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(Date of issue: May 2016, Version: 1.1)

This is a UKTIS monograph for use by health care professionals. For case-specific advice please contact UKTIS on 0344 892 0909. To report an exposure please download and complete a pregnancy reporting form. Please encourage all women to complete an online reporting form.


Diquat and paraquat are non-selective dipyridyl herbicides. Paraquat is no longer used in the UK. Diquat is available in commercial formulations such as Reglone® and Weedol®.

Numerous studies have raised concerns about the possible reproductive effects of pesticide and herbicide exposure as a consequence of residential proximity to agricultural fields or working in agricultural areas. However, data specifically documenting pregnancy outcome following in utero chronic low level exposure to paraquat are scarce. There are no data on pregnancy outcomes for chronic low level diquat exposure.

Adverse effects including structural malformation, pulmonary fibrosis, premature closure of the ductus arteriosus and increased resorptions have been reported in reproductive toxicity studies in some animal species. Human data are much more limited but suggest a high risk of fetal demise or toxicity following maternal ingestion. The possibility of the adverse fetal effects observed in preclinical studies should therefore be considered in such cases. No published data on the possible adverse effects of acute diquat exposure during human pregnancy have been located, but risk to the fetus is likely to be significant in cases of maternal poisoning.

One study reported a statistically significant increase in risk of childhood leukemia following pre-gestational parental exposure to paraquat. 

As with all chemicals, unnecessary exposure to these herbicides should be avoided during pregnancy. However, where occupational exposure is unavoidable then precautions should be taken to ensure that exposure is well within the recommended exposure limits and not associated with symptoms of maternal toxicity.
Management of a pregnant patient exposed to diquat or paraquat should be as for the non-pregnant patient. Maternal toxicity as a result of exposure is likely to be a major determinant of the risk posed to a developing fetus. However, due to limitations in the available data, it is not currently possible to state that an absence of maternal toxicity excludes the possibility of adverse pregnancy outcomes.

Additionally, other risk factors may be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments. Enhanced antenatal monitoring may be warranted following maternal exposure to diquat or paraquat. Discussion with UKTIS is recommended in all cases of maternal exposure.
This document is regularly reviewed and updated. Only use full UKTIS monographs downloaded directly from TOXBASE.org to be sure you are using the most up-to-date version. The summaries of these monographs are openly available on UKTIS.org.

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 health care professionals at www.toxbase.org.

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 TOXBASE.org or UKTIS.org to ensure you are using the most up-to-date version.