9.3 Tetragens

a. A teratogen is an agent or factor that causes the production of physical defects in the developing fetus.

b. Many drugs are known to have teratogenic effects on the fetus if taken during pregnancy. Drugs are the most widely recognized cause of structural defects in the developing fetus. Patients need to be cautioned about taking any medication without a physician's approval. Over-the-counter medicines such as nose drops, cold remedies, and sleep medications may cause problems.

(1) Examples of known effects:

(a) Physical abnormalities - no arms or legs.
(b) Hemorrhage or jaundice.
(c) Neurologic symptoms.
(d) Abnormal dental pigmentation.
(e) Addiction.
(f) Vaginal malignancy or altered sperm causing infertility.

(2) The effects of many drugs may not be known until later years during the growth and development of the child.

c. Teratogenic drug examples.

(1) Thalidomide-used in England in the 1950's and 1960's as a sedative.
(2) Phenytoin (Dilantin)®-used for seizures.
(3) Methotrexate®-used to treat neoplastic diseases.
(4) Diethylstilbestrol®-used for vasomotor symptoms during menopause.
(5) Accutane®--used to treat cystic acne.

d. Teratogenic viruses and parasites.

(1) Herpes simplex.
(2) Rubella (German measles).
(3) Toxoplasmosis. This is transmitted by cat feces and raw meat.
(4) Influenza or viral infections in the early weeks of pregnancy.

e. Other teratogenic conditions.

(1) Hyperthermia.
(2) Maternal disease (diabetes).
(3) Maternal malnutrition.
(4) X-rays should be avoided. Radiation from the x-rays can cause deformity of the fetuses if exposed in the first trimester.
(5) Environmental pollutants.
(6) Lead.
(7) Increase in maternal age.
(8) Tobacco and alcohol.

f. Patients need to be reminded of the potential dangers of the things they may do or take. The worst damage to the fetus is done in the early weeks of the pregnancy before she even knows she is pregnant.



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