Ask the expert: pregnancy and MS

19 April 2020

MS is often diagnosed in women at a time when they're considering starting a family. Many women, and their partners, will have questions around the impact of MS on pregnancy and vice versa.

To answer some of these questions, we spoke to consultant neurologist, Ruth Dobson who is one of the experts involved in developing pregnancy care guidelines for women with MS.

Your questions answered

Does MS affect my chance of conceiving?

Ruth says: As far as we know, MS doesn't affect your chance of conceiving. It's hard to know this for sure as we don't really know how many people in the UK are trying to conceive at any one time and how many people with MS are trying to conceive. But based on the information we have got, there doesn't seem to be a significantly lower conception rate in MS or a significantly higher miscarriage rate in MS either.

If I had children, are they at higher risk of getting MS?

Ruth says: The risk of you getting MS is slightly higher if you've got relatives with the condition. If a child's mum or dad has MS, the child's risk of getting MS is around 2%. This means that around 2 in every 100 or 1 in every 50 children may go on to develop the condition.

However it's really important to note that those children are much more likely not to get MS during their lifetime than they are to ever get MS.

Are any of the DMDs safe to take whilst trying to conceive and during pregnancy?

Ruth says: First of all if you're thinking about starting a family, it's best to speak to your neurologist or MS nurse about your DMD options. Often decisions are made on a case-by-case basis depending on your personal preferences around the different DMDs and how active your MS is.

The information we have shows that Avonex, Betaferon, Extavia, Rebif, Plegridy and Copaxone are safe to take both whilst trying to conceive and during pregnancy. These medications are likely to be safe during breastfeeding as well.

For women with more active MS, the medication that's most likely to be safe, or potentially used during pregnancy, is Tysabri. There's increasing evidence around this but the risks and benefits need to be carefully weighed up for each person in discussion with their neurologist.

Another option is using medications that are used infrequently, such as Lemtrada or Mavenclad, then waiting for a while after taking the medication before trying to conceive. If you decide to do this, it is important that you talk to your neurologist about how long to wait after taking the medication before trying to conceive.

Some drugs are really not safe to be taken whilst trying to conceive and during pregnancy. It's therefore advised that women who are taking Gilenya should stop this medication at least a couple of months before trying to conceive. Similarly Aubagio should be stopped before trying to conceive. It can take a while for this medication to leave your system so this needs to be discussed early with your neurologist.

For more detailed guidance around what DMDs are safe whilst trying to conceive and during pregnancy, see the UK consensus on pregnancy in multiple sclerosis.

If you're thinking about starting a family, it's best to speak to your neurologist or MS nurse about your DMD options. Often decisions are made on a case-by-case basis depending on your personal preferences around the different DMDs and how active your MS is.


Is it safe for a man with MS to be on a DMD if they're trying for a baby with their partner?

Ruth says: This area hasn't been properly addressed by research, so unfortunately information is extremely limited. We know that small amounts of Aubagio are detected in the fluid around the sperm of men with MS. There have previously been concerns that this may be associated with a theoretical risk although there's no real evidence to back that up.

With Mavenclad, both men and women should use adequate contraception whilst taking the drug and for some time afterwards. Men should make sure they are adhering to this as well as women because we know that it does interfere with sperm quality – and there is a risk that this could be a problem for any baby that was conceived around this time.

I've heard that women with MS go into remission while pregnant and relapse after birth – is that true? If so, why?

Ruth says: On average women with MS have very few relapses during pregnancy. The chance of you having a relapse lessens the further through pregnancy you get. The reasons for this aren't particularly well understood, although we do see a similar pattern in other diseases of the immune system. We think this happens because when you're pregnant your immune system is slightly lowered as a way of trying to protect the baby from the mother's immune system. This is probably what's having the effect on the MS as well. Hormones are also likely to play a role in these changes, and they may impact on the mother's MS.

After the baby's born, research shows an increased risk of relapse in the first three months postpartum. This is thought to be due to the immune system reactivating and/or hormonal changes during this period.

What if I have a relapse when I'm pregnant? Will it harm my baby?

Ruth says: Whilst relapses are horrible things to have, and they can cause problems for the mum, they are not harmful to your baby.

Steroids can be used during pregnancy to treat relapses and help you recover quicker. We prefer to use steroids later in pregnancy rather than earlier on because during the first three months lots of important parts of the baby are being formed.

Whether you choose to use steroids or not is something that will need to be discussed with your MS team. It will involve weighing up the risks and benefits, and a consideration of the severity of the relapse and how much it's affecting you.

What is the recommended dose of vitamin D for a woman with MS who's pregnant?

Ruth says: Vitamin D may be important for the developing immune system of the baby. There are no agreed guidelines for the appropriate dose of vitamin D for women with MS who are pregnant.

The Royal College of Obstetricians and Gynaecologists has recommendations for vitamin D in all women who are pregnant, but these are not specific to MS. They recommend that all pregnant women should take at least 400 units of vitamin D a day and those that are at high risk of deficiency should take 800 units of vitamin D a day.

Trials have shown that there's no evidence of harm to the mum or the baby in pregnant women who take higher doses of vitamin D than this (up to around 4,000 units). However you should speak to your MS team about the appropriate dose for you.

Can I breastfeed?

Ruth says: Yes, women with MS can breastfeed. However, if you have highly active MS it's important to discuss the pros and cons of breastfeeding versus restarting a disease modifying drug with your neurologist.

There's some evidence that breastfeeding may be very mildly protective against relapses, but it's certainly not as good as taking a DMD. Some of the medications are safe for use in breastfeeding, in particular Avonex, Betaferon, Extavia, Rebif, Plegridy and Copaxone.

It's important to discuss your options around breastfeeding with your MS team during pregnancy so you know what your plan is in advance.

Ruth Dobson is Clinical Senior Lecturer of Preventative Neurology at Queen Mary University of London and Consultant Neurologist at Barts Health NHS Trust, London.