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Interferon alfa-2b Pregnancy and Breastfeeding Warnings

Brand names: Intron A

Medically reviewed by Last updated on Aug 14, 2023.

Interferon alfa-2b Pregnancy Warnings

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):
-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.

-Recommended for use in fertile women only when effective contraception is used during therapy
-Should be used with caution in fertile men

Animal studies have revealed evidence of abortifacient effects. There are no controlled data in human pregnancy.

A 26-year-old woman diagnosed with hepatitis C, at 16 weeks' gestation with twins, was successfully treated with a short-course (10 weeks) of this drug. The therapy was discontinued because of myalgia, excessive fatigue, and depressive symptoms. This patient received a total dose of 72 million units of interferon alfa. Follow-up exams of the infants, at 12 and 18 months of age, showed them doing well.

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.

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.

See references

Interferon alfa-2b Breastfeeding Warnings

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.

Excreted into human milk: Yes

-The effects in the nursing infant are unknown; due to low levels in milk and poor oral absorption 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).

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 an IV dose of this drug (30 million units); 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.

See references

References for pregnancy information

  1. Product Information. Intron A (interferon alfa-2b). Schering Corporation. 2001;PROD.
  2. Ozaslan E, Yilmaz R, Simsek H, Tatar G. Interferon therapy for acute hepatitis C during pregnancy. Ann Pharmacother. 2002;36:1715-8.
  3. Cerner Multum, Inc. UK Summary of Product Characteristics.
  4. Cerner Multum, Inc. Australian Product Information.

References for breastfeeding information

  1. Product Information. Intron A (interferon alfa-2b). Schering Corporation. 2001;PROD.
  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.