Metal-on-metal hip joints

(Date: October 2022. Version: 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.

Quick read

Metal-on-metal (MOM) hip joints are unlikely to affect a pregnancy. Women with an MOM hip who are planning a pregnancy should speak to their doctor.

What are they?

Metal-on-metal (MOM) artificial hip joints (also called MOM hip implants) are made of cobalt or chromium. MOM implants are rarely used because they wear out more quickly than other types of hip joint.

Are there any concerns about a metal-on-metal hip joint affecting a pregnancy?

People with an MOM hip joint sometimes have increased blood levels of cobalt or chromium, particularly in the first few months after surgery, or if the hip is wearing out.

Increased blood metal levels do not usually cause ill health, but it is unclear whether they might affect a developing baby during pregnancy.

The available information does not suggest that pregnant women with MOM hip joints are at increased risk of having a baby with a birth defect, or other pregnancy problems. However, there is only a small amount of available information as MOM hip joints are rare in women of childbearing age. Because the majority of people with MOM joints have normal blood metal levels, there is no information on pregnancy outcomes specifically in women with high levels of cobalt or chromium.

What if I have a metal-on-metal hip joint and want to get pregnant?

Women with an MOM hip joint who are planning a pregnancy should speak to their GP. The doctor will assess the risk of high metal levels by considering how long the hip joint has been in place and asking about symptoms that could suggest the joint is wearing out. They will check when blood metal levels were last measured and may arrange blood tests. Women may also be referred to a specialist doctor for further monitoring.

Many women will be advised that their hip joint is unlikely to affect a pregnancy.

If high blood metal levels are detected and the joint was implanted recently, a doctor may advise that, where possible, conception is delayed for up to two years after the hip replacement to allow the metal levels to naturally settle. Repeat blood tests might be offered during this period.

If metal levels are high because a hip joint is failing, a specialist might advise further tests and possibly surgery to implant a different type of hip joint. Metal levels will drop once the MOM hip is removed.

In practice, some women may not want to delay pregnancy while waiting for high blood metal levels to drop. The doctor or specialist will be help with weighing up the benefits and possible risks of delaying conception compared to attempting to conceive sooner.

If I become pregnant with a metal-on-metal hip joint, will my baby need extra monitoring during pregnancy?

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

The majority of women with an MOM hip joint in place during pregnancy will not require any extra scans. However, additional checks of the baby might be offered to pregnant women with high blood metal levels.

Are there any risks to my baby if the father has a metal-on-metal hip?

There is no evidence that metal from an MOM hip joint can affect the sperm and therefore cause problems in the baby.

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

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

Our online reporting system allows women with a current or previous pregnancy to create a digitally secure ‘my bumps record’. You will be asked to enter information about your health, whether or not you take any medicines, and your pregnancy outcome. 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 to register.

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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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