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Date of issue: August 2023, Version: 4

Formaldehyde is an organic compound that is often used in an aqueous solution called formalin. Formaldehyde is used widely in the manufacture of plastics and resins, and as a disinfectant and tissue preservative. Formaldehyde may also be produced through use of some professional keratin-based hair straightening products, potentially at levels in excess of occupational exposure limits.

Epidemiological studies assessing occupational exposure to formaldehyde during human pregnancy do not demonstrate an increased risk of miscarriage, congenital malformation, small for gestational age or preterm delivery. A single study has not provided convincing evidence of an association between in utero formaldehyde exposure and impaired infant neurodevelopment. However, data are limited and adverse effects on the fetus cannot be ruled out. Additionally, these analyses may not reflect risk where exposure in excess of recommended limits has occurred.

Unnecessary exposure to formaldehyde/formalin should be avoided due to its carcinogenic properties and general toxicity. Where occupational exposure is unavoidable, precautions should be taken to ensure that any recommended PPE is used, and that exposure is well within the recommended exposure limits and not associated with toxic symptoms.

Maternal toxicity as a result of exposure in pregnancy is likely to be a major determinant of the risk posed to the 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 fetal effects. Where maternal treatment is required, treatment should be the same as for the non-pregnant patient. 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 surveillance may be warranted after exposure to formaldehyde and should be decided on a case-by case basis. Discussion with UKTIS is recommended in all cases of formaldehyde exposure 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.