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X-ray Radiation and Pregnancy

Overview

X-rays are a type of high energy radiation that, depending on the dose, can reduce cell division, damage genetic material, and produce defects in unborn children. Cells that divide quickly are most sensitive to x-ray exposure. Unborn children are particularly sensitive to x-rays because their cells are rapidly dividing and developing into different types of tissue. Exposure of pregnant women to sufficient doses of x-rays could possibly result in miscarriage or damage to unborn children, including malformations or development of cancer later in life. With most x-ray procedures, relatively low levels of radiation are produced. However, as a safety precaution, the use of x-rays in pregnant women should be avoided unless absolutely necessary. Women who receive x-rays before realizing they are pregnant should speak to their doctors. Some pregnant women may be exposed to x-rays in the workplace; therefore, the federal government has established limits to protect unborn children from radiation exposure in work settings.

Description of X-rays

X-rays are a type of high energy ionizing radiation that upon contact with materials cause them to lose electrons and become charged (ionized) (NRC Glossary, 1999). Exposure to x-rays is measured in units of radiation absorbed dose (rad), the amount of radiation absorbed per unit mass of material. Rads are often converted to units of rem by multiplication with quality factors to account for biological damage produced by different forms of radiation. The quality factor for x-rays is 1, so rads and rems are equivalent (NRC 10 CFR 20.1004).

Depending on the dose, exposure to x-rays can result in diminished cell division, damage to genetic material, and damage to unborn children (NRC, 1999, Biological Effects of Radiation). Rapidly developing cells are the most sensitive to x-ray exposure (NRC, 1999, Biological Effects of Radiation). It is important to note that x-rays affect only those body tissues which come into direct contact with the beam (March of Dimes, September 1997). For example, the x-ray of a hand would not result in radiation traveling to the reproductive organs.

X-rays and Pregnancy

Unborn children are particularly sensitive to x-rays because their cells are quickly dividing and developing into different types of tissues (ICN Pharmaceuticals, 1997). Depending on the level of exposure, x-rays conducted on pregnant women could potentially lead to miscarriage or defects in unborn children including malformations, reduced growth, or development of cancer later in life. According to the Nuclear Regulatory Commission (NRC), children exposed to 2–6 rads of x-rays in utero have an increased chance of developing cancer (NRC, 1999, Biological Effects of Radiation). However, the March of Dimes has reported that studies found no significant relationship between exposure of pregnant women to 5–10 rads of x–rays and malformations in their children (March of Dimes, September 1997).

The effects of x-rays on unborn children depend upon the period of pregnancy during which the x-ray was conducted. The following table summarizes possible effects of x-ray exposure according to the time of pregnancy at which exposure occurred (NRC, 1999, Biological Effects of Radiation, March of Dimes, September 1997):

The British Columbia Ministry of Health has estimated exposures received by unborn children after mothers were x-rayed before realizing they were pregnant (British Columbia Ministry of Health, 1999). They found that unborn children are typically exposed to 0.5–1.5 rads following most types of abdominal or lower back x-rays of the mother, and x-rays in distant body parts generally result in exposures that are 10–100 times lower. Again, the NRC considers 2 rads to be the lowest exposure level for possible damage to unborn children (NRC, 1999, Biological Effects of Radiation).

Women who have been x-rayed before realizing they are pregnant should talk to their doctors. All women who are or may be pregnant should inform their doctors, and x-rays should not be conducted unless they are absolutely necessary (Columbia University, 1999). Informing doctors about pregnancy allows them to either postpone the x-rays or to take all necessary precautions to reduce exposure to the unborn child.

Occupational X-ray Exposure

Federal laws have been established to protect the unborn children of women exposed to radiation in the workplace. In the workplace, the dose of radiation to an unborn child throughout the entire pregnancy cannot exceed 0.5 rem. For x-rays, rem and rad are equivalent and the limit of exposure for unborn children is therefore 0.5 rads (NRC 10 CFR 20.1208).

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