Thallium poisoning during pregnancy: A case report and comprehensive literature review

Background: Thallium salts were once used to treat a variety of disorders such as tuberculosis, sexually transmitted diseases, and ringworm of the scalp. Although the clinical manifestations and treatment of patients with thallium poisoning are well characterized, little information is available on the outcome of pregnancy in thallium-poisoned women. A case of thallium poisoning that began during the first trimester of pregnancy and resulted in fetal demise is reported. Methods: An extensive literature search identified reported cases of thallium poisoning during pregnancy from 1903 until the present time. All articles were obtained, translated, and abstracted using a standardized data collection form. References were hand-searched and abstracted to identify additional cases. Results: From a total of 25 cases identified, only 18 met satisfactory criteria for inclusion. Five exposures occurred during the first trimester, 5 during the second trimester, and 8 during the third trimester. Mothers developed classic signs and symptoms of thallium poisoning. Summary of these cases demonstrates a range of fetal effects from severe toxicity with residual sequelae to outwardly normal development. Interestingly, some newborns appeared normal despite severe maternal toxicity. The only consistent effect identified was a trend toward prematurity and low birth weight in children exposed during early gestation. Conclusions: These cases document the transfer of thallium both across the placenta and in breast milk. Insufficient data are available to evaluate prognostic markers of fetal outcome, or the risks and benefits of various treatment regimens in pregnant patients with thallium poisoning.