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Info Centre - Radiation and pregnancy

We are all subject to natural ‘background’ radiation arising from the ground under our feet and cosmic rays coming in from outer space. Although there’s very little we can do about this, we all want to avoid unnecessary exposure, especially during pregnancy.

The use of radiation (i.e. ionising radiation − the type used in x-rays, CT scans and nuclear medicine procedures; ultrasound and magnetic resonance imaging (MRI) do not use ionising radiation at all) in medical diagnosis is responsible for the largest proportion of the avoidable radiation dose we receive.

It is the job of radiation professionals (radiologists and radiographers) to ensure that patients are only irradiated when the benefits of making a diagnosis outweigh the small risk from the radiation, and particular care is taken to avoid the exposure of women who are, or might be, pregnant.

At the low dose levels used in diagnosis, the only adverse effect is an increase in the risk of malignant disease occurring during childhood (see below). The ‘natural’ risk of childhood cancer (i.e. for a child not exposed during intra-uterine life) is about 1 in 1300.

There are two situations in which you are likely to be subjected to medical irradiation while pregnant:

  • you have an examination involving radiation and only discover later that you were in the early stages of pregnancy at the time: great care is taken to avoid this, but sometimes patients just aren’t aware of the early pregnancy at the time of their x-ray or scan, and are then naturally worried about the effects of the radiation on their unborn child. The good news is that even for the highest dose procedures likely to be carried out in hospitals, the absolute risk to the fetus is very small indeed, and at worst might increase the risk of malignancy in childhood from 1 in 1300 to about 1 in 650. For most examinations likely to be performed in this situation, the risk is considerably less than that.
  • you know you are pregnant, and a deliberate decision is taken to go ahead with an investigation using radiation: this will only happen if the doctors treating you feel that the risk to your health and that of your unborn child of not doing the scan (and thereby delaying diagnosis and treatment) is greater than the risk from the radiation. This is a much less common scenario than the previous one, and the doctors will involve you in the decision and make sure that you understand the relative risks involved.

Concern has also been expressed about the x-ray scanners (hand-held and whole body) used for security screening in some airports. The radiation dose from these is tiny – equivalent to that received every few minutes from background radiation, and it only penetrates a few millimetres into your body. However, if you are worried, you can request a body search instead.

You can find more information about the relative risks and benefits of the diagnostic use of radiation in a PDF from the Health Protection Agency here (requires PDF reader software).

Page lasted updated 2009.