Repro - Embryology (Teratogens)

Question 1

During what time frame of pregnancy are embryos most susceptible to teratogens? What is time period called?

Answer 1

Most susceptible in 3rd-8th weeks (embryonic period - organogenesis) of pregnancy

Question 2

What are the time frames that generally distinguish the extent of teratogenic effects? What are outcomes of teratogens during each of these time frames?

Answer 2

Before week 3: all-or-none effects; After week 8: growth and function affect

Question 3

What is the effect of ACE inhibitors on a fetus?

Answer 3

Renal damage

Question 4

What are 2 effects of Alkylating agents on a fetus?

Answer 4

Absence of digits, multiple anomalies

Question 5

What is the effect of Aminoglycosides on a fetus?

Answer 5

CN VIII toxicity; Think: “A MEAN GUY hit the baby in the ear”

Question 6

What are 5 effects of Carbamazepine on a fetus?

Answer 6

Neural tube defects, craniofacial defects, fingernail hypoplasia, developmental delay, IUGR (intrauterine growth restriction)

Question 7

What are 2 effects of Diethylstilbestrol (DES) on a fetus?

Answer 7

Vaginal clear cell adenocarcinoma, Congenital Mullerian anomalies

Question 8

What is the effect of Folate antagonists on a fetus?

Answer 8

Neural tube defects

Question 9

What is the effect of Lithium on a fetus?

Answer 9

Ebstein anomaly (atrialized right ventricle)

Question 10

What is the effect of Methimazole on a fetus?

Answer 10

Aplasia cutis congenita

Question 11

What is the effect of Phenytoin on a fetus? What 6 symptoms define this effect?

Answer 11

Fetal hydantoin syndrome: microcephaly, dysmorphic craniofacial features, hypoplastic nails and distal phalanges, cardiac defects, IUGR, intellectual disability

Question 12

What is the effect of Tetracyclines on a fetus?

Answer 12

Discolored teeth; Think: “TEETHracyclines”

Question 13

What is the effect of Thalidomide on a fetus? Give 2 examples of this effect.

Answer 13

Limb defects (phocomelia, micromelia - “flipper” limbs)

Question 14

What is the effect of Valproate on a fetus, and why?

Answer 14

Inhibition of maternal folate absorption => neural tube defects; Think: “valproATE inhibits folATE absorption”

Question 15

What are 4 effects of Warfarin on a fetus?

Answer 15

Bone deformities, fetal hemorrhage, abortion, ophthalmologic abnormalities; Think: “do not wage WARFARe on the baby; keep it HEPpy with HEParin (does not cross placenta)”

Question 16

Give 13 examples of medications that act as teratogens.

Answer 16

(1) ACE inhibitors (2) Akylating agents (3) Aminoglycosides (4) Carbamazepine (5) Diethylstilbestrol (DES) (6) Folate antagonists (7) Lithium (8) Methimazole (9) Phenytoin (10) Tetracyclines (11) Thalidomide (12) Valproate (13) Warfarin

Question 17

Name 3 forms of substance abuse that can have teratogenic effects.

Answer 17

(1) Alcohol (2) Cocaine (3) Smoking (nicotine, CO)

Question 18

What are 2 effects of alcohol on a fetus? What is the name of the related condition?

Answer 18

Common cause of birth defects and intellectual disability; Fetal alcohol syndrome

Question 19

What are 2 effects of cocaine on a fetus? What obstetric complication is associated with cocaine?

Answer 19

Abnormal fetal growth and fetal addiction; placental abruption

Question 20

Of what is smoking (nicotine, CO) a leading cause in fetuses/newborns, and where? What are 4 other effects of smoking on a fetus?

Answer 20

A leading cause of low birth weight in developed countries; associated with preterm labor, placental problems, IUGR, ADHD

Question 21

Besides medications and substance abuse, what are 4 other examples of teratogens?

Answer 21

(1) Iodine (lack or excess) (2) Maternal diabetes (3) Vitamin A (excess) (4) X-rays

Question 22

What are the effects of Iodine (lack or excess) on a fetus?

Answer 22

Congenital goiter or hypothyroidism (cretinism)

Question 23

What are 3 effects of Maternal diabetes on a fetus?

Answer 23

Caudal regression syndrome (anal atresia to sirenomelia), congenital heart defects, neural tube defects

Question 24

What 2 risks are high for fetuses experiencing Vitamin A excess?

Answer 24

Extremely high risks for spontaneous abortions and birth defects (cleft palate, cardiac abnormalities)

Question 25

What are 2 effects of X-rays on a fetus?

Answer 25

Microcephaly, Intellectual disability

Question 26

What is important to consider about microbiology and teratogens?

Answer 26

Fetal infections and certain antibiotics can also cause congenital malformations (see the Microbiology chapter).