Epidemiological data do not suggest a clear relationship between interferon beta use and major congenital malformations, but interferon beta may cause fetal harm based on animal data.
Data from a large population-based cohort study, as well as other published studies over several decades, have not identified a drug-associated risk of major birth defects with the use of interferon beta products during early pregnancy.
Findings regarding a potential risk for low birth weight or miscarriage with the use of interferon beta products in human pregnancy have been inconsistent (see Human Data). In a study in pregnant monkeys, administration of interferon beta during pregnancy resulted in an increased rate of abortion (see Animal Data).
In the US general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown.
In a population-based cohort study conducted in Finland and Sweden, data were collected from 1996-2014 in Finland and 2005-2014 in Sweden on 2831 pregnancy outcomes from women with MS. Seven hundred ninety-seven (797) pregnancies were in women exposed to interferon beta only. No evidence was found of an increased risk of major birth defects among women with MS exposed to interferon beta products compared to women with MS that were unexposed to any nonsteroid therapy for MS (n=1647) within the study. No increased risks were observed for miscarriages and ectopic pregnancies, though there were limitations in obtaining complete data capture for these outcomes, making the interpretation of the findings more difficult.
Two small cohort studies that examined pregnancies exposed to interferon beta products (without differentiating between subtypes of interferon beta products) suggested that a decrease in mean birth weight may be associated with interferon beta exposure during pregnancy, but this finding was not confirmed in larger observational studies. Two small studies observed an increased prevalence of miscarriage, although the finding was only statistically significant in 1 study. Most studies enrolled patients later in pregnancy, which made it difficult to ascertain the true percentage of miscarriages. In 1 small cohort study, a significantly increased risk of preterm birth following interferon beta exposure during pregnancy was observed.
AVONEX has not been tested for developmental toxicity in pregnant animals. In monkeys given interferon beta by subcutaneous injection every other day during early pregnancy, no adverse effects on embryofetal development were observed. Abortifacient activity was evident following 3 to 5 doses.
For AVONEX patients considering breastfeeding, limited published literature has described the presence of interferon beta-1a products in human milk at low levels. There are no data on the effects of interferon beta-1a on milk production. Therefore, the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for AVONEX and any potential adverse effects on the breastfed infant from AVONEX or from the underlying maternal condition.
Advise patients to notify their healthcare provider if they become pregnant during treatment with AVONEX or plan to become pregnant.
Advise patients to notify their healthcare provider if they are breastfeeding or plan to breastfeed.
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