MS drug may raise risk of miscarriage
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Pregnant women being treated with beta-interferon, a drug used to fight multiple sclerosis and other diseases, face an increased risk of miscarriage or having a low birthweight baby, according to two new reports.
Dr. Gideon Koren, from The Hospital for Sick Children in Toronto, and his colleagues studied interferon’s reproductive effects in 16 women with 23 pregnancies exposed to beta-interferon, comparing them with 18 similar but unaffected women with 20 pregnancies.
In the interferon group, 55 percent of the pregnancies resulted in live births, compared with 90 percent in the healthy comparison group.
Another 12 women with 21 pregnancies had discontinued interferon treatment at least 1 month prior to conception, and the live birth rate in this group was 81 percent.
Offspring in the group exposed to interferon also weighed approximately 200 grams less at birth than those born to healthy mothers, the investigators report in the medical journal Neurology.
“Women who become pregnant while taking beta interferon should not terminate pregnancy but rather discontinue the drug until delivery,” Koren’s team advises.
In a second report, by Dr. Magnhild Sandberg-Wollheim from University Hospital in Lund, Sweden, and colleagues reviewed pregnancy outcomes of women enrolled in eight clinical trials of beta-interferon for treatment of multiple sclerosis.
A total of 69 pregnancies were reported. Forty-one occurred in women who were receiving the drug at the time of conception or had discontinued it within 2 weeks prior to conception (the “in utero” exposure group). Twenty-two occurred in patients who had discontinued treatment more than 2 weeks prior to conception (the “prior exposure” group).
In the in utero group, the spontaneous pregnancy loss rate was 29 percent, but the authors note that this rate is not significantly different from that predicted in the general population.
In the prior exposure group, there were 20 full-term healthy infants, one healthy premature infant, and one birth-related congenital defect.
The researchers conclude that “patients should still be advised to discontinue beta interferon-1a prior to planned pregnancy or if they become pregnant.”
In an accompanying editorial, two experts comment that “discontinuation of beta-interferon ... (and any disease-modifying therapy) prior to initiating pregnancy should remain the rule whenever possible.”
SOURCE: Neurology, September 27, 2005.
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