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Date of issue: November 2018, Version: 2

Metallic arsenic is used in the production of semi-conductors and in industrial processes for strengthening metals. Arsenic and its compounds may occur naturally in groundwater and are used in the production of pesticides, herbicides and insecticides, although this practice is decreasing. Arsenic trioxide is used to treat adult patients with relapsed/refractory acute promyelocytic leukaemia where previous treatment with retinoids has failed.

There are no data to assess the safety of the therapeutic use of arsenic trioxide in pregnancy, therefore its use cannot be recommended. However, if clinically indicated, maternal treatment should not be withheld on the basis of pregnancy.

The results of studies investigating the fetal effects of environmental exposure to arsenic through drinking water or air pollution during pregnancy are likely to be heavily confounded by unmeasured concomitant exposures and other lifestyle/sociodemographic factors. As such, it is difficult to attribute causality of any detrimental effects observed to prenatal environmental arsenic exposure alone. The results from these studies are also occasionally conflicting. Some studies have associated environmental exposure to arsenic through drinking water or air pollution during pregnancy with overall congenital malformation, cardiovascular malformation, spontaneous abortion, stillbirth, small for gestational age or preterm birth risks, and neonatal/childhood complications including infections, neurodevelopmental impairments and morbidity. Associations with decreased infant birth weight have also been demonstrated. Although dose-response relationships have been defined in some studies, a threshold dose above which risk of adverse fetal effects is increased remains to be defined. 

Acute maternal arsenic poisoning during pregnancy may result in maternal and/or fetal death. Owing to the potential severity of arsenic exposure, treatment during pregnancy should be the same as for the non-pregnant patient. Maternal toxicity is likely to be a major determinant of risk to the fetus following arsenic exposure.

Enhanced antenatal surveillance may be warranted and should be decided on a case-by-case basis. Discussion with UKTIS is recommended in all cases where exposure to arsenic has occurred at any stage of pregnancy.

This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to NHS health care professionals who are logged in.

If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.

If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.

Disclaimer: Every effort has been made to ensure that this monograph was accurate and up-to-date at the time of writing, however it cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes of the measures recommended. The final decision regarding which treatment is used for an individual patient remains the clinical responsibility of the prescriber. This material may be freely reproduced for education and not for profit purposes within the UK National Health Service, however no linking to this website or reproduction by or for commercial organisations is permitted without the express written permission of this service. This document is regularly reviewed and updated. Only use UKTIS monographs downloaded directly from to ensure you are using the most up-to-date version.