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Beta interferon therapy use
during pregnancy linked to miscarriage and low birth rate
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Medical Update Memo
October
24, 2005
SUMMARY
Researchers at The Hospital for Sick Children (SickKids) in
Toronto report that women being treated for multiple sclerosis
(MS) with beta interferon therapy have an increased risk
of miscarriage or low infant birth weight. The research was
reported in the September issue of the journal Neurology.
The data suggests strongly that women with MS who become
pregnant while taking beta interferon should contact their
physicians about discontinuing the drug until delivery. In
addition, women who are considering becoming pregnant and
are using beta interferon therapy should talk to their physicians
about how long they should discontinue therapy before becoming
pregnant.
DETAILS
Researchers at The Hospital for Sick Children (SickKids) in
Toronto have carried out the first prospective disease-matched
controlled study on the reproductive effects of beta interferon
therapy. Beta interferon therapies (Avonex®,
Betaseron® and Rebif®) are
the most commonly used therapies for treating relapsing-remitting
MS. Previous animal studies and human case reports have suggested
that beta interferon is not likely to increase the risk of
birth defects but there may be a risk of miscarriages. The
labelling information for the beta interferon therapies advises
women to stop taking the therapy before becoming pregnant
or to stop it immediately after becoming pregnant.
Participating in the study were 46 women,
who had contacted the Motherisk Program, a research and counselling
program at SickKids, from 1997 to 2004. A total of 64 pregnancies
were followed among these women. Group 1 was made up of 16
women (23 pregnancies) who were taking beta interferon therapy,
mostly for MS. Group 2 consisted of 12 women (21 pregnancies)
who had been taking beta interferon, mostly for MS, but had
discontinued it at least one month prior to conception. Group
3 consisted of 18 women (20 pregnancies) who did not have MS
and were not taking beta interferon.
The research team found that continued use
of beta interferon therapy through pregnancy resulted in a
39 percent increase in miscarriages, a 30 percent increase
in non-live births and a lower overall birth weight in live
births. The average birth weight of babies born to women exposed
to beta interferon was 3,189 grams (just over seven pounds).
In Group 2 (women who had stopped beta interferon therapy),
the average birth rate was 3,498 (seven pounds, 11 ounces)
and in Group 3, (healthy controls) the average birth rate was
3,783 (eight pounds, five ounces).
“ Most importantly, we recommend that
women with MS who are pregnant or planning on becoming pregnant
speak with their neurologists. Discontinuing beta interferon
therapy during gestation should not necessarily increase the
risk of relapse of MS, as pregnancy tends to reduce such risk,”
said Dr. Gideon Koren, the study's principal investigator.
Dr. Koren is a senior scientist and director of the Motherisk
Program at SickKids, as well as a professor of Paediatrics,
Pharmacology, Pharmacy and Medicine and Medical Genetics at
the University of Toronto.
In addition, women who are considering becoming pregnant and
are using beta interferon therapy should talk to their physicians
about how long they should discontinue therapy before becoming
pregnant. The researchers also recommend that women with MS
resume interferon therapy very soon after delivery if they
do not intend to breastfeed.
ASK MS Information System Code:
3.10.4.1.t
Disclaimer
The Multiple Sclerosis Society of Canada is an independent, voluntary health
agency and does not approve, endorse or recommend any specific product or therapy
but provides information to assist individuals in making their own decisions.
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