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Peginterferon alfa-2a Pregnancy and Breastfeeding Warnings

Medically reviewed by Last updated on Jul 4, 2023.

Peginterferon alfa-2a is also known as: Pegasys

Peginterferon alfa-2a Pregnancy Warnings

Animal studies with nonpegylated interferon alfa-2a have revealed a statistically significant increase in abortions, but no teratogenic effects were reported in offspring delivered at term. There are no controlled data in human pregnancy.

Pregnancy must be avoided in female patients and female partners of male patients using a ribavirin-containing regimen. Females of reproductive potential and their male partners should not receive ribavirin unless they are using at least 2 reliable forms of effective contraception during therapy and for at least 4 to 7 months after therapy. A negative pregnancy test should be obtained immediately before the start of therapy and monthly pregnancy testing is recommended during and for 6 months after ribavirin therapy.

To monitor maternal-fetal outcomes of pregnant patients or pregnant partners of male patients exposed to ribavirin, a Ribavirin Pregnancy Registry has been established. Healthcare providers and patients are encouraged to report exposures occurring during or up to 6 months before pregnancy. For additional information:

AU TGA pregnancy category B3: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.

AU TGA pregnancy category X: Drugs which have such a high risk of causing permanent damage to the fetus that they should not be used in pregnancy or when there is a possibility of pregnancy.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

US FDA pregnancy category X: Studies in animals or humans have demonstrated fetal abnormalities and/or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits.

Combination therapy: Use of a ribavirin-containing regimen is contraindicated in pregnant women and in the male partners of women who are pregnant.
Monotherapy: This drug should be used during pregnancy only if the benefit outweighs the risk to the fetus.

Combination therapy (with ribavirin):
-AU TGA pregnancy category: X
-US FDA pregnancy category: X

-AU TGA pregnancy category: B3
-US FDA pregnancy category: C

Combination therapy:
-Effective contraception (at least 2 reliable forms) is required during ribavirin therapy and for at least 4 to 7 months after the last dose; local protocol should be consulted regarding contraception timing.
-The manufacturer product information for ribavirin should be consulted.

Monotherapy: Recommended for use in women of childbearing potential only when effective contraception is used during therapy

See references

Peginterferon alfa-2a Breastfeeding Warnings

Milk levels were measured immediately postpartum (in colostrum) in 2 mothers using interferon alfa. Milk level was 1400 units/L in 1 mother using 8 million units 3 times a week and 6000 units/L in the other mother using 8 million units/day; time since previous dose not provided.

In 1 woman, peak milk level was 1551 international units/L after a dose of interferon alfa-2b 30 million units IV; was a slight increase over 2 baseline levels (averaging 1072 international units/L) before the dose. Milk interferon levels were lower than baseline by 12 hours postdose.

A woman used interferon alfa-2a 3 million units subcutaneously 3 times a week during pregnancy and postpartum for essential thrombocytopenia. Her infant was breastfed for 2 weeks postpartum before nursing was stopped due to bilateral mastitis. The infant reportedly thrived; specific measures were not provided.

A decision should be made to discontinue breastfeeding (before starting therapy) or discontinue the drug, taking into account the importance of the drug to the mother.
-AU: In addition, use in combination with ribavirin is contraindicated.

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

-The effects in the nursing infant are unknown; due to low levels in milk and poor oral absorption of interferon (similar agent) by the infant, serious harm to the breastfed infant is unlikely if this drug is used by a nursing mother.
-Level of endogenous interferon gamma (related protein) decreases about 10% with Holder pasteurization (62.5C for 30 minutes).

See references

References for pregnancy information

  1. Product Information. Pegasys (peginterferon alfa-2a). Roche Laboratories. 2002.
  2. Cerner Multum, Inc. UK Summary of Product Characteristics.
  3. Cerner Multum, Inc. Australian Product Information.

References for breastfeeding information

  1. Product Information. Pegasys (peginterferon alfa-2a). Roche Laboratories. 2002.
  2. Cerner Multum, Inc. UK Summary of Product Characteristics.
  3. Cerner Multum, Inc. Australian Product Information.
  4. United States National Library of Medicine. Toxnet. Toxicology Data Network. 2013.

Further information

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