– IS ANY FACTOR, CHEMICAL OR PHYSICAL, THAT ADVERSELY AFFECTS THE FERTILIZED OVUM, EMBRYO, OR FETUS. EFFECTS OF TERATOGENS ON A FETUS:
1) depends on the:
a) strength of the teratogen
ex. Radiation – in small amount sun rays it causes no damage, but in large amount like in cancer treatment, serious fetal defects or death can occur. b) timing of teratogen
before implantation = zygote is aborted or is unaffected organogenesis – vulnerable to injury
Last trimester – decreased harm (except syphilis and toxoplasmosis these infections can cause abnormalities in organs that were originally formed normally). c) teratogens affinity for specific tissue
Lead – attacks and disables nervous tissue.
Thalidomide – limb defect
Tetracycline – tooth enamel deficiencies and possibly long bone deformities. Rubella virus – eyes (blind), ears (deaf), heart and brain.
TERATOGENIC MATERNAL INFECTIONS
hep B virus
HERPES SIMPLEX VIRUS
o Is a protozoan infection
o Spread commonly through contact of uncooked meat, although it may also be contracted w/ through handling cat stool in soil or cat litter o A woman experiences no symptoms of the disease, except a few days of malaise and posterior cervical lymphadenopathy o The infection crosses the placenta
o Infant may new born w/ CNS damage, hydrocephalus, microcephaly, intracerebral calcification, and retinal deformities. o 1:900 pregnancies
o Dx: serum analysis during pregnancy
Sulfonamides, but fetal anomaly is uncertain, and sulfa may increased bilirubin levels in newborn Pyrimethamine, anantiprotozoal agent may also be used, but this is antifolic acid drug, so it is administered w/ caution in early pregnancy to prevent reducing folic acid levels....