In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. This sheet talks about how multiple sclerosis may increase the risk for birth defects over that background risk. This information should not take the place of medical care and advice from your health care professional.

What is multiple sclerosis?

Multiple sclerosis (MS) is a condition that causes nerve damage that interferes with how the brain communicates with the rest of the body. Because the nerve damage can happen at any part of the brain or spinal cord, the symptoms of MS can vary. Some of the symptoms of MS are loss of balance, numbness, constipation, double vision, muscle spasms (involuntary muscle contraction), depression and fatigue. The severity of symptoms or how quickly symptoms progress also varies among individuals.

MS is likely caused by a mix of genetic and environmental factors. MS is more common in women than in men.

Will I have a harder time becoming pregnant because of MS?

In general, women with MS are as likely to become pregnant as women without MS. Some women with MS might experience sexual dysfunction, such as a decreased desire to have sex or increased vaginal dryness. These symptoms may make it harder to become pregnant.

How will pregnancy affect MS?

Women with MS will report different experiences, but many women find that their MS symptoms get better during pregnancy, especially in the third trimester. The risk of having a relapse is thought to be lower in pregnancy, especially in the third trimester, than before the pregnancy. However, doctors cannot predict for any one woman whether symptoms will get better, worse, or stay the same during pregnancy.

After pregnancy, about 15% – 30% of women will experience a relapse within 3 months of delivery. After about 12 months following the delivery, the risk of relapse goes back down to what it was before the pregnancy.

Does having MS make it more likely for me to have a miscarriage, a baby with a birth defect, or other pregnancy complications?

No. Studies have shown that women with MS are not at a higher risk than women without MS to have a negative pregnancy outcome. The rates of miscarriage, birth defects, and pregnancy complications (like giving birth before 37 weeks gestation) are similar to those expected in the general population. Studies have also shown that anesthesia, including spinal anesthesia, can be given to a woman with MS during delivery.

Rarely, a woman with significant disability may require additional help during delivery if she is too weak to push through contractions. However, most women require no additional help.

I am prescribed medication for MS. Can I take my medication during pregnancy?

There are a variety of medicines that are used to treat MS. For information on specific agents, see our medication fact sheets at https://mothertobaby.org/fact-sheets-parent/ or contact MotherToBaby toll-free at 1-866-626-6847. It is important that you discuss treatment options with your health care providers when planning pregnancy, or as soon as you learn that you are pregnant. Talk with your doctor before stopping any medication.

Can I breastfeed if I have MS?

MS does not appear to affect a woman’s ability to breastfeed. Many of the medications used to treat MS have not been well studied while nursing, but some may still be considered low risk. For information on specific agents, see our medication fact sheets at https://mothertobaby.org/fact-sheets-parent/ or contact MotherToBaby toll-free at 1-866-626-6847.

Because the risk of relapse increases after delivery, be sure to discuss options concerning breastfeeding and treating MS with your health care provider.

What if the father of the baby has MS?

Due to the symptoms of MS, it is possible that a man with MS may have fertility problems. This can be caused by sexual dysfunction or lower quality of sperm as a result of hormonal changes in MS. However, there is no evidence to suggest that a father’s MS or the medications he uses to treat MS cause birth defects. In general, a father’s exposure is unlikely to increase the risk to a pregnancy because, unlike the mother, the father does not share a blood connection with the developing baby. For more information, please see our Paternal Exposures fact sheet at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/pdf/.

MotherToBaby is currently conducting a study looking at multiple sclerosis and the medications used to treat MS in pregnancy. If you are interested in taking part in this study, please call 1-877-311-8972 or sign up at https://mothertobaby.org/join-study/.

References Available Upon Request.