Common teratogens and drug categories – USMLE CK Exam

by / Friday, 16 July 2010 / Published in OB/GYN


Category Description
A Medication has not shown an increase in risk for birth defects in human studies.
B Animal studies have not demonstrated a risk, and there are no adequate studies in humans, OR animal studies have shown a risk, but the risk has not been seen in humans.
C Animal studies have shown adverse effects, but no studies are available in humans, OR studies in humans and animals are not available.
D Medications are associated with birth defects in humans; however, potential benefits in rare cases may outweigh their known risks.
X Medications are contraindicated in human pregnancy because of known fetal abnormalities that have been demonstrated in both human and animal studies.


Drug Birth Defect
Lithium Ebstein’s anomaly (single-chambered right side of heart).


Neural tube defects.
Retinoid Acid CNS defects, craniofacial defects, cardiovascular defects.
ACE Inhibitors Decreased skull ossification, renal tubule dysgenesis, renal failure in neonate.
Oral hypoglycemics Neonatal hypoglycemia
Warfarin CNS & Skeletal defects
NSAIDs Necrotizing enterocolitis, constriction of ductus arteriosis.

2 Responses to “Common teratogens and drug categories – USMLE CK Exam”

  1. Do we need to know more teratogens other than those mentioned in this post?

    • Dr. Paul Ciurysek, M.D. says : Reply

      There always seems to be some sort of teratogen on the USMLE that we’ve never seen or heard of, but for the most part this is the highest yield and the most commonly tested material.

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