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Date of issue: January 2019, Version: 2.3

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

Please note – The latest update of this monograph does not include data published after June 2017.

The penicillins; benzylpenicillin (penicillin G), phenoxymethylpenicillin (penicillin V), amoxicillin, co-amoxiclav (amoxicillin/clavulanic acid), ampicillin, flucloxacillin, temocillin, ticarcillin, piperacillin and pivmecillinam are broad-spectrum antibacterial agents indicated in the treatment of a wide range of mild to moderately severe infections caused by susceptible micro-organisms. Penicillins may be used in pregnancy if clinically indicated.

The vast majority of the large amount of available data shows no increased risk of congenital malformation, miscarriage, intrauterine death, low birth weight, preterm delivery or neonatal complications following maternal exposure to therapeutic doses of penicillins when studied either as a group or individually (although data are more limited), with the exception of flucloxacillin, piperacillin, temocillin or ticarcillin, for which there are no epidemiological studies assessing drug-specific risk. A single study has identified an association between first trimester exposure to penicillins and asthma in the offspring. Where possible associations with adverse outcomes have been identified or suggested, causality should not be assumed due to the known risks to the fetus with maternal infection during pregnancy.

Where possible, the results of culture and sensitivity tests should be available before making a treatment choice in accordance with local prescribing guidelines. It is important to ensure adequate treatment of maternal infections in pregnancy as failure to treat may lead to adverse maternal and fetal effects as a consequence of uncontrolled infection or pyrexia.

At the time of writing, the RCOG advise routine intrapartum antibiotic prophylaxis for all women in preterm labour, with or without premature ruptured membranes. Benzylpenicillin should be used preferentially, substituted for a cephalosporin in patients with a non-severe penicillin allergy, or vancomycin where the allergy is severe. NICE guidelines also state that women with pre-labour premature rupture of the membranes should be offered oral erythromycin (250 mg, 4 times a day) for a maximum of 10 days or until the woman is in established labour (whichever is sooner), with oral penicillin offered to patients who cannot tolerate erythromycin. Co-amoxiclav should not be used in patients with pre-labour premature rupture of the membranes owing to a possible increased risk of necrotising enterocolitis in the neonate.

Exposure to penicillins at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy or any additional fetal monitoring. However, 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.

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.