Is it safe for a pregnant woman to undergo an X-ray (x-ray) examination?

X-Rays Are Safe During Pregnancy When Medically Indicated

X-rays should be performed without hesitation during pregnancy when clinically necessary, as the radiation exposure from diagnostic imaging is far below levels that could harm the fetus, and the risk of missing a serious maternal diagnosis far outweighs the negligible radiation risk. 1, 2

Radiation Safety Thresholds

The established safety margins for fetal radiation exposure are substantial and provide reassurance:

• Fetal doses below 50 mGy (50,000 mGy) show no detectable increase in adverse outcomes including malformations, growth restriction, or fetal death 3, 1
• The threshold for significant fetal harm is 100 mGy—far higher than any diagnostic X-ray delivers 3, 1, 4
• Risk of malformations only increases with doses exceeding 150 mGy 1
• All diagnostic radiological tests fall well below the 50 mGy safety threshold 3

Actual Radiation Exposure by Examination Type

Understanding the actual doses helps contextualize the minimal risk:

Minimal Risk Examinations (perform without hesitation):

• Chest X-ray: <0.01 mGy to the fetus—approximately 1/5,000,000th of the safety threshold 3, 1, 2
• Head/neck CT: <0.01 mGy—negligible fetal exposure 1, 2
• Extremity radiographs: <1 mGy—minimal exposure 1
• Mammography with abdominal shielding: safe to perform 3

Low Risk Examinations (safe when indicated):

• Chest CT: 0.3 mGy to the fetus 1
• Pelvis radiograph: 1.1 mGy 1
• Abdominal X-ray with shielding: <0.1-0.3 mGy 1, 5

Moderate Exposure (use when benefit outweighs risk):

• Single-phase abdominal CT: <20 mGy—still well below safety threshold 1
• CT abdomen/pelvis: 25-35 mGy—reserve for life-threatening situations but still below harm threshold 1

Clinical Decision-Making Framework

The medical necessity of accurate maternal diagnosis must guide imaging decisions, not theoretical fetal concerns 1, 2:

1. Question all women of childbearing age about pregnancy status before imaging 1, 5
2. For high-dose procedures like fluoroscopy, obtain pregnancy testing within 72 hours unless medical urgency prevents it 1, 5
3. Document the clinical indication and risk-benefit assessment in the medical record 1
4. Do not delay or withhold necessary imaging due to pregnancy—the risk of missing serious maternal pathology far exceeds radiation risk 1, 2

Preferred Imaging Alternatives When Appropriate

While X-rays are safe, alternative modalities may be preferred when they provide equivalent diagnostic information:

• Ultrasound is first-line for evaluating abdominal pain, pelvic pathology, and many other conditions due to lack of ionizing radiation 3, 1, 5
• MRI without gadolinium is second-line when ultrasound is inadequate or inconclusive 3, 1, 5
• MRI is generally safe in pregnancy and delivers no ionizing radiation 1
• Gadolinium-based contrast should be avoided as it crosses the placenta and has been associated with increased risk of stillbirth, neonatal death, and rheumatologic conditions 1, 2

Radiation Protection Principles

When X-rays are performed, minimize exposure using standard practices:

• Follow ALARA principles (As Low As Reasonably Achievable) 1
• Use proper abdominal shielding when feasible to minimize fetal exposure 3, 1
• Collimate the field to the area of interest 1
• Use low-dose CT protocols when CT is required 1
• Keep cumulative exposure below 50 mGy throughout pregnancy 1

Critical Pitfalls to Avoid

Do not create unnecessary anxiety that leads to diagnostic delay—most diagnostic X-rays deliver radiation equivalent to only a few days of natural background exposure 1:

• Never withhold chest X-rays due to pregnancy concerns—the fetal dose is negligible and far below any threshold for harm 3, 1
• Do not delay head/neck CT for stroke or trauma evaluation—fetal exposure is essentially zero 1, 2
• Avoid abdominal shielding for chest X-rays as it provides no meaningful benefit and may compromise image quality requiring repeat imaging 1
• Understand that fetal exposure from chest imaging comes from scattered radiation, not direct beam exposure, so external shielding is ineffective 1
• Radioactive iodine is contraindicated as it crosses the placenta and affects the fetal thyroid after 12 weeks gestation 1

Special Clinical Scenarios

Suspected Pulmonary Embolism:

• Perform chest X-ray first, then proceed to CT pulmonary angiography if needed—total fetal dose remains <0.3 mGy 1
• Perfusion lung scintigraphy is also reasonable with high diagnostic yield (75%) in pregnant women 3
• D-dimer should still be measured despite physiologic elevation in pregnancy, as 50% of women have normal levels at 20 weeks 3

Suspected Appendicitis:

• Ultrasound first-line, MRI second-line 1, 5
• Obtain β-hCG before imaging in premenopausal women to prevent inadvertent exposure and narrow differential diagnosis 5

Contrast Agent Use:

• Iodinated IV contrast appears safer than gadolinium 1, 2
• Modern non-ionic iodinated contrast has minimal risk of neonatal hypothyroidism 1, 2
• Less than 0.01% appears in breast milk—breastfeeding is safe after administration 1
• Use contrast only if absolutely required to obtain diagnostic information that would affect care 1

Risk Communication with Patients

Reassure pregnant patients that diagnostic X-rays pose no measurable risk to the fetus 1, 2, 6:

• Explain that fetal doses from most X-rays are 1,000-10,000 times lower than the threshold for any harm 1, 2
• Emphasize that no adverse effects are expected at diagnostic exposure levels 2, 4, 7
• Clarify that radiation exposure is not an indication for pregnancy termination at diagnostic doses 6, 4
• Stress that the benefit of accurate maternal diagnosis far outweighs negligible fetal risk 1, 2