Few topics make people more careful than scans in pregnancy or for a child. The worry is understandable, and so is the wish for a straight answer. Public radiology bodies do give one, but it is a nuanced answer that depends on the scan, the body area and the reason. This page summarises what they say, quoting figures as they appear in the sources. It is general information, and the decision about any particular scan belongs to the patient or parent together with their doctor. The wider safety picture is in radiation, contrast and imaging safety.
Always tell the staff
Every source in this area opens with the same instruction. RadiologyInfo.org says it is very important to tell the doctor, the imaging technologist or the radiologist if you are pregnant before an exam that uses radiation, and to say if you are breastfeeding, preferably when you schedule. That also covers the possibility that you might be pregnant. The reason given is practical: knowing allows the team to plan your care with both you and your baby in mind.
X-ray and CT in pregnancy
RadiologyInfo.org says most X-ray exams do not pose a serious risk to the developing child, and that the actual risk depends on how far along the pregnancy is, the type of imaging and the area of the body examined. X-ray exams of the head, arms, legs and chest do not usually expose an unborn baby directly, and the technologist will typically take special precautions to make sure the baby is not directly exposed. The National Institute of Biomedical Imaging and Bioengineering (NIBIB) puts it similarly for CT: a scan poses no known risk to the baby if the area imaged is not the abdomen or pelvis.
When the abdomen or pelvis does need imaging, the sources point to alternatives first. NIBIB says doctors prefer exams that do not use radiation, such as MRI or ultrasound, but that CT may be acceptable if neither can provide the answers or there is an emergency. In RadiologyInfo.org's page on CT safety during pregnancy, the figure to know is this one: the amount of radiation in normal CT imaging has never been shown to cause harm to an unborn child, but if the scan examines the abdomen or pelvis there may be a very slight risk, and an unborn baby exposed to CT may have about a one in 1,000 greater chance of developing cancer as a child. The page adds that the level of risk is not proven and may be nonexistent, and that the radiologist and technologist will adjust the technique to lower the dose if they know you are pregnant.
It also states that you should not refuse a CT exam needed to diagnose a potentially serious or urgent illness because of fear of radiation, because the most important factor in having a healthy baby is a healthy mother. On contrast, it says that contrast material crosses the placenta, has been used in pregnancy for decades without harm, and has not been shown to harm. This is a decision for you and your doctor to make together, and nothing on this page is a recommendation to have or decline a scan.
MRI and ultrasound in pregnancy
Ultrasound is the imaging exam used most often in pregnancy. RadiologyInfo.org says it uses sound waves, not X-rays, and poses no known risk to the pregnancy. For MRI, its pregnancy page states there are no proven risks to pregnant women or unborn babies, that over the last 30 years thousands of pregnant women have had MRI exams, and that no known harmful effects to the baby have been found. The wording of cautions varies between pages, though. One RadiologyInfo.org page says the facility may reschedule a non-urgent MRI until after pregnancy, and another says pregnant people should not have an MRI in the first trimester unless the benefit clearly outweighs any potential risk. NIBIB says that while no effects on the fetus have been demonstrated, it is recommended that MRI be avoided as a precaution, especially in the first trimester.
All the sources agree on gadolinium contrast: it is normally avoided in pregnancy and used only when the information is needed to answer the doctor's question. Details about how ultrasound works and about X-ray, CT and MRI are on their own pages.
Children and radiation
NIBIB explains why children get extra attention: they are more sensitive to ionizing radiation and have a longer life expectancy than adults, which puts them at greater risk of developing cancer from such radiation. It suggests parents may want to ask the technologist or doctor whether the machine settings have been adjusted for children. RadiologyInfo.org's page on paediatric CT says high levels of radiation are known to cause cancer while CT scans result in low-level exposure, and that whether such levels cause cancer is debatable but possible, so every effort is made to limit the amount a child receives.
It lists the ways: avoiding CT scans that are not clearly needed, considering other tests such as MRI or ultrasound that might give the same information, restricting the area scanned and fine-tuning the settings to the reason for the exam, the body area and the child's size. It says children should have a CT study only if it is essential for making a diagnosis and should not have repeated CT studies unless absolutely necessary. The Image Gently campaign, an alliance for lowering dose in children's imaging, tells parents to be their child's advocate, to ask questions, and offers a printable imaging record for a child.
Keeping a child still, and parents in the room
Scans work best when the person lies still, which is hard for small children. RadiologyInfo.org says modern multidetector CT is faster than older scanners, reducing the need for sedation and general anaesthesia, and that most children over six can hold their breath long enough for a chest scan, while younger ones can breathe quietly. For MRI it says infants and young children often need sedation or anaesthesia, depending on age and the type of exam, and that a specialist in paediatric sedation should be available. Some facilities prepare children with a model scanner, recorded scanner noises or a headset to watch a film. For ultrasound it says very rarely, young children may need sedation, so parents should ask beforehand about food and drink restrictions. The page on preparing for a scan has more on what the day involves.
A parent may be allowed in the CT room wearing a lead apron, according to the same page, which adds that the radiation dose directly outside the scanner is very low and that someone who might be pregnant should let another adult accompany the child. Policies differ by facility, so ask in advance.
Frequently asked questions
Is it safe to have an X-ray while pregnant?
RadiologyInfo.org says most X-ray exams do not pose a serious risk to the developing child, and exams of the head, arms, legs and chest do not usually expose the baby directly. The actual risk depends on the stage of pregnancy, the type of imaging and the body area, so tell the staff you are or might be pregnant.
Can I have an MRI when pregnant?
RadiologyInfo.org states there are no proven risks to pregnant women or unborn babies from MRI, and that gadolinium contrast is not normally used in pregnancy. Some facilities delay non-urgent MRI, and the guidance on the first trimester is more cautious, so your radiologist will advise.
Are children more at risk from CT scans?
NIBIB says children are more sensitive to ionizing radiation and have a longer life expectancy, which puts them at greater relative risk of cancer from it. For this reason radiology bodies say children should have CT only when it is essential.
Does a child need sedation for a scan?
It depends on the scan, the child's age and whether they can lie still. Fast CT scanners reduce the need, MRI often requires sedation or anaesthesia in infants and young children, and the imaging team will explain the plan beforehand.
The short version
For pregnancy and for children, public radiology bodies emphasise telling the staff, choosing methods without radiation where they can answer the question, and using the lowest dose that gives a useful picture. They also say a needed scan should not be refused out of fear. Ask your doctor why the scan is advised and whether an alternative would do.