Most drugs are not safe in pregnancy and all patients (men and women) should use contraception. If you are planning pregnancy, you should definitely discuss this with your haematologist. If you find you are pregnant, you should see your haematologist urgently and not stop taking your medication without appropriate advice.

Folic acid All women trying to become pregnant and the first third (or trimester) of pregnancy should take folic acid supplements to protect the baby from spina bifida. You can purchase folic acid supplements from any chemist.

Aspirin is safe in pregnancy. Sometimes taking aspirin may cause problems if you want a spinal anaesthetic (epidural) for pain control during labour because of a risk of bleeding. This should be discussed towards the end of pregnancy when the aspirin may be stopped.

Heparin thins the blood improving the blood supply to the placenta and the baby, and it also protects the mother against blood clots. Most patients who are already taking warfarin will be switched straight away to heparin once they are pregnant. If you are on warfarin and become pregnant you should contact your doctor urgently to arrange this switch. Heparin is given by injection either once or twice a day. Some patients may be given it only after delivery (usually 6 weeks) and others may start at different stages of pregnancy. Heparin - especially the more modern form known as low molecular weight heparin - has few side effects. Rarely it can which can cause a low platelet count and thinning of the bones or osteoporosis.

Interferon Alpha is a natural agent that reduces the production of bone marrow cells and can be used in pregnant women. Interferon alpha is given by injection three times a week. The side effects are mainly flu-like symptoms, hair loss, depression, liver and thyroid changes. Interferon alpha can pass through the mother's body to the breast milk so it is important NOT to breast feed if you are being treated with this drug.

Vitamins C and E are used by some doctors if there are problems in the pregnancy with blood supply to the placenta. These vitamins are given in tablet form.

We have been collecting information about MPD pregnancies at St Thomas' for sometime now. This includes an information document for doctors and midwives, a proposed management plan and a form to be filled in with details of the pregnancy.

This databank is a powerful tool that's increasing our knowledge about MPDs (particularly PV) and pregnancy. We're showing that active management will improve the chance of a healthy mother and baby.