Doctors Are Cautious About X-Rays but Pregnant Women Should Stop Worrying

X-Rays Pregnant

Most people will agree that our society is very radiophobic (fearful of radiation), especially when it pertains to radiation produced by technology, such as medical devices and nuclear power. However, the amount of radiation that we receive from these technologies is far less than from natural sources, such as the Earth and the Sun. The reason for this fear dates back to more than a century ago when medical X-rays were a new technology that doctors recognized immediately for its benefits while failing to recognize the dangers if used in a haphazard way.

And the early X-ray machines were indeed used haphazardly. Because the technology was not yet developed, patients –or people getting imaged just for fun– had to keep the body part in the pathway of the X-ray beam and keep still for up to more than an hour. And yes, there were people who did it just for fun. This was depicted a couple of years ago on an episode of the Cinemax television medical historical drama, The Knick , in which the administrator of a hospital, fascinated with the new X-ray machine, takes numerous radiographs of himself, especially his hands. On the final episode, after he praises the new technology as a kind of therapy that could be used not just for specific medical purposes, but also to make people feel better, the camera focuses on the administrator’s hands, showing what appears to be some horrible cancerous growth. In real life, the inventor Thomas Edison played an important role in the development of the medical X-machine (subsequent to the discovery of X-radiation by Wilhelm Conrad Roentgen in the 1890s). Edison had an assistant whose hands were injured as a result of taking numerous X-ray scans, similar to the character on The Knick. This was around the turn of the 20th century when nobody realized that X-rays might be harmful.

During the first third of the 20th century, as scientists came to realize that X-rays and other types of ionizing radiation (radiation that strips electrons from atoms) were indeed harmful, various precautions came into effect. New applications of X-radiography were developed, which revolutionized medicine, but various safety measures were added to prevent the harmful effects. Lead shields were introduced to surround people and areas that didn’t need to be imaged, while the X-ray technology gradually improved so that less radiation was needed upstream from the shielding, and needed for increasingly shorter times, to obtain images of various parts inside the body, such as the lungs, heart, teeth, extremities, or brain. But even as recently as a half century ago, the typical medical X-ray scanners, though releasing much lower radiation doses compared with the early 1900s, they were shooting those X-rays all over the room. Consequently, radiological technicians, dentists, and others who worked with X-rays would have to wear lead gowns or stand behind a lead-shielded wall while the scanners were in use.

As the safety measures developed, so did the idea that one had to be particularly careful when it came to taking X-rays of the fetus inside the womb. They used to X-ray fetuses all the time, before ultrasonography was developed. They still do it today when needed, however, because actually X-radiation is safe for the fetus when the dosage of X-rays is kept low. That’s something that was not possible to do with the early machines.

The safety has been further improved in the case of modern X-ray imaging parts of the body remote from a pregnant woman’s womb. If you fall and hurt your wrist while pregnant for example, there is no danger in taking radiographs of your wrist to see if you have a fracture. But you wouldn’t know it, considering the papers that you’ll have to sign at the Emergency Department, or the precautions that will be taken by your dentist when she takes radiographs of your teeth. Most likely, your torso will be covered with a lead apron –some dentists will even use two aprons– as a precaution. It’s actually an unnecessary precaution and when you get a perspective on radiation exposure from the environment in which you live, you realize that such precautions actually are quite irrational.

Each day, a certain amount of ionizing radiation passes through your body and womb, depending the altitude at which you live. In places like Denver and Salt Lake City, the natural radiation exposure can be 2 -3 times that usual exposure at sea level. But babies born in Denver and Salt Lake City do not suffer a higher rate of birth defects compared with babies born at sea level. Nor is there much concern about birth defects resulting from pregnant women flying on typical commercial flights, where you can be exposed to up to a chest X-ray or two worth of radiation dosage per hour in the air, if you flight at high latitudes, as in the typical flight from New York to northern Europe. Because of this radiation, restrictions are placed on pregnant pilots and flight attendants, but no such restrictions are placed on pregnant passengers, because most passengers fly just once in a while.

Just to be clear, this radiation from flying is not dangerous for your baby, but we are mentioning it here to provide you with perspective, as it is non-focused radiation that few passengers, including pregnant passengers and their partners, ever worry about (but some do complain about the X-ray body scanners at the airport, that produce a radiation dosage far lower than a few minutes of flying). In contrast, the X-radiation that is used in modern scanners to take an image of your wrist is a focused, columnar beam. The X-ray beams use for small body parts, like teeth, are particularly narrow, almost as focused as a laser beam, and it’s not a high amount of radiation in the first place. The technology today allows the picture to be taken in a split second, and with very low power, so a radiograph would not harm your fetus, even if the beam were aimed directly at your womb. In the case of a tooth, however, the beam is not aimed at your womb. Thus, what happens is that the fetus receives no more than 1/50,000th of that already harmless X-ray dose.

Given all of this, you may be wondering why a dentist might have you wait until after the first trimester to have your routine radiographs, or why the radiologist might remind the technician to make sure to throw that lead apron over your womb. As you can imagine, the answer is not that you actually need the shielding to keep your fetus safe. The real motivation is a medical-legal issue related to the very real fact that risk of spontaneous abortion (miscarriage) happening in any given pregnancy, whether have radiographs taken or not, is substantial, particularly during the first trimester. For numerous reasons, babies can be born with birth defects. Maybe your folic acid intake is a little too low, increasing your risk of having a child with a neural tube defect. Maybe you are anxious and your stress hormones induced an abortion, or maybe –as happens frequently– the fertilization that happened in your womb was a bad apple, and so your body is eliminating it to prevent you from having a terribly ill child and giving you a chance to try again.

Whatever the reason, your doctors are aware that studies show that people, pregnant women in particular, tend to have a very distorted idea about the safety of X-rays. They know that many people, including lawyers and even some doctors, don’t appreciate how a current day X-ray scanner is not your grandfather’s X-ray scanner, and how there are dangerous doses and safe doses of radiation. They know that society is still carrying memories of horrendous X-ray injuries from those bygone days. They know that society is still confused, and so, they don’t want to get blamed should your pregnancy go awry. Consequently, they go through all the motions, putting on one lead apron, or two lead aprons, perhaps as many as three, even to the point of putting your fetus at actual risk from all the weight thrown on top of your womb.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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