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Date of issue: January 2024, Version: 3

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A corresponding patient information leaflet on USE OF FLECAINIDE IN PREGNANCY is available.

Flecainide is a class Ic antiarrhythmic licensed for the treatment of AV nodal reciprocating tachycardia, arrhythmias associated with accessory conducting pathways, paroxysmal ventricular arrhythmia where the symptoms are severe and life-threatening, and paroxysmal atrial arrhythmias. It is also used occasionally as an off-license treatment for intrauterine fetal arrhythmia.

The available human pregnancy data primarily consist of two small retrospective cohort studies, a clinical trial with only a small number of flecainide exposures, case reports and small case series documenting maternal flecainide administration to treat fetal tachyarrhythmias. Two meta-analyses have been published; however, the aim was to evaluate the efficacy of transplacental treatment of fetal tachyarrhythmia, therefore limited pregnancy outcome information was reported. Furthermore, pregnancy outcomes in these reports are influenced by the underlying fetal arrhythmia for which flecainide was administered.

The number of confirmed first trimester-exposed infants identified in the literature is limited to five cases. While no malformations were reported, the number of exposures is too limited to allow accurate assessment of the risk of congenital malformation following flecainide exposure. Case series/case reports describing preterm delivery, low birth weight, intrauterine/neonatal death and neurodevelopmental delay have been published. However, these are likely to be confounded by fetal arrhythmia, for which flecainide was prescribed to treat. Given the lack of controlled prospective studies, limited conclusions regarding the fetal effects of flecainide exposure can be provided.

Maternal arrhythmia in pregnancy may impact on haemodynamic stability and placental perfusion, with potential risks to the developing fetus. Similarly, fetal arrhythmia poses a serious risk of adverse pregnancy outcome. Where flecainide is needed to treat either a maternal or fetal arrhythmia, it should not be withheld for drug safety concerns. Given the arrhythmogenic side effects of flecainide, additional fetal and maternal monitoring is required. Treatment should be overseen by a clinician with experience in treating fetal or maternal arrhythmia.

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.