Guidance

Use of medicines in pregnancy and breastfeeding

Information for patients, healthcare professionals and developers of new medicines

From:
Medicines and Healthcare products Regulatory Agency
Published
11 January 2021
Last updated
10 August 2022 — See all updates

1. Medicines in pregnancy

Women may sometimes need to take medicines to protect their own health and the health of their baby during pregnancy.

Advice for patients

  • If you are pregnant or planning a pregnancy and you need to take a medicine, speak to your doctor, pharmacist, or midwife because some medicines may affect the baby’s development. They can advise on the risks and benefits for you and the baby to help you decide what to do.
  • If you have a chronic or recurring condition that requires long-term treatment, it is especially important to ask your doctor whether any changes are needed to your medicines.
  • Do not stop taking prescribed medicines without talking to your doctor. The benefits of continuing your medication may be greater than any risks.

Further information is available from the following websites:

For patients and their families

For healthcare professionals

Medicines to avoid during pregnancy

Some medicines are known to be harmful in pregnancy. They may affect the development of the baby or mean the baby is more likely to be born with a disability.

Medicines may especially affect the baby during early development. This occurs in the first trimester which is 13 weeks since a woman’s last period. During this time a woman may not know she is pregnant.

When using any medicine that is known to be harmful in pregnancy:

  • a woman should be advised of the risks to the baby if she were to become pregnant. She should be encouraged to use effective contraception throughout treatment. Contraception can prevent unintended exposure of a baby to a medicine during pregnancy.
  • if a woman becomes or wishes to become pregnant, she should be offered information about the risks and benefits to her and her pregnancy of continuing treatment, of moving to an alternative treatment, or of stopping treatment altogether. The risks to the baby of exposure before a woman knew she was pregnant should be discussed.
  • women should not stop using prescribed medication without seeking specialist advice.

Information about whether a medicine must be avoided during pregnancy is available in the patient leaflet that accompanies a medicine.

Our Drug Safety Update gives information for healthcare professionals on safety issues for medicines in pregnancy.

Contraception

If a woman is taking a medicine that is known to be harmful in pregnancy, she should be advised to avoid pregnancy during treatment. This involves using the most effective contraceptive method for her personal circumstances. A doctor, family planning nurse or clinic can advise on the most effective contraceptive methods. This includes the advantages and risks with each method.

Contraceptive methods do sometimes fail and unplanned pregnancies do occur. Performing a pregnancy test before each prescription is one way to avoid unintended exposure to a medicine that may be harmful.

See our guidance for healthcare professionals on frequency of pregnancy testing before and during treatment, depending on the chosen contraceptive method.

Pregnancy Prevention Programmes (PPP)

For some of the most harmful medicines, and where there is a high risk of unintended exposures, specific requirements may be in place to underline the need to avoid use in pregnancy.

A Pregnancy Prevention Programmes is a formal agreement between the patient and their doctor. It makes sure the patient understands the risks to the baby and knows how they should avoid becoming pregnant while on that medicine.

Examples include:

2. Medicines in breastfeeding

Breastfeeding has long-term health benefits for both the mother and her baby.

Some medicines can pass from women through breastmilk to their baby. Only small amounts of the medicine usually reach the baby and most medicines can be used while breastfeeding. For some medicines, this may mean the baby should be monitored more often to make sure they are not harmed by the medicine whilst they are breastfed.

Advice for patients

  • If you regularly take a medicine or have taken one during the late stages of your pregnancy, it is best to plan ahead. Talk to your doctor, nurse, or midwife about your breastfeeding options.
  • Do not stop taking prescribed medicines without talking to your doctor.
  • If you need to take a medicine for the first time, talk to your doctor, nurse, or midwife about how you can safely breastfeed your baby.

Information about when a medicine must be avoided whilst breastfeeding is available in the patient leaflet that accompanies a medicine.

Further information on breastfeeding and on use of medicines during breastfeeding is available from the following websites:

For patients:

For healthcare professionals:

3. Report a side effect of a medicine during pregnancy or breastfeeding

We work with medicine manufacturers to increase knowledge about the use of medicines during pregnancy and breastfeeding. However, there are still gaps in how much we know about their effects.

Reporting any side effects during pregnancy and breastfeeding, including any suspected miscarriage or harm to the baby, helps to increase the information available to everyone about the safety of medicines.

How and why to report an adverse reaction

4. Additional resources for clinicians and researchers

Importance of pharmacokinetic data in pregnancy and lactation

The level of a medicine in the blood depends on its pharmacokinetics (ie the kinetics of drug movement in the body). This describes how quickly a medicine moves into (absorption), within (distribution) and leaves (elimination) the body.

Changes in a woman’s body during pregnancy can change how quickly a medicine is distributed and eliminated from her body, which can affect how well the medicine works. By using pharmacokinetic (PK) data of changes in blood levels of the medicine during pregnancy, it is possible to estimate whether dose changes are needed to maintain the mother’s and/or her baby’s health during pregnancy.

Our PK activities

We run a one day course on Pharmacokinetics of medicines in pregnancy for clinicians who treat women needing to take medication during pregnancy.

The next course will be held on Monday 31st October 2022, please register your interest in this or future events here.

We are currently undertaking a project to predict changes in blood levels of medicines during pregnancy and how these may be used to inform when dose changes are needed and in the development of new medicines (see our blogpost for more information on Physiologically based pharmacokinetic (PBPK) modelling)

Other resources

Download Yellow card campaign animations on reporting in pregnancy

5. Guidance to developers of new medicines

This section provides links to current EU guidance related to use of medicines during pregnancy and breastfeeding:

6. Safer Medicines in Pregnancy and Breastfeeding Information Consortium

The Safer Medicines in Pregnancy and Breastfeeding Information Consortium brings together 16 leading organisations under a common pledge to meet the information needs of pregnant and breastfeeding women and healthcare professionals, through accessible, clear and consistent advice.

The partnership spans the NHS, regulators, and leading third sector and charitable organisations.

The Consortium has agreed an information strategy that sets out how it will work together.

Together, the group will develop a long-term programme of work to improve information provision for women who are thinking about becoming pregnant, are pregnant, or are breastfeeding.

How you can help improve information

Healthcare professionals are asked to report important inconsistencies in UK advice on use on individual or classes of medicines in pregnancy or breastfeeding to the Consortium’s email address safermeds@mhra.gov.uk.

The name of the medicine(s) concerned should be included in the subject line and details of the inconsistency and sources of advice included in the email body.

To report suspected side effects with medicines or adverse events with medical devices, including those experienced by the mother or baby during pregnancy or breastfeeding, please report to the Yellow Card scheme.

7. News and other information

We are working in a number of different areas to improve the knowledgebase for use of medicines in pregnancy and lactation. The following links provide more detailed information:

Published 11 January 2021
Last updated 10 August 2022 + show all updates

  1. Added info for October 2022, one day course on Pharmacokinetics of medicines in pregnancy.

  2. First published.

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