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Karen Barrow

Oct. 3

• Help with Interferon Therapy: Tips from MS Nurses
• Making a Plan for MS: Why Start Treatment?

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Women with multiple sclerosis (MS) have generally been advised to stop taking their medications prior to conceiving a child and throughout pregnancy. However, for the first time, studies give a glimpse into what the risks of these drugs may be.

Both studies included women who were taking interferon beta-1a or 1b, sold as either Avonex, Rebif or Betaferon. Since this class of drug had never before been studied in pregnant women, to be cautious, patients have normally been advised to stop using the drug if they were trying to have a child or were currently pregnant.

While the two studies, published in September 2005 in Neurology, show that there may be some increased risks during pregnancy for women on MS treatment, researchers advise that they are somewhat small. If a woman does become pregnant while on therapy, it may not be necessary to seek an abortion for fear that the child will have birth defects.

The first study reviewed 69 women who had become pregnant during trials of interferon beta-1a medications. Of these women, 41 were receiving treatment at the time of conception, while 22 stopped active therapy prior to becoming pregnant. In both groups, 20 women gave birth to full-term, healthy babies.

But in those women who were on treatment at the time of conception, nine pregnancies resulted in miscarriage. (The other nine women in this group chose to have an abortion for undocumented reasons).

In the second study, led by Dr. Gideon Koren, director of the Motherisk Program at the Hospital for Sick Children at the University of Toronto, researchers looked at the success rates of 64 pregnancies, 23 of which were while patients were on interferon therapy. Ultimately, 55 percent of the women on interferons had a successful pregnancy, while 81 percent of those who had stopped the drugs gave birth to a healthy baby. The others resulted in a miscarriage.

Researchers in this study also found that average birth weight was lower in the group on interferon therapy.

Interpreting the Data
While these statistics seem to imply that women who were taking interferons were at an increased risk of having an abnormal pregnancy, looking closer at the data, the conclusion becomes less clear, write Dr. Emmanuelle Waubant and Dr. Dessa Sadovnick in an editorial that accompanied the studies.

Because both studies were small in size, the differences between the groups are hard to determine. Moreover, in the first study, some of the findings were reassuring: there was no difference in a woman's ability to become pregnant while on interferons. And while the number of miscarriages in the group taking interferons seems high, it is still within the range considered normal for healthy patients.

As for the second study, Waubant points out that although birth weights were lower, there was no difference in the number of premature births or fetal deaths in late pregnancy.

In the second study, while the researchers controlled for such risk factors as smoking and age that may lead to low birth weight, there were potentially other risk factors that were not taken into account, says Waubant.

Ultimately, because MS can affect multiple parts of the body, it is hard to determine from these studies if it is the treatment, or the disease itself, causing the complications.

"One cannot ignore the possibility that the disease itself affects reproductive outcome," explains Waubant.

Is Stopping Therapy Safe?
Pregnancy and fertility are concerns for many MS patients, as two-thirds of all patients are women, and most are diagnosed in their childbearing years. Many of these women rely on disease modifying medications to reduce the chance of relapses and to slow the progression of disease.

Even though a pregnancy may benefit from going off of therapy, forgoing the drugs for a period of time may have its own consequences for the mother-to-be. While several studies have shown that MS symptoms are reduced during pregnancy, there is a higher risk of relapse after pregnancy. Whether this incidence of relapse could be reduced by maintaining therapy during pregnancy has not yet been studied.

"Many women have a honeymoon from their MS during pregnancy," said Koren. "But each case has to be looked at independently."

Since more research is clearly needed to establish the true risks of interferon therapy during pregnancy, patients may prefer to play it safe. But they should not be overly concerned should a pregnancy occur while on the drugs, as none of the children born during these studies had any noticeable birth defects.

"Prudence suggests that discontinuation of interferon beta, and any disease modifying drug, prior to pregnancy should remain the rule whenever possible," said Waubant. "But there is no data to support aborting pregnancies conceived during interferon use."

http://abcnews.go.com/Health/Healthology/story?id=1180499&CMP=OTC-RSSFeeds0312