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Letrozole Pregnancy and Breastfeeding Warnings

Letrozole is also known as: Femara

Medically reviewed by Last updated on May 14, 2020.

Letrozole Pregnancy Warnings

Animal studies have revealed embryotoxicity, fetotoxicity, and teratogenicity with doses much smaller than the daily maximum recommended human dose on a mg/m2 basis. Adverse effects included increased embryo and fetal toxicity, pre- and post-implantation pregnancy loss and resorptions, fewer live fetuses, congenital malformations affecting the renal and skeletal systems, and decreased fertility including sexual inactivity in females, reproductive tract atrophy in males and females, and reductions in successful mating and pregnancy.

AU TGA pregnancy category D: Drugs which have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects. Accompanying texts should be consulted for further details.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D and X are being phased out.

Use is contraindicated.

AU TGA pregnancy category: D
US FDA pregnancy category: Not assigned.

Risk Summary: Based on postmarketing reports, findings from animal studies, and its mechanism of action, this drug can cause fetal harm and is contraindicated for use in pregnant women. In post-marketing reports, use of this drug during pregnancy resulted in spontaneous abortions and congenital birth defects; however, the data are insufficient to inform a drug-associated risk.

-Based on animal studies, this drug can harm a developing fetus.
-Advise females of reproductive potential to use effective contraception during therapy and for at least 3 weeks after.
-Females of reproductive potential should have a pregnancy test prior to starting therapy.

See references

Letrozole Breastfeeding Warnings

Use is contraindicated.

Excreted into human milk: Unknown
Excreted into animal milk: Data not available

-Because of the potential for serious adverse reactions in breastfed infants, advise lactating women not to breastfeed while taking this drug and for at least 3 weeks after the last dose.

See references

References for pregnancy information

  1. Cerner Multum, Inc. "Australian Product Information." O 0
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. "Product Information. Femara (letrozole)." Novartis Pharmaceuticals, East Hanover, NJ.

References for breastfeeding information

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  2. Cerner Multum, Inc. "Australian Product Information." O 0
  3. "Product Information. Femara (letrozole)." Novartis Pharmaceuticals, East Hanover, NJ.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.