Iodine contrast prior to or during pregnancy and neonatal thyroid function: a systematic review

Objective: Thyroid dysfunction is a known side effect of iodinated contrast media. There is some evidence to suggest that iodinated contrast media administered to pregnant women may cause thyroid dysfunction not only in themselves but also in their offspring. Here, we systematically evaluated literature on the use of iodinated contrast media prior to or during pregnancy on the offspring's thyroid function. Design: Systematic review of published literature. Materials and methods: Relevant studies were identified by PubMed, EMBASE and The Cochrane Library up to June 5, 2020. All study designs, reporting on the foetal or neonatal thyroid function after exposure to iodinated contrast media prior to or during pregnancy, were included. We undertook random effects meta-analysis and pooled the estimates as proportions with 95% CIs. Results: We identified 402 articles, of which 26 were included. Six studies reported (n = 369) on exposure to iodinated contrast media prior to pregnancy by hysterosalpingography and 20 studies (n = 670) on exposure to these media during pregnancy by amniofetography, urography or CT. There was low to high risk of bias. The proportion of (transient) neonatal thyroid dysfunction was 0.0% (95% CI: 0.0-2.9% based on 3 studies) for hysterosalpingography, 2.25% (95% CI: 0.03-6.55% based on 2 studies) for amniofetography and 0.0% (95% CI: 0.0-0.02% based on 5 studies) for CT. There was a tendency towards an increased risk of thyroid dysfunction with higher amounts of contrast used. Conclusions: Exposure to iodinated contrast media prior to or during pregnancy may increase the risk of thyroid dysfunction in offspring. We recommend keeping the amount of contrast used as low as possible.