Pregnancy and multiple sclerosis

Multiple sclerosis (MS) is a long-term condition in which the majority of people suffer relapses, which are due to abnormal inflammation in a part of the brain or spinal cord. Typical relapses can be blurred vision in one eye, unsteadiness, weakness in both legs or weakness down one side of the body. It is a type of autoimmune condition in which the immune system is causing the abnormal inflammation and treatment is usually by weakening the immune system. MS typically affects young women, so pregnancy is a common clinical scenario. There are two main aspects to consider. Firstly, what is the impact of pregnancy and breastfeeding on MS? Secondly, what about MS treatments being used in pregnancy or during breastfeeding?

Impact of pregnancy and breastfeeding on MS

Women are about 1/3 as likely to have a relapse during pregnancy compared to before or after (in other words about a 70% risk reduction). This is a huge reduction and is slightly better than some of the most effective MS treatments available, such as natalizumab (also called Tysabri, which reduces risk by about 68%). Why is this?

It seems to be partly because pregnancy is a state of natural immunosuppression. We have adapted to prevent rejection of a fetus (which has a different genetic make-up to the mother’s body) by dampening down the immune response. This means that many autoimmune diseases tend to improve during pregnancy.

In addition, increased estrogen and progesterone levels may help healing of damaged brain and spinal cord cells.

After delivery, the risk of a relapse increases above normal for the first 3-6 months to almost twice the normal risk. This rebound effect occurs as the benefit of pregnancy wears off and the MS disease seems to ‘catch up’ with the delay from pregnancy. Breastfeeding can reduce this risk markedly though.

In the longer term, some studies even suggest that pregnancy may reduce or delay progression of MS overall.

MS treatments during pregnancy and breastfeeding

Before becoming pregnant, women should talk to their neurologist and also take vitamin D supplements. The following information is not clinical advice.

UK guidelines suggest that some treatments may have no or little increased risk in pregnancy. With other drugs, there is a minimum time period during which women should not become pregnant. Some of the guideline recommendations are:

  • Copaxone injections may be continued in pregnancy. Other interferon-beta injections may have no increased risk in pregnancy.
  • Natalizumab infusions in early pregnancy may be used if the benefit outweighs the risk.
  • Alemtuzumab use means pregnancy should be avoided for at least 4 months
  • Cladribine use means pregnancy should be avoided for at least 6 months
  • Ocrelizumab use means pregnancy should be avoided for at least 12 months
  • Most drugs should be avoided during breastfeeding
  • Corticosteroids may be safe to give if a relapse occurs during pregnancy or breastfeeding

Further information for doctors is available here (Dobson et al, 2018. UK consensus on pregnancy in multiple sclerosis. Pract Neurol)

Further information on pregnancy for people with MS is available here

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