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Why was there no sign of rheumatoid arthritis when I fell pregnant?

Q) I've had rheumatoid arthritis for nearly 29 years. When I fell pregnant, there was no sign of rheumatoid in my body; so many people will tell you the same, so how come this isn't researched? Could something like the contraceptive pill take rheumatoid away?
Lynn, Carlisle, Cumbria (Summer 2010

A) You're right. This phenomenon has fascinated rheumatologists for a long time. Research has been done but I'm afraid taking the contraceptive pill isn't the answer. In fact there are many dramatic changes in a woman's body during pregnancy, most of which, unlike the bump, aren't visible. Hormonal and immunological changes occur so that the pregnancy can proceed to a successful outcome. Don't forget that the baby is a little alien as far as the mother's body is concerned, half the genetic material coming from the father. In order for the mother not to 'reject' the growing baby it must become 'tolerant'. I use inverted commas around both these words as they are terms used by immunologists. The bottom line is that for the baby to grow successfully the mother's body must undergo some immune alteration and this is probably why rheumatoid arthritis improves in pregnancy. Modern drugs to treat rheumatoid arthritis, such as methotrexate and anti-TNF drugs, also alter the immune system so in a way we're already following the body's lead on this. Of course, after delivery all these changes disappear so it's not uncommon for the rheumatoid arthritis to relapse a few weeks after delivery. This is always a letdown for the mother and is something we try and prevent by restarting treatment after the baby is delivered. Which drugs are safe in pregnancy and while breastfeeding is a whole topic on its own, which I would be happy to tackle in future answers.

This answer was provided by Dr Philip Helliwell for the Summer 2010 edition of our magazine, Arthritis Today, and was correct at the time of publication.

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