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Multiple sclerosis has little effect on women's chances of having a healthy pregnancy, according to the latest figures. Previously, doctors were uncertain about how the disease affected pregnancy, and some women may have been put off getting pregnant as a result.

What do we know already?

If you have multiple sclerosis, the nerves in your brain and spinal cord lose their coating over time. This affects your body in a number of ways. The most common symptoms are feeling tired, feeling weak, and getting tingling sensations. There are a number of types of MS. The most common is relapsing-remitting MS, when people feel fine for periods of time, then have periods (relapses) when their symptoms come back.

Many people are diagnosed with MS in their 20s and 30s, around the time when many women are thinking of starting a family. We already know something about how pregnancy affects the disorder. While many women with MS have fewer relapses during middle and late pregnancy, probably because of a protective effect from pregnancy hormones, they are more likely to have relapses in the 3 months after giving birth, when hormone levels return to normal.

However, there's not much research into how MS affects pregnancy. This new study, from the US, looked at what happened to 7,600 women with MS who gave birth over a 4-year period. It compared their results with pregnancies in women without any serious medical conditions.

What does the new study say?

The study is broadly reassuring. It says women with MS are no more likely to have pregnancy-related problems such as pre-eclampsia or pre-term birth than other women. However, they are more likely to have a caesarean section when they give birth, with 43 percent of women with MS having caesareans, compared with 33 percent of women without a serious medical condition. It's possible that women with MS and their doctors, are more likely to choose a planned caesarean.

Women with MS were also slightly more likely to have a baby who was small for their gestational age (the time since the pregnancy began), with 2.7 percent of babies falling into this category compared with 1.9 percent of babies born to women without a medical condition.

How reliable are the findings?

The findings come from medical records of 18.8 million deliveries in hospitals across the US. They are likely to be fairly reliable. However, the figures don't cover everything. The researchers could only look at complications that caused women to be admitted to hospital, whereas something like early miscarriage doesn't usually result in hospital admission. So the study can't tell us whether early miscarriage is more common in women with MS. The study was also unable to say whether the babies of women with MS were more likely to have birth defects, because it wasn't possible to get this information from the figures.

Where does the study come from?

The study was done by researchers from Stanford University in California, and published in the medical journal Neurology, owned by the American Academy of Neurology.

What does this mean for me?

If you're a woman with multiple sclerosis and you're thinking about having children, these findings should be reassuring. The study suggests you have a good chance of having a healthy pregnancy and birth.

What should I do now?

If you are taking drugs for multiple sclerosis, it's important to talk to your doctor before getting pregnant. Some drugs used for MS are unsafe during pregnancy. Your doctor may need to adjust your treatment.

From:

Kelly VM, Nelson LM, Chakravarty EF. Obstetric outcomes in women with multiple sclerosis and epilepsy. Neurology. Published online 19 November 2009.

To find out more about multiple sclerosis, see our information.

© BMJ Publishing Group Limited ("BMJ Group") 2009