Pregnancy and Multiple Sclerosis: Are Drugs Safe?

Pregnancy may be protective for MS patients

/ Author:  / Reviewed by: Robert Carlson, M.D

Living with a chronic disease can be difficult. Multiple sclerosis (MS), an autoimmune disease that affects the brain and spinal cord, is a condition that’s becoming easier to treat because of advances in medicine. Still, many women worry that the disease could prevent them from having children.

MS occurs when the body’s immune system eats away at the protective sheath, called myelin, that covers nerves, which results in irreversible deterioration of the nerves. The condition is more common among women, especially women between the ages of 20 and 40 – during childbearing age.

Because of this, women with multiple sclerosis (MS) are concerned about pregnancy’s effect on their condition and the baby.

"Pregnancy reduces the frequency of attacks in MS patients."

“There’s been a lot of misunderstanding and debate about whether pregnancy is good for women with MS,” says Dr. Daniel Harrison, assistant professor of neurology at the Johns Hopkins Multiple Sclerosis Center in Baltimore.

Some patients come to his office and say they were advised not to get pregnant, but that’s false information, he says.

In fact, pregnancy has the opposite effect on MS. “It has a protective effect, hormonally,” says Harrison.

During pregnancy, women have higher levels of natural corticosteroids, an “immunosuppressant” that stops the person’s immune system from attacking their myelin. This results in a reduced frequency of MS attacks, or “relapses.”

“Women who have had multiple pregnancies have better long-term outcomes compared to women who haven’t been pregnant,” he says.

Usually, physicians won’t treat an MS patient during pregnancy, Harrison says. Especially since MS drugs can pose health risks for both mom and baby.

Certain drugs may cause short- and long-term complications for the baby, while one popular MS drug, called natalizumab, wasn’t linked to any health problems for a growing child, say studies recently presented at the annual meeting of the American Academy of Neurology in New Orleans.

Doctors currently recommend that any MS drug that reduces the frequency and severity of relapses - including natalizumab - be withdrawn three months prior to pregnancy, as doctors aren’t sure whether the drugs are excreted into breastmilk. Still, accidental exposure can happen.

In one study, researchers at the University of British Columbia in Vancouver reviewed literature published through August 2011. They found 15 studies with a total of 761 pregnant women exposed to interferon-beta, 97 to glatiramer acetate (brand name Copaxone), and 35 to natalizumab.

Study author Dr. Ellen Lu, a doctoral candidate at the University of British Columbia in Vancouver, reported their results at the New Orleans conference: Pregnant moms exposed to interferon-beta were more likely to have a baby with lower average weight at birth and lower average length at birth, as well as have a higher risk for preterm delivery. But there was no increased risk for low birth weight, congenital anomaly, cesarean delivery or spontaneous abortion.

Lu and the authors say that the other two drugs, glatiramer acetate and natalizumab, are not associated with lower mean birth rate, congenital anomaly, preterm birth or spontaneous abortion. However, they caution that there were fewer fair-quality studies conducted on both drugs.

Another study found that babies who were accidentally exposed to the drug natalizumab (brand name Tysabri) in the womb were not at increased risk for lower mean birth weight, shorter mean birth length and preterm birth. However, exposure to the drug interferon-beta increased risk for all three conditions.

In the natalizumab study, Dr. Kerstin Hellwig, from St. Josef Hospital and Ruhr University in Bochum, Germany, and colleagues looked at data from a national German registry of MS and pregnancy. They found 62 cases of exposure to natalizumab occurring at some point during pregnancy. Of these pregnancies, 48 babies were born healthy, 11 of the pregnancies ended in spontaneous abortions, one case of tubal pregnancy, and one woman who opted to terminate the pregnancy. Of the women, 22 had relapses during pregnancy.

They also found that seven babies were exposed to the drug in the third trimester. Two of the babies had profound anemia at birth. However, all of the babies in the group are now healthy.

This study shows that accidental exposure to natalizumab in the first trimester does not cause major risk to children, says Hellwig in the study. However, she adds that their study size was small and a larger study may be necessary to identify further risks.

According to the study authors, if natalizumab treatment is absolutely necessary during the second or third trimester, the baby should be closely monitored after birth.

While there are still safety concerns about MS drugs during pregnancy, it’s clear that pregnancy and pregnancy-related conditions, such as lactation, has benefits for MS patients.

In one recent study, researchers found that breastfeeding decreases the risk of postpartum relapses in the first six months after delivery. This is good news because the postpartum period can be tricky: Relapses are known to increase by 20%-40% after delivery, according to The National MS Society, when compared to the lowered rate of relapses during pregnancy.

In the breastfeeding study, researchers conducted telephone interviews with 72 women in the registry every three months during their pregnancy. The doctors were interested in whether the women breastfed or fed the baby formula. They report that 48.6% of the women breastfed exclusively for at least two months. Only 115 of these women relapsed in the first six months, compared to 32% of women who did not breastfeed exclusively or who relied on formula feedings. During the seven- to 12-month period, 34% of exclusive breastfeeders had a relapse, compared to 8% of non-exclusive breastfeeders. The team notes that the majority of exclusive breastfeeders who relapsed did so after supplemental feedings began. This means that exclusive breastfeeding acts as a treatment for a while, but it cannot be sustained, say the study authors.

Despite the risks, MS is becoming easier to manage, whether you’re pregnant or not.

There are many treatment options available to MS sufferers. One clinical trial currently underway is examining whether MS patients benefit from a drug that contains the hormone estriol, which is a hormone that rises during pregnancy and offers a protective effect to pregnant women. The study, conducted by UCLA and sponsored by the National Institutes of Health, reports that earlier results show that the drug can suppress MS symptoms.

Still, the tradeoff with newer, more aggressive drugs is that the side effects can be dangerous, says Harrison. “The drug Tysabri is the best medicine we have, but there’s a 1 in 1,000 risk of a brain infection,” called progressive multifocal leukoencephalopathy (PML), says Harrison. “It’s rare, but it can happen.”

These studies were presented at the annual meeting of the American Academy of Neurology in New Orleans. The estriol study was published in the journal Neurology Now. 

Review Date: 
May 22, 2012