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Date of issue: July 2019
Version: 2.2

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.

A corresponding patient information leaflet on macrolide antibiotic use in pregnancy is available at


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

The macrolide antibiotics include azithromycin, clarithromycin, erythromycin, spiramycin and telithromycin. Macrolides have an antibacterial spectrum similar to that of penicillin and are thus considered an alternative in penicillin-allergic patients. Indications include sinusitis, otitis media, pharyngitis, tonsillitis, bronchitis, skin and soft tissue infection. Azithromycin is also used in the treatment of chlamydia, and clarithromycin in the eradication of Helicobacter pylori.

The considerable data for macrolides as a class, and for erythromycin specifically, do not suggest an increased overall risk of congenital malformation or of cardiac malformations specifically. There are fewer data for azithromycin and clarithromycin, and although those which are available do not suggest an increased risk of congenital malformation, one cannot be excluded. There are no human pregnancy data for telithromycin. Data for spiramycin are insufficient to assess fetal risk with use during pregnancy. Use of these two macrolides should be reserved for situations where no other therapies for which human pregnancy data are available or are considered clinically appropriate. 

Three studies have suggested an increased risk of spontaneous miscarriage with clarithromycin use and one with azithromycin use in pregnancy, however data for azithromycin are inconsistent and the possibility of confounding could not be excluded. Data do not suggest an increased risk for erythromycin, or spiramycin and telithromycin but are limited for the latter two. Rates of preterm delivery, low birth weight and neonatal complications are not increased risk for macrolides as a class or individually when studied. A theoretical risk of pyloric stenosis in the neonate following macrolide exposure during pregnancy has not been supported by three large studies which found no increased rates amongst exposed offspring.

Data regarding other neonatal and longer term outcomes are absent or extremely limited. Results from two randomised controlled trials which investigated offspring neurodevelopment and cerebral palsy risk following antibiotic use in the management of spontaneous preterm labour or rupture of membranes are conflicting, although an electronic health record study has since reported a higher risk of cerebral palsy and epilepsy amongst children of women treated with macrolides during pregnancy compared to those of women receiving penicillin. Nonetheless, 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.

A single study has identified an association between asthma and in utero exposure to macrolides, but found the same for other antibiotic classes studied and did not take into account other reasons for asthma being more common in these children. 
Where possible, the results of culture and sensitivity tests should be available before making a treatment choice in accordance with local prescribing guidelines. If a macrolide is indicated, erythromycin is the preferred choice during pregnancy because there is more documented experience of its use than for other macrolides. 

Exposure to a macrolide antibiotic 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 document is regularly reviewed and updated. Only use full UKTIS monographs downloaded directly from to be sure you are using the most up-to-date version. The summaries of these monographs are openly available on

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

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