Drugs in Pregnancy

The Therapeutic Goods Administration classifies drugs for suitability in pregnancy based on the potential of a drug to cause:

• Birth defects
• Detrimental effects at birth
• Problems in later life

The classification system is:

• Valid only for the dose and route of administration listed
  • Does not apply in overdose
• Not hierarchical
  • 'B' drugs are not safer than 'C' drugs

Categories

• Category A
  Taken by large number of women without detrimental effects.

• Category B
  Taken by a limited number of women without detrimental effect. Subclassified by results from animal studies into:
  • Category B1
    Animal studies show no evidence of detrimental effect to the foetus.
  • Category B2
    Animal studies are inadequate or lacking, but available data shows no evidence of detrimental effect to the foetus.
  • Category B3
    Animal studies show evidence of foetal damage, but the significance of this in humans is unknown.

• Category C
  • Drugs which have caused (or a suspected to cause) detrimental foetal effects, but without malformations
  • These effects may be reversible

• Category D
  • Drugs which have caused (or are suspected to cause) an increased incidence of foetal malformations or damage
  • May also have detrimental effects

• Category X
  • Drugs which have a high risk of causing permanent damage
  • Should not be used in pregnancy, or when pregnancy is possible

References

1. Australian categorisation system for prescribing medicines in pregnancy. Therapeutic Goods Administration.