ABGC Boards: Teratogens

When is the all or nothing period?

first 2 weeks following fertilization

What is the all or nothing period?

preimplantation period where the teratogen will either result in miscarriage or nothing will happen

What are examples of substances that are teratogenic?

medications, recreational drugs, tobacco, alcohol

What are examples of physical agents that can be teratogenic?

hyperthermia, radiation

What are examples of infections exposures that can be teratogenic?

cmv, toxoplasmosis, parvovirus, herpes simplex virus, syphilis, varicella, rubella

What are examples of maternal health factors that can be teratogenic?

diabetes, pku, hypothyroidism

What are important factors in determining the possible effects of a teratogen?

dose and route, duration of exposure, timing of exposure

What birth defects are associated with smoking?

cleft lip/palate, gastroschisis, possible musculoskeletal defects

What pregnancy complications are associated with smoking?

stillbirth (50%), premature rupture of membranes, IUGR, placental abruption

What facial features are associated with fetal alcohol syndrome?

small head, small eye opening, flat midface, smooth philtrum, thin upper lip

What risks are present for alcohol consumption in the first trimester?

facial anomalies, major structural anomalies

What risks are present for alcohol consumption in the second trimester?

spontaneous abortion

What risks are present for alcohol consumption in the third trimester?

abnormal weight, length, brain growth

What features are associated with maternal anti-seizure medications?

neural tube defects, CHDs, skeletal anomalies, oral clefts

Which anti-convulsant has the greatest impact?

valproic acid

What birth defect resulted from thalidomide use?

limb reduction defects

What was thalidomide used to treat?

nausea

What is isotretinoin (Accutane) used to treat?

severe acne

What anomalies are associated with Accutane usage?

CNS malformations, ear anomalies, hydrocephalus, ID, heart defects, etc.

What features are associated with maternal SSRI usage?

neonatal jitteriness, irritability, persistent pulmonary hypertension

What is depression in pregnancy associated with?

pre-eclampsia, growth restriction, preterm birth

What is first trimester hyperglycemia associated with?

cardiac defects, neural tube defects, contractures, clefting, caudal regression

What is second trimester hyperglycemia associated with?

fetal hyperglycemia, hyperinsulinemia, macrosomia

What is hyperglycemia?

high blood sugar--maternal diabetes

What are ACE inhibitors used to treat?

hypertension

What are ACE inhibitors associated with?

renal anomalies, potter sequence, IUGR

When is the critical period for ACE inhibitors?

2nd and 3rd trimester

What is lithium exposure associated with?

ebstein anomaly

What is lithium used to treat?

bipolar disorder

What is maternal PKU associated with?

microcephaly, ID, heart defects

What is maternal mercury exposure associated with?

minimata disease

What is maternal radiation exposure (>5 rrads) associated with?

fetal malignancy, miscarriage, IUGR, ID

Pregnant people with diabetes are at a ___x increased risk for birth defects.

3x

What is the most common congenital viral infection?

cytomegalovirus (CMV)

What features are associated with CMV?

IUGR, cerebral calcifications, hearing loss, microcephaly, echogenic bowel, hydrops, etc.

What is toxoplasmosis?

parasitic infection common in cats

What percentage of infants infected with toxoplasmosis are asymptomatic at birth?

90%

What features are associated with toxoplasmosis?

hydrocephalus, intracranial calcifications, chorioretinitis (vision loss)

What can parvovirus result in during pregnancy?

fetal anemia and hydrops (though rare)

What is syphilis exposure associated with?

snuffles, hutchinson teeth, saber shins, saddle nose

What is varicella exposure associated with?

skin scarring, hypoplastic extremities, ventriculomegaly

What is rubella exposure associated with?

deafness, cataracts, CHD, blueberry muffin rash, salt and pepper retinopathy

What is herpes exposure during birth associated with?

severe CNS and organ damage

What does TORCH stand for?

toxoplasmosis, other (varicella, syphilis, parvo), rubella, cmv, herpes

What tests can be used to assess for infection?

amniocentesis or maternal serum studies

What is the benefit of amniocentesis to assess infection?

definitely tells us if the fetus has been exposed

What is the benefit of maternal serum studies to assess infection/exposure?

non-invase, no risk

What is measured in maternal serum studies?

IgM and IgG

What does elevated IgM indicate?

recent infection, could have been during pregnancy

What does elevated IgG indicate?

past exposure, likely from before pregnancy

How can you remember IgG?

G = ghost from the past

If both IgM and IgG are high, what testing should be completed?

avidity testing

What does avidity testing measure?

how strongly IgG antibodies bind to the antigen

What does high avidity indicate?

infection occurred more than 3-4 months ago (higher scores = stronger bond = antibodies present longer)

What does low avidity indicate?

infection occurred less than 3-4 months ago

What qualifies as hyperthermia exposure?

>102F for 24+ hours

What findings are associated with hyperthermia?

growth deficiency, CNS defects, ONTD, midface hypoplasia, etc.

What is the critical period for hyperthermia exposure?

4-14 weeks post fertilization

What is tetracycline used for?

acne, antibiotic

What features are associated with tetracycline exposure?

discoloration and malformation of primary teeth

What is the critical period for tetracycline exposure?

beyond 4th month

What features are associated with heroin exposure?

no concern for fetal malformations, risk for neonatal withdrawal

What are the possible teratogenic effects of cocaine exposure?

prematurity, placental abruption, IUGR, etc.

What is the critical period for palate formation and smoking exposure?

8-11 weeks gestation

What is the critical period for growth and smoking exposure?

last 4 months of pregnancy

What is the critical period for alcohol exposure?

organogenesis to term (8 weeks to term)