What is radiation?

Radiation is energy that travels through air and some materials as waves or tiny particles. We are exposed to radiation from different natural and artificial sources every day. These include the sun, microwaves and radio waves.

In Australia, people get about 1.5 to 2 millisieverts (mSv) of ionising radiation every year from natural sources. This level of radiation is not harmful.

Which medical procedures give off radiation?

The type of radiation used in medical imaging is called ionising radiation.

If you are pregnant or think you might be pregnant, you should be cautious about medical procedures that use radiation, like:

• x-rays
• CT scans
• mammography
• fluoroscopy
• nuclear medicine
• angiography

An x-ray exposes you to up to 8mSv and a CT scan exposes you to up to 10mSV of ionising radiation. The exposure depends on the body part and type of imaging required.

X-rays and some other types of radiation can change the molecules that make up the body. At high enough doses, radiation can kill cells and damage DNA.

If you’re pregnant or thinking about becoming pregnant, tell your doctor and the radiology practice before you have any tests. You can discuss whether they can be delayed or avoided, and whether there are alternative tests.

Tests that don’t use radiation, such as magnetic resonance imaging (MRI) or ultrasound, may be useful alternatives in some situations.

What are the effects of radiation on me and my unborn baby?

Most radiation exposure during medical testing is unlikely to harm your developing baby.

But sometimes, depending on the radiation dose and the stage of your pregnancy, the effects can be serious and may result in:

• miscarriage
• congenital disorders
• changes to your baby’s central nervous system
• changes in your baby’s physical development
• slower than normal growth
• cataracts
• childhood or lifetime cancer

Any harm to your developing baby will depend on:

• the radiation dose — smaller doses (amounts) are safer
• the stage of your pregnancy — the further along you are in your pregnancy, the better
• where in your body the radiation is given — tests involving your abdomen (tummy) or pelvis, or where the radiation is carried in your blood, have a higher risk than other tests

Here is a summary of some of the potential health effects that radiation could have on your baby during pregnancy:

	100–500mSv	More than 500mSv
Up 2 weeks pregnancy	Your embryo might not implant in your uterus.	Your embryo is not likely to implant in your uterus. If it does, your baby will probably have health issues.
3rd to 5th weeks of pregnancy	Your baby may not grow as much as expected.	Your baby may not grow as much as expected. Your chance of a miscarriage may be higher. The baby might have major differences.
6th to 13th week of pregnancy	Your baby may not grow as much as expected.	Your baby may not grow as much as expected. Your chance of a miscarriage may be higher.
14th to 23rd weeks of pregnancy	Health effects are unlikely	Your baby may not grow as much as expected. Your chance of a miscarriage may be higher. Your baby might have major differences.
24th week of pregnancy to term	Health effects are unlikely.	Miscarriage and baby death may occur.
For radiation exposures of 100mSv or less at any time during pregnancy, there are no health effects.

Radiation exposure while pregnant may increase your child’s risk of cancer later in life, for radiation doses above 100mSV (this is well above typical doses received in diagnostic radiology). However, this risk is very small — estimated to increases by about 0.1%. Talk to your doctor for more information about your individual circumstance.

What if I am exposed to radiation from medical imaging?

If you are accidently exposed to radiation from medical imaging while you’re pregnant, you should talk to your doctor.

The risk to your baby can be worked out using a formula and can be calculated by an expert. A single exposure to radiation is not likely to be harmful to your baby.

What about radiation in my workplace?

If you are pregnant or planning to become pregnant, and your work exposes you to radiation, it is important to discuss alternative roles with your employer.

What if I am exposed to radiation in an emergency?

If you are exposed to radiation in an emergency, you should follow instructions from emergency officials and seek medical attention as soon as possible.

Usually, your baby will receive less radiation than you. Your abdomen (tummy) partially protects your baby.

However, if you swallow or breathe in radiation, it can reach your baby. Your baby is most sensitive to radiation from 2 to 18 weeks of pregnancy.

Can I breastfeed after being exposed to radiation?

Radioactive material can be passed to babies through breast milk.

Breastfeeding mothers undergoing radiotherapy should ask a health professional for advice.

If you are exposed to radiation while you are breastfeeding, you should feed your baby with pre-pumped and stored breast milk or formula.

Speak to your doctor or health professional about when to start safely breastfeeding again.

What about radiotherapy for cancer?

Radiotherapy, or radiation therapy, is a treatment for some cancers.

You may be advised to have radiotherapy as a treatment for cancer during your pregnancy. If you’re in this situation, you and your doctor can weigh up the benefits of the radiotherapy against any potential harm to your developing baby.

If you suspect you may be pregnant at any stage of radiotherapy, you should discuss with your doctor whether to continue the treatment.

Resources and support

Speak to your doctor and the medical imaging technologist if you are pregnant and need a scan or test that might involve radiation.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.