Use of penicillin antibiotics

(Date: June 2017. Version: 2.3)

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 the UK Health Security Agency (UKHSA) 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 are they?

Amoxicillin (Amix®, Amoram®, Amoxident®, Galenamox®, Rimoxallin®), co-amoxiclav (Augmentin®), and penicillin V are from a group of antibiotics called penicillins. Penicillins are used to treat a wide range of infections and are commonly prescribed during pregnancy.

Is it safe to use amoxicillin, co-amoxiclav, or penicillin V in pregnancy?

Numerous studies of use of these antibiotics in pregnancy have found no evidence of risk to the developing baby. Treatment of bacterial infections during pregnancy may be crucial to the health of both mother and baby.

When deciding whether or not to take amoxicillin, co-amoxiclav, or penicillin V during pregnancy, it is important to weigh up how necessary this 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.

What if I have already taken amoxicillin, co-amoxiclav, or penicillin V during pregnancy?

Amoxicillin, co-amoxiclav, and penicillin V are often used in pregnancy and would not be expected to harm a baby in the womb. However, if you are pregnant and have taken any medicines it is always a good idea to let your doctor know in case you need any additional monitoring or treatment.

This leaflet summarises the scientific studies relating to the effects of amoxicillin, co-amoxiclav and penicillin V on a baby in the womb.

Can taking amoxicillin, co-amoxiclav or penicillin V 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.

Large studies of women using amoxicillin or penicillin V in early pregnancy do not suggest an increased chance of birth defects in their babies. Studies investigating co-amoxiclav have produced reassuring findings, but were based on fewer women. Further research is required to confirm these results.

Can taking amoxicillin, co-amoxiclav, or penicillin V in pregnancy cause miscarriage or stillbirth?

No increased chance of miscarriage or stillbirth has been seen in large studies of pregnant women taking amoxicillin or penicillin V. Studies of co-amoxiclav have also produced reassuring findings, but are based on fewer women. Further research is required to confirm these results.

Can taking amoxicillin, co-amoxiclav, or penicillin V in pregnancy cause preterm birth or my baby to be small at birth (low birth weight)?

Studies have not shown an increased chance of preterm birth or low birth weight in babies born to mothers taking co-amoxiclav or penicillin V. A small study found an increased chance of preterm birth and low birth weight for babies exposed in the womb to amoxicillin, however, larger, more reliable studies have not agreed with these findings.

Can taking amoxicillin, co-amoxiclav or penicillin V 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.

No studies have investigated learning and behaviour of children born to mothers who took amoxicillin or penicillin V during pregnancy. Most studies that have investigated co-amoxiclav are reassuring. Antibiotics are often given to women in pre-term labour. Children born prematurely have a higher chance of learning and behavioural problems. Research that accounts for the effects of preterm birth, and also investigates the learning and behaviour of children exposed in the womb to amoxicillin and penicillin V is 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 amoxicillin, co-amoxiclav, or penicillin V during pregnancy causes any problems that require extra monitoring of your baby.

Are there any risks to my baby if the father has taken amoxicillin, co-amoxiclav, or penicillin V?

There is no increased risk to your baby if the father took amoxicillin, co-amoxiclav, or penicillin V 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 healthcare 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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