Pre-conception computed tomography ionizing radiation may be associated with worse reproductive outcomes

1. In this population-based cohort study, women who had received at least one computer tomography scan prior to conception had higher rates of spontaneous pregnancy loss and congenital anomalies compared with women without a prior scan.

2. Rates of both spontaneous pregnancy loss and congenital anomalies increased with the number of scans performed.

Evidence Rating Level: 2 (Good)

Study Rundown: Ovarian follicles in non-pregnant women may be exposed to high-dose ionizing radiation from imaging modalities including computed tomography (CT) scans, potentially causing genetic mutations or chromosomal changes. However, the impact of CT radiation exposure long before pregnancy on pregnancy viability or the risk of congenital anomalies remains unknown. This study aimed to determine whether female exposure to CT ionizing radiation in the years prior to conception affected the risk of spontaneous pregnancy loss or congenital or chromosomal anomalies. It was found that women who had received one CT scan had higher rates of spontaneous pregnancy loss compared to women without a prior scan; rates of spontaneous pregnancy loss increased with more scans performed. Absolute rates of pregnancy loss were slightly higher among women who underwent imaging of the abdomen, pelvis, or lower spine. Rates of spontaneous pregnancy loss also increased as time between the most recent CT scan and conception decreased, leading to a peak at four to eight weeks pre-conception. Women with one prior CT scan had higher rates of congenital anomalies compared with women without a prior scan, and rates of spontaneous pregnancy loss also increased with more scans performed, regardless of how long prior to conception the scans were done. The generalizability of this study is limited by missing data on women who had a miscarriage but did not visit health care for their pregnancy, as well as on congenital anomalies among women with induced abortions. Nevertheless, this study suggests that CT ionizing radiation may negatively affect pregnancy viability and risk of congenital anomalies among women of reproductive age.

Click to read this study in AIM

Relevant Reading: Use of Pelvic Computed Tomography and Sonography in Women of Reproductive Age in the Emergency Department

In-Depth [retrospective cohort]: This population-based cohort study aimed to evaluate the impact of CT scan ionizing radiation on rates of spontaneous pregnancy loss and congenital abnormalities among women of pregnancy age. Data were obtained from health administrative databases in Ontario among women aged 16 to 45 years. Women were excluded if they had potentially prothrombotic risk factors or had CT imaging done during pregnancy. The primary outcome was spontaneous pregnancy loss, in particular a miscarriage or ectopic pregnancy before 20 weeks’ gestation or a stillbirth at or after 20 weeks’ gestation, while the secondary outcome was any congenital or chromosomal anomaly among live births, diagnosed between 0 and 365 days after the birth. A total of 5,142,339 women with recognized pregnancies were included in this study, 687,692 (13.4%) of whom had a CT scan, with a median duration of 50 months (interquartile range [IQR], 21 to 96 months) between the most recent CT scan and conception. Women who had a CT scan were more likely to have diabetes mellitus (2.2% vs. 1.4%) or chronic hypertension (3.7% vs. 1.6%). Spontaneous pregnancy loss occurred in 535,165 (10.4%) pregnancies. Rates of spontaneous pregnancy loss were 101 per 1000 recognized pregnancies among women without prior CT scans, 117 per 1000 with 1 CT scan, 130 per 1000 with 2 scans, and 142 per 1000 with 3 or more scans. The adjusted hazard ratios (aHRs) relative to women without prior scans were 1.08 (95% CI, 1.07 to 1.08) among women with 1 scan, 1.14 (95% CI, 1.12 to 1.16) with 2 scans, and 1.19 (95% CI, 1.16 to 1.21) with 3 or more scans. Women with CT also saw increased rates of spontaneous pregnancy loss and aHRs as duration between the most recent CT and conception decreased, with a peak at 4-8 weeks before conception (128 per 1000; aHR, 1.24 [95% CI, 1.18 to 1.30]). Among 3,451,968 identified live births, 225,002 infant congenital anomalies were identified at birth or during the first year of life. Rates of congenital anomaly were 62 per 1000 live birth pregnancies among women without prior CT scans, 84 per 1000 with 1 CT scan, 96 per 1000 with 2 scans, and 105 per 1000 with 3 or more scans; this corresponded to aHRs of 1.06 (95% CI, 1.05 to 1.08) among women with 1 scan, 1.11 (95% CI, 1.09 to 1.14) with 2 scans, and 1.15 (95% CI, 1.11 to 1.18) with 3 or more scans. Overall, this study suggests that exposure to CT scan ionizing radiation prior to conception may lead to increased risk of spontaneous pregnancy loss and congenital anomaly.

Image: PD

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