New study suggests link between birth defects and preconception CT imaging
New research is spurring new questions about how preconception radiation exposure impacts fetal development during pregnancy.
The study, which was published in Annals of Internal Medicine earlier in September, includes data from more than 5 million pregnancies and 3.4 million live births that took place between 1992 and 2023. After reviewing the data, experts noted associations with preconception radiation exposure during CT imaging and birth defects.
While they acknowledged that their work does not necessarily prove causation, they suggested that their findings raise concerns regarding women who are planning on becoming pregnant and imaging-related radiation exposure in the weeks leading up to conception. The findings are especially relevant considering the growing utilization of CT exams.
“The use of computed tomography scans in medicine continues to increase, and adverse events related to CT scan–associated radiation are not well understood. Recent studies have focused on oncogenic effects. Because this research is based on modeling using data from Japanese atomic bomb survivors and radiation workers, it can be controversial,” Seth M. Hardy, MD, MBA, Penn State Health, wrote in an editorial accompanying the study. “These models depend on transparency from the U.S. Department of Defense regarding the effects of their weapons on survivors, as well as data from military personnel exposed to radiation during testing.”
For the study, the team compared instances of pregnancy complications and birth anomalies to confirmed CT scans that the women underwent up to four weeks prior to conceiving. Pregnancy complications included spontaneous pregnancy loss (miscarriage, ectopic pregnancy or stillbirth) among recognized pregnancies and congenital anomalies diagnosed within the first year of life among live births.
Those who underwent CT imaging in the month prior to conception faced progressively higher risks, which increased alongside the number of scans. Compared to those with no radiation exposure, women who underwent one, two, and three or more CT scans were associated with adjusted hazard ratios of 1.08, 1.14 and 1.19, respectively, for spontaneous pregnancy loss; these figures were 1.06, 1.11 and 1.15 for congenital anomalies in live births. Rates of spontaneous loss ranged from 101 to 142 per 1,000 pregnancies across exposure groups, while anomaly rates increased from 62 to 105 per 1,000 births in the CT group.
Of note, the team did not observe decreased risks based on the type of CT scan completed. For example, head CTs did not show consistently lower risk than imaging of the abdomen, pelvis or spine.
The group acknowledged that their work had limitations, but maintained that their findings provide enough evidence to support cautious consideration in women during the time when they are trying to conceive.
“Exposure to preconception CT imaging may be associated with higher risks for spontaneous pregnancy loss and congenital anomalies, but causal mechanisms remain to be elucidated,” the authors concluded. “Alternative imaging methods should be considered when appropriate.”
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In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.