Date: May 2024, Version 4.1

Quick read

It is very important to treat a urinary tract infection (UTI) in pregnancy. Nitrofurantoin is commonly used during the first and second trimesters and is not known to affect the baby. Nitrofurantoin might also be used in later pregnancy if tests show it is the best antibiotic to treat a UTI.

What is it?

Nitrofurantoin (Macrobid®) is an antibiotic used to treat and prevent urinary tract infection (UTI).


What are the benefits of taking nitrofurantoin in pregnancy?

Nitrofurantoin can stop the unpleasant symptoms of a UTI and may also lower the chance of some pregnancy problems linked to untreated UTI, including preterm delivery.


Are there any risks of taking nitrofurantoin in pregnancy?

If a UTI is diagnosed before 28 weeks of pregnancy, nitrofurantoin is often the first-choice antibiotic and is not known to cause problems in the baby.

Nitrofurantoin tends to be avoided during the third trimester as there is a small possibility that it could lower the baby’s red blood cell levels. However, if tests show that it is the best antibiotic to treat a UTI in later pregnancy then it might still be offered, as the benefits of treatment will outweigh the possible risks.


Are there any alternatives to taking nitrofurantoin in pregnancy?

Possibly. Other antibiotics can treat UTI, but they may not work as well as nitrofurantoin. A doctor or midwife will be able to discuss why a particular antibiotic is advised as the best treatment.

No treatment

What if I prefer not to take medicines in pregnancy?

It is important that UTI in pregnancy is well-treated as it can lead to very unpleasant symptoms and also increase the risk of preterm delivery.

A doctor will only prescribe medicines when necessary and will be happy to talk about any concerns.

Will I or my baby need extra monitoring?

As part of routine antenatal care in the UK, women are invited for a very detailed scan at around 20 weeks of pregnancy to check the baby’s development. No further monitoring is required for women taking nitrofurantoin.

Are there any risks to my baby if the father has used nitrofurantoin?

There is no evidence that nitrofurantoin used by the father can harm the baby through effects on the sperm.

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

How can I help to improve drug safety information for pregnant women in the future?

Our online reporting system (MyBump Portal) allows women who are currently pregnant to create a secure record of their pregnancy, collected through a series of questionnaires. You will be asked to enter information about your health, whether or not you take any medicines, your pregnancy outcome and your child's development. You can update your details at any time during pregnancy or afterwards. This information will help us better understand how medicines affect the health of pregnant women and their babies. Please visit the MyBump Portal to register.

General information
Sadly, miscarriage and birth defects can occur in any pregnancy.

Miscarriage occurs in about 1 in every 5 pregnancies, and 1 in every 40 babies are born with a birth defect. This is called the ‘background risk’ and happens whether medication is taken or not.

Most medicines cross the placenta and reach the baby. For many medications this is not a problem. However, some medicines can affect a baby’s growth and development.

If you take regular medication and are planning to conceive, you should discuss whether your medicine is safe to continue with your doctor/health care team before becoming pregnant. If you have an unplanned pregnancy while taking a medicine, you should tell your doctor as soon as possible.

If a new medicine is suggested for you during pregnancy, please make sure that the person prescribing it knows that you are pregnant. If you have any concerns about a medicine, you can check with your doctor, midwife or pharmacist.

Our Bumps information leaflets provide information about the effects of medicines in pregnancy so that you can decide, together with your healthcare provider, what is best for you and your baby.