heart rate, constriction of the peripheral blood vessels, a decrease in gastrointestinal motility, & dilation of coronary blood vessels (the fight-or-flight syndrome)

The constriction of uterine vessels could interfere with the blood and nutrient supply to the fetus.


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