Teratogens Flashcards
Infection may be acquired through:
- venereal transmission
- respiratory spread
- contact with infected blood products
- cat litter or uncooked meat
Infections acquired through venereal transmission (that are teratogens)
- syphilis
- gonorrhea
- herpes virus
- cytomegalovirus (CMV)
- HIV
Infections acquired through respiratory spread (that are teratogens)
- rubella
- varicella
- coxsackie
- parvovirus
Infections acquired through contact with infected blood products (that are teratogens)
- HIV
- hepatitis
- malaria
Infections acquired through cat litter or uncooked meat (that are teratogens)
- toxoplasmosis
Classic teratogenic gestational period
- days 31-71 (7-10 weeks from LMP)
- During organogenesis (organs are forming)
- Most women do not yet know that they are pregnant!
Timing of infection affects severity
- extremely early infections (before pregnancy is recognized) lead to embryonic death and resorption
- spontaneous abortion and stillbirth (SAB) infection in recognized pregnancy
- prematurity 24-37 weeks after LMP (usually infection in 3rd trimester) - IUGR and low birth weight
- congenital disease - at delivery or later on
General signs of infection after delivery
- purpura (red rash)
- jaundice (yellow-ish)
- hepatosplemomegaly (enlarged liver & spleen)
- pneumonitis (inflammation of lungs)
- meningoencephalitis (inflammation of brain)
Women should ideally have preconception screening for:
- rubella (immunization should be done, some batches of rubella vaccine were no good)
- toxoplasmosis (if you have a cat or eat rare meat)
- cytomegalovirus (if you are a healthcare worker…CMV is excreted in urine)
Types of antibodies measured
- IgG (antibody associated with lifelong immunity, starts 3-4 weeks after IgM)
- IgM (initial antibody formed following viral infection, goes away after 6 months)
Fetal interpretation of infection (IgG & IgA transplancental movement)
Since IgG is a small molecule it can pass transplacentally to fetus – therefore +IgG in cord blood can be maternal
IgM is too large to pass transplacentally – therefore, if the cord blood is +IgM for a specific illness, the fetus has been infected
Cytomegalovirus (CMV)
- High risk of intellectual disability/dev delay
- IUGR
- pneumonia
- hepatosplenomegaly
- thrombocytopenia
- microcephaly
- deafness
- optic nerve atrophy
- brain calcifications
- Ultrasound: echogenic bowel, fetal ascites, hepatic calcifications
- Rarely diagnosed during pregnancy because asymptomatic (10% of women have mono-like symptoms)
- Virus most commonly isolated in urine
- No treatment available for affected mother and child
- Can be sexually transmitted and therefore can be in vagina and passed to baby
Herpes (DNA Virus)
- no obvious malformations
- risk for CNS malformations
- no curative treatment
- primary maternal infection causes the greatest risk in early pregnancy and near term
- infection does not confer immunity
- there are 2 types of herpes: type 2 (genital form) causes the problem
- Virus in vagina and passed to baby is a problem, therefore do C-section when active infection
Varicella Zoster (DNA Virus)
- chicken pox
- 10-21 day incubation period, most contagious before breaking out
- Can be transmitted transplacentally at any time during pregnancy (even before blister – most infectious)
- 3% risk obvious abnormalities: scarring of skin, limb hypoplasia, microcephaly, cataracts, blindness, neonatal chicken pox,
- possible CHD (would need perfect exposure timing)
Human Parvovirus B19
- Classic rash – ‘slapped cheek’ and fever
- In adults it can cause acute polyarthalgia syndrome of hands, wrists, knees
- 10% risk of death any gestational age, but worst at 10-20 weeks
- Causes severe anemia – CHF – death (breaks down bone marrow)
- No risk for congenital anomaly even if exposure during 1st trimester
- IgM will be + in 90% of cases by 3rd day after symptoms appear
