What are the recommendations for counseling a patient regarding the safety of a chest X-ray during pregnancy?

A milligray (mGy) is a unit of absorbed radiation dose. A typical pregnancy is exposed to about 1 mGy of natural background radiation from the environment.

For comparison, the fetal dose from a standard two-view chest X-ray (PA and lateral) is:

• 0.0005 to 0.01 mGy

This exposure is extremely small — less than one day of background radiation — and far below thresholds associated with fetal developmental risk.

According to the International Commission on Radiological Protection (ICRP), CDC, and ACOG:

• Fetal radiation doses below 1 mGy require only verbal reassurance.
• No increase in fetal malformations, miscarriage, or growth impairment occurs at doses below 50 mGy.
• Chest X-ray, CT of the head/neck, cervical spine X-rays, extremity films, and mammography all result in less than 0.1 mGy exposure to the fetus.
• Medically indicated imaging should not be delayed because of pregnancy.

Therefore, patients can be counseled that a standard chest X-ray during pregnancy is considered safe, with negligible fetal risk. The radiation exposure is thousands of times lower than levels associated with adverse effects.