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Genetic Counseling > Teratogens > Flashcards

Teratogens Flashcards

1
Q

What is the background risk for birth defects during pregnancy?

A

3-5%

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2
Q

What percentage of birth defects are caused by teratogenic exposure?

A

~10%

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3
Q

What are some characteristics of a teratogen?

A
  1. Increased occurence of an abnormal effect
  2. dose-response relationship (often w/threshold effect)
  3. period of greatest sensitivity
  4. established mechanism of action
  5. plausible biological explanation
  6. genetic basis of susceptibililty
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4
Q

When is the “all or none” period?

A

0-2 weeks conceptual age

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5
Q

When is the period of greatest sensitivity for NTD’s? (when is the neural tube closing?)

A

2-4 weeks conceptual age (beware of fever/high temps, hot tubs, folic acid antagonists)

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6
Q

When is the period of greatest sensitivity for organogenesis?

A

3-8 weeks conceptual age (exposures potentially result in major malformations, growth retardation, IQ deficits)

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7
Q

In what trimester does the fetus grow most in length? (crown-rump)

A

2nd trimester (growth, maturation, and neural development of the fetus)

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8
Q

In what trimester does the fetus gain most weight?

A

3rd trimester (21-38 weeks conceptual age–> growth maturation, and neural development)

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9
Q

When is the “embryonic period”?

A

Weeks 3-8 conceptual age
(also the period of organogenesis)
(Weeks 3/4 are when gastrulation, neurulation, and development of the embryonic axis occur)

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10
Q

What happens during the 1st week post-conception? (CA 0-7 days)

A

Initial cleavage of the zygote, transport to oviduct, implantation

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11
Q

What happens during the 2nd week post-conception (CA 8-14 days)

A

Proliferation of the trophoblast, placental development

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12
Q

When does cardiac formation occur?

A

Weeks 3-8 conceptual age

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13
Q

When does limb development occur?

A

Weeks 4-9

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14
Q

True or False: “No teratogen causes birth defects in 100% of exposed fetuses”

A

True– example of the “genetic basis of susceptibility” characteristic of teratogens

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15
Q

Name the teratogen:
An antihistamine found to be an excellent sedative; used to treat nausea in pregnancy; later used in treatment of leprosy (Brazil); most recently shown to be effective in treating specific cancers (ex: melanoma).

A

Thalidomide

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16
Q

Name some of the characteristics of Thalidomide embryopathy

A

inhibits normal function of CRBN protein in limb development–> results in limb malformations (79-89%), may also see absent ears, microtia, defects of the genitals, kidneys, gut, neurological manifestations. Period of greatest sensitivity: days 20-34 conceptual age (~3-5 weeks)

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17
Q

Is an FDA pregnancy category A drug okay to take during pregnancy?

A

Apparently yes “Adequate, well-controlled human studies have shown no risk to the fetus.”

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18
Q

What does it mean if the FDA has placed a drug in pregnancy category X?

A

“Studies in animals or humans show risk AND the risks clearly outweigh the potential benefits” This drug is clearly contraindicated in pregnancy.

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19
Q

Where can you find MSDS sheets available to gather information about potential teratogenic effects of chemicals encountered in a lab setting?

A

OSHA

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20
Q

Are babies exposed to a higher concentration of maternal medications during pregnancy or during lactation?

A

Pregnancy

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21
Q

True or false: Medications have a shorter half-life in infants than they do in mothers.

A

False– half-lives of medications are longer in infants, because their livers metabolize more slowly

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22
Q

What does TORCH stand for?

A 
T- Toxoplasmosis
O- Other (Syphillis, Varicella)
R- Rubella
C- CMV
H- Herpes
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23
Q

What percentage of maternal toxoplasmosis infections result in congenital toxoplasmosis cases?

A

30%

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24
Q

Risks associated with congenital toxoplasmosis?

A

Chorioretinitis, hydrocephalus, intracranial calcifications.
85% of infected infants are asymptomatic at birth, but 90% will develop symptoms later which may include:
ocular lesions, jaundice, HSM, lymphadenopathy, microcephaly, HL, ID, cerebral palsy, seizures…
Only 10% are totally asymptomatic.

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25
Q

Can women with toxoplasmosis safely breastfeed?

A

Why yes; yes they can.

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26
Q

Risks associated with untreated maternal syphilis?

A

2/3 of exposed fetuses will be affected.

-Death, stillbirth, or miscarriage risks are very significant if untreated.

-Most that are liveborn are asymptomatic, 66% symptomatic by 8 weeks, almost 100% symptomatic by 3 months with:
bony abnormalities (ex: saber shins), HSM, petechiae, skin lesions, anemia, jaundice, pseudoparalysis, persistent rhinitis (irritation of mucous membrane inside nose). 
Later on (>2 years) may see:
frontal bossing, palate deformation, dental abnormalities, saddle nose, sensorineural deafness, DD
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27
Q

Can women with syphilis safely breastfeed?

A

Yep– as long as there are no lesions on the breast or nipple. Also delay BF until 24 hours post initiation of treatment.

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28
Q

What is assocaited with congenital rubella syndrome?

A

60% deafness, ~50% cataracts, congenital heart defects (VSDs, PDA, PS, CoA), microcephaly and MR (10-20%), encephalitis, HSM, thrombocytopenia

(most women were vaccinated in childhood)

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29
Q

What is associated with congenital CMV?

A

microcephaly, ID, sensorineural HL, chorioretinitis, seizures, intracranial calcifications, HSM, thrombocytopenia, petechiae, IUGR, dental defects, motor defects

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30
Q

What percentage of adults in the US have been infected with CMV?

A

50-80% (mostly asymptomatic)

but the risk for congenital CMV is only if it is a primary or recurrent infection

31
Q

What percentage of live born babies have congenital CMV?

A

1-3% (it is more common than FAS, Down syndrome, and spina bifida… however:)
90% born asymptomatic– and only 20% of that 90% develop symptoms later; 80% remain asymptomatic

32
Q

Can women with CMV safely breastfeed?

A

Yep, but safest if the baby is full term!

may cause late-onset sepsis like syndrome in premature infants, but benefits still thought to outweigh risks

33
Q

What is herpes simplex virus II (HSV II)?

A

Genital herpes

34
Q

When might HSV II (herpes simplex virus II) be transmitted to an infected fetus/infant?

A

5% transmitted in utero
85-90% cases transmitted intrapartum (during birth)
5-10% transmitted postnatally

35
Q

What is the risk of neonatal HSV infection after vaginal delivery?

A

33-50%

36
Q

What are the findings associated with a congenital, INTRAUTERINE HSV II infection?

A

skin vesicles/scarring, chorioretinitis, micropthalmia, cataracts, microcephaly, intracranial calcifications, seizures, encephalomalacia, encephalitis, growth retardation, psychomotor development delays

37
Q

What are the findings associated with an intrapartum or postnatal HSV II infection?

A

skin, eye, mouth lesions and/or HSV encphalitis
OR
disseminated HSV which manifests as severe multi-organ dysfunction (CNS, liver, lung, brain, adrenals) + skin, eye, mouth lesions

38
Q

Can a mother with HSV II breastfeed?

A

YES- as long as she does not have an active HSV lesion on her breast.

39
Q

How can TORCH testing be done?

A

Can do TORCH titers on Mom’s blood.. if positive, can do PCR on AF to look for transmission to fetus.

40
Q

What are the risks associated with maternal PKU?

A 
"phenocopy of FAS"
DD- 92%
microcephaly- 72%
IUGR- 40%
cardiac defect- 12-15%
postnatal growth retardation- 51%
SAB: 24%
41
Q

Can a mother with PKU breastfeed an unaffected (carrier) child?

A

Yes. (but a child with PKY may not be able to breastfeed)

42
Q

What are the risks associated with diabetic embryopathy?

A

LOTS- preterm birth, macrosomia, congenital anomalies, cardiovascular defects (ex: hypoplastic left heart), organomegaly, skeletal defects, NTD’s, caudal regression, respiratory, hematologic, metabolic, GI, and renal problems… VACTERL

43
Q

What does VACTERL stand for and what maternal condition is it associated with?

A 
Associated with uncontrolled maternal diabetes:
V-Vertebral abnormalities
A-Anal atresia
C-Cardiac abnormalities
T- Tracheo-esophageal fistula
R- Renal abnormalities
L- Limb defects
44
Q

Can a mother with diabetes breast feed?

A

Sure can.

45
Q

What are the risks associated with maternal alcohol use?

A

FAS- a spectrum that may include– low birth weight, CL +/- CP, ID, short palpebral fissures, microcephaly, long smooth philtrum, growth deficiencies, pectus ex/cari, contractures, hypospadias, renal defects ear abnormalities, congenital heart disease (ex: ASD, VSD, TOF)

46
Q

Is there a known safe amount of alcohol during pregnancy?

A

NO- but there is a known association between increased exposure=increased likelihood and severity affected

47
Q

Can you drink and breastfeed?

A

Not recommended– milk alcohol level is similar to blood alcohol level. Wait until you are no longer ‘drunk’ or 8-16 hours after rinking– consider formula feeding if you will be drinking moderately-regularly.

48
Q

What percentage of pregnancy women report using street drugs?

A

4%!

49
Q

What percentage of women report using cocaine in pregnancy?

A

.4-31% depending on region and study.. Detroit was 31%.

50
Q

What are the risks of cocaine use during pregnancy?

A

premature delivery (50%) with increased risks for miscarriage and placental abruption

withdrawal in the fetus/infant (50%)

cerebrovascular events in fetus resulting in brain damage (30%)– may include seizures, apnea, tachycardia,etc.

growth restriction- (18%)

congenital anomalies- (7-26%)- may include limb amputation defects (vasoconstriction), CHD, intestinal defects, CL+/-CP

51
Q

Can you do cocaine and breastfeed?

A

Nope.

52
Q

What are the risks of taking isoretinoin (ex: accutane) during pregnancy?

A

CNS defects (ex:hydrocephalus), microtia, CP, hypertelorism, conotruncal cardiac malformations, TOF, thymic ectopia or hypo/aplasia, spina bifida, hypotonia, liver issues, anotia, triangular skull, micrognathia and small mouth, limb reduction defects….

**Category X- 10x risk of birth defects at 30-50%, critical period of exposure is 5-7 weeks!

53
Q

Has the iPLEDGE system (mandates 2 forms of birth control and monthly pregnancy tests for isoretinoin users) decreased adverse pregnancy outcomes associated with isoretinoin use?

A

Nope.

54
Q

What are some common AEDs?

A

Valproic acid, lithium, carbamazepine, phenobarbital, phenytoin, lamotrigine

55
Q

Which AEDs are associated with the greatest risks of birth defects?

A

Valproic acid and lithium (2-3x increased risk for birth defects…
2x increase for others like phenytoin, phenobarb, carbamazepine, etc.)

56
Q

When is the most critical period for adverse effects associated with AEDs in pregnancy?

A

1st trimester exposure

57
Q

What is the risk for NTD for woman taking AED?

A

1-2%

Because AED’s are folate antagonists (lamotrigine is the most associated)

58
Q

What AED is most associated with Ebstein’s anomaly (heart defect of the tricuspid valve)?

A

Lithium- 1/1000 risk for Ebstein’s anomaly.

59
Q

What are the features associated with “AED embryopathy”?

A

CL +/- CP, CHD, hypoplasia of midface and fingers, microcephaly, small body size, “doll like” facies with full cheeks.

Valproic acid carries the greatest risk for AED embryopathy at 5-9%

60
Q

How should a woman who takes AEDs be ideally managed before/during pregnancy?

A

DON’T STOP MEDS–> control of seizures and mood disorders is most important

  • use lowest effective dose
  • use only one drug if possible (rather than combos)
  • avoid valproic acid if possible (may need to switch meds)
  • Take increased folic acid (1-4 mg vs. general pop. .4 mg) prior to pregnancy and during the 1st trimester to decrease risk of NTD’s
61
Q

Can you take accutane and breastfeed?

A

Not recommended, because no studies exist.

62
Q

Can you take AEDs and breastfeed?

A

Yep– however, note that the AEDs ARE transmitted into milk– but no contraindication known.

63
Q

Is it okay to take antihypertensives in pregnancy?

A

Trick question- depends on the antihypertensive! (ACE inhhibitors are clearly contraindicated–>take a different one!)

64
Q

What risks are associated with maternal ACE inhibitor use?

A

In the 1st trimester:
2.7x increase for birth defects, especially CNS and cardiac anomalies

In the 2nd trimester:
affects KIDNEY development and fxn leading to characteristics similar to bilateral renal agenesis (BAD!)–> oligohydramnios, Potter facies/sequence, calvarial hypoplasia, IUGR, renal failure leading to fetal demise or neonatal death,

65
Q

Can you take ACE inhibitors and breastfeed?

A

You betcha. (does transmit to breast milk, but okay/not contraindicated).

66
Q

What are the risks associated with radiation exposure during pregnancy?

A

None associated with <1 rad

350-500 rad would be ex: targeted cancer treatment

67
Q

What is the risk for major congenital anomalies with maternal diabetes?

A

6-12% overall

*If glycosylated Hgb9.5%, 22% risk!**

–> VERY IMPORTANT TO CONTROL DM DURING PREGNANCY

68
Q

What does failure of the neural tube to close on the rostral end lead to?

A

Anencephaly

69
Q

How common is Rh incompatability in Caucasians?

A

10-15% incidence (most common)

For African Americans, 5-8%
For Asians, 1-2%

70
Q

If all else is unknown, what is the likelihood of a an Rh negative woman having an Rh positive fetus?

A

60%

71
Q

What are the risks associated with Rh incompatability?

A

If mom is negative and fetus is positive, risk for sensitization– mom produces D antibody that crosses placenta and causes erythoblastosis fetalis:
fetal red blood cell hemolysis leading to severe anemia–> fetal heart has to work harder to circulate oxygen to the fetus w/less RBC’s–> heart failure–> fetal hydrops–> demise

72
Q

How can you treat fetal anemia and hydrops resultant from Rh incompatability?

A

Can perform intrauterine fetal transfusion–> blood (RBCs) into umbilical cord of fetus will resolve fetal hydrops if caught early enough (has its own risks obviously)

Must repeat the IUT every few weeks until 34-36 weeks gestation. May also require transfusion at birth

Once it occurs once–> all future pregnancies will be affected by Rh isoimmunization

73
Q

What are some risks of neonatal lupus syndrome?

A

Maternal SLE antibodies cross placenta and attack fetus–> result in:

hematologic complications (ex: hemolytic anemia, leukopenia, thrombocytopenia)
skin lesions (gone at ~1 year of life)
heart defects (ex: congenital heart block- fibrosis of the AV node--> 1/3 children die in first 3 years of life, survivors require pacemakers)
74
Q

What is the recurrence risk for congenital heart block for a woman with SLE who has had a previous child with congenital heart block?

A

15%

Genetic Counseling (14 decks)

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