(Date: June 2017. Version: 2.1)

This factsheet has been written for members of the public by the UK Teratology Information Service (UKTIS). UKTIS is a not-for-profit organisation funded by Public Health England on behalf of UK Health Departments. UKTIS has been providing scientific information to health care providers since 1983 on the effects that medicines, recreational drugs and chemicals may have on the developing baby during pregnancy.

What is it?

Erythromycin is a type of antibiotic called a macrolide and is used to treat a wide range of infections.

Is it safe to use erythromycin in pregnancy?

Erythromycin is commonly prescribed during pregnancy, with no known harmful effects for the developing baby.

The timely and correct treatment of potentially severe bacterial infections during pregnancy may be crucial to the health of both mother and baby. When deciding whether or not to take erythromycin during pregnancy it is important to weigh up how necessary it is to your health against the possible risks to you or your baby, some of which will depend on how many weeks pregnant you are. Your doctor is the best person to help you decide what is right for you and your baby.

You should not alter the dose of any of your medicines without medical supervision. Your doctor is the best person to help you decide what is right for you and your baby.

What if I have already taken erythromycin during pregnancy?

Erythromycin is commonly used in pregnancy and would not be expected to harm a baby in the womb. However, it is always a good idea to let your doctor know that you are pregnant if you have taken or are taking medicines in case you need any additional monitoring or treatment.

This leaflet summarises the scientific studies relating to the effects of erythromycin on a baby in the womb. 

Can taking erythromycin in pregnancy cause my baby to be born with birth defects?

A baby’s body and most internal organs are formed during the first 12 weeks of pregnancy. It is mainly during this time that some medicines are known to cause birth defects.

Six studies, which together included babies of over 5,900 pregnant women who took erythromycin in early pregnancy, all found no link between birth defects in the baby and use of erythromycin. Although a further three studies did identify possible links between birth defects in the baby and exposure in the womb to erythromycin, problems with the methods used to collect and analyse the data in these studies mean that the results may not be reliable.

Three of the four large studies that investigated a possible link between exposure to erythromycin in the womb and heart defects in the baby found no evidence of a link. Although this is reassuring, because the fourth study did identify a possible link, further research into this subject is ideally required.

Can taking erythromycin in pregnancy cause miscarriage?

A single study found no link between erythromycin use in early pregnancy and miscarriage. More research is therefore required to confirm this finding.

Can taking erythromycin in pregnancy cause stillbirth?

A single study found no link between erythromycin use in pregnancy and stillbirth, or death of the baby within the month after birth. More research is therefore required to confirm this finding.

Can taking erythromycin in pregnancy cause preterm birth or my baby to be small at birth (low birth weight)?

A single study found no link between erythromycin use in pregnancy and preterm birth or low infant birth weight. More research is therefore required to confirm this finding.

Can taking erythromycin in pregnancy cause learning or behavioural problems in the child?

A baby’s brain continues to develop right up until the end of pregnancy. It is therefore possible that taking certain medicines at any stage of pregnancy could have a lasting effect on a child’s learning or behaviour.

Studies that have investigated whether children who were exposed in the womb to erythromycin are at increased risk of learning and behavioural problems compared to children not exposed to antibiotics have produced mixed findings. However, most of these studies were of antibiotic use in women who had gone into premature labour. Preterm birth has itself been linked to an increased risk of learning and behavioural problems in children. It is therefore possible that prematurity of the baby, or the reason for premature labour, account for some of these findings, rather than erythromycin use by the mother during pregnancy. Further research into this subject is therefore required.

Will my baby need extra monitoring during pregnancy?

As part of their routine antenatal care most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects and to check the baby’s growth.

There is no evidence that taking erythromycin during pregnancy causes any problems that would require extra monitoring of your baby. 

Are there any risks to my baby if the father has taken erythromycin?

We would not expect any increased risk to your baby if the father took erythromycin before or around the time you became pregnant.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet please discuss them with your health care provider. They can access more detailed medical and scientific information from

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General information 

Up to 1 out of every 5 pregnancies ends in a miscarriage, and 1 in 40 babies are born with a birth defect. These are referred to as the background population risks.  They describe the chance of these events happening for any pregnancy before taking factors such as the mother’s health during pregnancy, her lifestyle, medicines she takes and the genetic make up of her and the baby’s father into account.

Medicines use in pregnancy

Most medicines used by the mother will cross the placenta and reach the baby. Sometimes this may have beneficial effects for the baby.  There are, however, some medicines that can harm a baby’s normal development.  How a medicine affects a baby may depend on the stage of pregnancy when the medicine is taken. If you are on regular medication you should discuss these effects with your doctor/health care team before becoming pregnant.

If a new medicine is suggested for you during pregnancy, please ensure the doctor or health care professional treating you is aware of your pregnancy.

When deciding whether or not to use a medicine in pregnancy you need to weigh up how the medicine might improve your and/or your unborn baby’s health against any possible problems that the drug may cause. Our bumps leaflets are written to provide you with a summary of what is known about use of a specific medicine in pregnancy so that you can decide together with your health care provider what is best for you and your baby.   

Every pregnancy is unique. The decision to start, stop, continue or change a prescribed medicine before or during pregnancy should be made in consultation with your health care provider. It is very helpful if you can record all your medication taken in pregnancy in your hand held maternity records.

Disclaimer: This information is not intended to replace the individual care and advice of your health care provider. New information is continually becoming available. Whilst every effort will be made to ensure that this information is accurate and up to date at the time of publication, we cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes following decisions made on the basis of this information. We strongly advise that printouts should NOT be kept for any length of time, or for “future reference” as they can rapidly become out of date.

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