bumps - best use of medicine in pregnancy

Metal-on-metal hip joints

(Date: October 2017. Version: 2)

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 are they?

Metal-on-metal (MOM) artificial hip joints (made of cobalt or chromium) may be used to replace a diseased or damaged hip joint.

Is it safe to become pregnant if I have had a metal-on-metal hip replacement?

In the months following MOM hip replacement surgery the levels of cobalt and chromium in a person’s blood may be increased. Although this increase does not usually cause toxicity in the individual receiving the artificial hip, possible effects on an unborn baby have not been studied. As a precaution it is therefore often recommended that a woman either completes any pregnancies before undergoing MOM hip replacement or waits for two years after surgery before attempting to conceive. In all people who have received MOM hip joints, monitoring of blood levels of cobalt and chromium will be offered for at least the first five years following surgery, or after this period if the hip joint shows signs of failing. Women who are planning to conceive are advised to discuss any elevation of cobalt or chromium levels with their doctor before trying to become pregnant.

Can having a metal-on-metal hip replacement 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.

No large studies have investigated the chance of birth defects in babies born to women with an MOM hip joint in place during pregnancy. However, a report of 35 babies born in the same hospital, whose mothers had MOM hips provides some reassurance and does not indicate a higher than expected chance of birth defects. Large studies are ideally required to confirm this finding.

Can having a metal-on-metal hip replacement cause miscarriage?

No large studies have investigated the chance of miscarriage in women with an MOM hip joint. However, a report detailing 17 pregnancies in women with MOM hips does not suggest that they have a greater chance of miscarriage than women in the background population. Further research is required to confirm this finding.

Can having a metal-on-metal hip replacement cause stillbirth?

There is no information in the scientific literature about the chance of stillbirth in women with MOM hip replacements.

Can having a metal-on-metal hip replacement cause preterm birth or my baby to be small at birth (low birth weight)?

No large studies have investigated the chance of preterm birth in women with an MOM hip joint. However, a report of 14 pregnancies in women with MOM hips does not suggest that this affects the chance of preterm birth. Further research is required to confirm this finding. There is no information in the scientific literature about the chance of low birth weight in babies born to women with MOM hip replacements.

Can having a metal-on-metal hip replacement 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 large studies have investigated learning and behaviour in children born to women with an MOM hip joint. However, a report of 14 children born to women with MOM hips does not suggest that these children have a greater chance of autism, attention deficit hyperactivity disorder, or a learning disability compared to children in the background population. The children were assessed at between 10 months and 10 years of age. A further case report described normal development up to nine weeks of age in a baby born to a mother with abnormally high cobalt and chromium levels from an MOM hip joint. Large well-designed studies that assess learning and development in children whose mothers had an MOM hip joint in place during pregnancy are required to confirm these findings.

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 having an MOM hip joint in place during pregnancy causes any problems that would require extra monitoring of your baby.

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

We would not expect any increased risk to your baby if the father had an MOM hip in place 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 www.uktis.org.

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.

   

www.medicinesinpregnancy.org

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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