Birth outcomes in women exposed to diagnostic radiology procedures during first trimester of pregnancy: a prospective cohort study

Introduction: Exposure of the embryo or fetus to ionizing radiations is a potential danger since it may induce clinically relevant fetal and/or neonatal damages. The aim of the present study was to examine fetal and neonatal outcomes after maternal exposure to radio-diagnostic procedures during first trimester of pregnancy, and to evaluate whether these effects might be related to the fetal absorbed dose of ionizing radiations. Methods: A 10-year prospective cohort study was performed on 1979 pregnant women who underwent a radio-diagnostic procedure within the first trimester of pregnancy. Women were divided into two groups: those exposed to abdominal or lumbar radio-diagnostic procedure (Cohort A, n = 130), and those exposed to radio-diagnostic procedures in any other body regions (Cohort B, n = 415). Health physicists performed tailored fetal radiation dose calculation. Multivariate logistic regression model was used to estimate the risk of adverse pregnancy outcomes. Results: The tailored fetal radiation dose was calculated for a total of 97 women (range 0.05-92 mSv). Major congenital malformations were detected in four infants in Cohort A, six infants in Cohort B, and 24 infants in controls (p = 0.445). Multivariate analysis confirmed the negative association between age and adverse pregnancy outcomes (OR 1.08 [1.06–1.11]), and the protective role of folic acid. A higher rate of small for gestational age seems to be present in women who underwent radio-diagnostic procedures that involve maternal thyroid. Conclusion: Despite several limitations, our study confirms that exposure to radio-diagnostic procedures that may involve uterus at doses below 100 mSv does not increase the risk of embryo-fetal toxicity. The relationship between maternal thyroid irradiation and small for gestational age needs to be further investigated.