🤰 Medication Use in Pregnancy — Reference
Reference on medication use in pregnancy: the withdrawn FDA letter categories, the PLLR labelling rule, prescribing principles and authoritative resources. Browser-side.
The old letter categories were misread as a risk ladder and are historical only.
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When to use
Understand the labelling framework and where to find evidence-based per-drug guidance — not a per-drug rating itself.
How it works
PLLR (2015) replaced A/B/C/D/X letters with narrative sections: pregnancy, lactation, and females/males of reproductive potential.
Key points
- The old letter categories were misread as a risk ladder and are historical only.
- Weigh the risk of untreated maternal disease against the drug risk.
- Prefer well-evidenced agents at the lowest effective dose; organogenesis (≈ 3–8 weeks) is most sensitive.
- Consult MotherToBaby/LactMed and the latest label for specific drugs.
References
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| View | Former FDA categories (withdrawn) |
|---|
→ReferenceFormer FDA pregnancy categories A/B/C/D/X (withdrawn 2015)
- A：Controlled studies show no fetal risk (e.g. appropriate folate, levothyroxine)
- B：No risk in animals but no human controlled data, or animal risk not confirmed in humans
- C：Adverse in animals / no human controlled data → weigh risk vs benefit (most drugs were here)
| View | Authoritative resources |
|---|
→ReferenceAuthoritative resources
- MotherToBaby：mothertobaby.org — evidence-based exposure counselling
- LactMed：Drugs and Lactation Database
- FDA PLLR：US-label pregnancy/lactation narrative information
Frequently asked questions
- What is Medication Use in Pregnancy — Reference?
- Reference on medication use in pregnancy: the withdrawn FDA letter categories, the PLLR labelling rule, prescribing principles and authoritative resources. Browser-side.
- How is Medication Use in Pregnancy — Reference calculated? What is the core formula?
- PLLR (2015) replaced A/B/C/D/X letters with narrative sections: pregnancy, lactation, and females/males of reproductive potential.
- When is Medication Use in Pregnancy — Reference used?
- Understand the labelling framework and where to find evidence-based per-drug guidance — not a per-drug rating itself.
- What are the key clinical points for Medication Use in Pregnancy — Reference?
- The old letter categories were misread as a risk ladder and are historical only. Weigh the risk of untreated maternal disease against the drug risk. Prefer well-evidenced agents at the lowest effective dose; organogenesis (≈ 3–8 weeks) is most sensitive. Consult MotherToBaby/LactMed and the latest label for specific drugs.
- What are the limits and cautions when using Medication Use in Pregnancy — Reference?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Medication Use in Pregnancy — Reference calculated in practice? Can you show a worked example?
- Inputs: View Former FDA categories (withdrawn) → Result: Reference Former FDA pregnancy categories A/B/C/D/X (withdrawn 2015)（A: Controlled studies show no fetal risk (e.g. appropriate folate, levothyroxine), B: No risk in animals but no human controlled data, or animal risk not confirmed in humans, C: Adverse in animals / no human controlled data → weigh risk vs benefit (most drugs were here)） Inputs: View Authoritative resources → Result: Reference Authoritative resources（MotherToBaby: mothertobaby.org — evidence-based exposure counselling, LactMed: Drugs and Lactation Database, FDA PLLR: US-label pregnancy/lactation narrative information）