Breast cancer screening for pregnant and lactating women can be complex, with conflicting recommendations leading to confusion among patients and referring providers.1 Common concerns include potential fetal risks, effects on breast milk, imaging effectiveness due to changes in breast density, and radiation-induced cancer risks. This article clarifies the safety and efficacy of breast imaging modalities—digital mammography, tomosynthesis, contrast-enhanced mammography (CEM), ultrasound, and breast MRI—for pregnant and lactating women.
Screening protocols should align with those for non-pregnant, non-lactating women based on age, history, and risk stratification, while addressing unique considerations for fetal and infant safety.1, 2, 3 Radiologists and mammography technologists must be prepared to discuss risks, benefits, and options with patients and providers.
Understanding Radiation Safety
.png?width=216&height=151&name=BeekSpeak%20Blog%20Body%20Image%20(3).png)
No level of radiation exposure is entirely risk-free, but the risks of medical imaging are minimal and must be weighed against the benefits of early breast cancer detection 1,8.
The radiation dose from a mammogram is comparable to that from a high-altitude flight, which many women undertake without concern.1,7
The American College of Radiology (ACR) states that mammography can be performed safely at any time during pregnancy, as fetal radiation exposure is negligible1. No studies have linked low-dose medical imaging to increased cancer risk. The principle of As Low As Reasonably Achievable (ALARA) guides imaging to minimize exposure while ensuring diagnostic accuracy.
Role of the Radiologist
Radiologists play a critical role in breast imaging for pregnant and lactating patients. As imaging experts, they must:
- Tailor recommendations to the clinical scenario, considering factors like time to delivery
- Discuss risks, benefits, and alternatives with patients and referring physicians.
- Follow established protocols for imaging and standardized reporting for documentation
Patient concerns, even if perceived as minimal by the radiologist, should be addressed with empathy to develop a mutually agreeable plan.
Considerations for Pregnant Patients
Concerns about fetal harm from radiation or contrast agents often arise during pregnancy. Although scatter radiation from mammography is negligible, standard practice is to shield the abdomen to reassure patients. However, new data suggests that shielding may potentially increase internal scatter to the fetus.
As a result, the revised 2023 ACR practice parameter consensus recommendation states that ”protective shielding for the pelvis, when it is outside the field of view, is not recommended.”1
If a patient declines imaging due to perceived risks, radiologists should review the available options, discuss the benefits and risks, and develop a plan that prioritizes maternal and fetal health.
Considerations for Lactating Patients
Lactating women may worry about “contaminated” breast milk or reduced imaging accuracy due
to denser breast tissue. While lactation increases breast density, mammography can still detect cancer signs like calcifications, distortion, or adenopathy.
Delaying screening risks potentially missing a diagnosis of an early cancer. To optimize image quality and comfort, patients should pump or breastfeed prior to imaging to reduce tenderness and improve tolerance to compression.
Imaging Modalities and Safety
Below is a summary of common breast imaging modalities, their safety, and considerations for pregnant and lactating women:
Digital Mammography
- Radiation Dose: Usually <1.2 mSv per exam
- Pregnant: Safe. Fetal radiation exposure is negligible
- Lactating: Safe. No impact on breast milk; no changes to feeding required.
Tomosynthesis (3D Mammography)
- Radiation Dose: Usually <2.5 mSv per exam
- Pregnant: Safe. Use clinical judgment based on the situation
- Lactating: Safe. No impact on breast milk
Contrast-Enhanced Mammography (CEM)
- Radiation Dose: Usually 1.2-1.5 mSv per exam
- Description: Mammography with iodinated contrast
- Pregnant: Insufficient data, but, “it is likely that all iodinated contrast media crosses the blood-placental barrier and into the fetus”4; likely contraindicated.
- Lactating: Safe. Iodinated contrast is unlikely to affect breast milk significantly. If desired, patients may pump and discard milk as a precaution, though no studies quantify contrast in breast milk.5
Ultrasound
- Description: Uses sound waves, no radiation
- Pregnant: Safe at all stages; often the modality of choice
- Lactating: Safe.
Breast MRI (with Gadolinium Contrast)
- Pregnant: Contraindicated due to gadolinium crossing the blood-placental barrier4; magnetic field safe for fetus6, however, non-contrast MRI is not useful for breast cancer detection.
- Lactating: Safe. Gadolinium in breast milk is minimal, and no special precautions are needed.5
Screening with Confidence, Guided by Evidence
Breast cancer screening decisions for pregnant and lactating women should be guided by clinical need, risk stratification, and evidence-based practice.
Screening mammography (digital or tomosynthesis) is safe and indicated for women of screening age (40 for average-risk individuals; younger for high-risk individuals), with no need to defer screening during pregnancy or lactation.
Ultrasound is safe for both groups and often preferred in pregnancy.
CEM lacks sufficient data for routine use in pregnancy but is safe during lactation.
Breast MRI with gadolinium is contraindicated in pregnancy but safe for lactating women.
By following established guidelines and addressing patient concerns, radiologists can ensure timely breast cancer detection and improved outcomes without compromising fetal or infant safety.
Of course, each case will be unique, thus recommend consultation with a breast imaging specialist for tailored protocols, especially for high-risk patients, advanced maternal age or those with extended lactation.
References:
1. American College of Radiology – Society of Pediatric Radiology
ACR-SPR Practice Parameters for Imaging Pregnant and Potentially Pregnant Adolescents and Women with Ionizing Radiation
Revised 2023
2. American College of Radiology - ACR Appropriateness Criteria® - Breast Imaging During Pregnancy - Revised 2025
3. American College of Radiology - ACR Appropriateness Criteria® - Breast Imaging of Lactating Women - Revised 2018
4. ACR Manual on Contrast Media - Chapter 19: Administration of Contrast Media to Pregnant or Potentially Pregnant Patients
Revised 2025
5. ACR Manual on Contrast Media - Chapter 20: Administration of Contrast Media to Patients Who are Breast-Feeding – 2024 Evidenced Based update- Revised 2025
6. ACR Manual on MRI Safety - Chapter 15: Pregnancy - Revised 2024
7. Facts About Radiation from Air Travel - CDC.gov - February 20, 2024
8. Radiation Dose to Adults from Common Imaging Examinations - ACR Resources - Radiation Safety - Radiation Dose Reference Chart - radiologyinfo.org
