(Date: July 2014. 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 is it?

Diclofenac (Defenac®, Diclofex®, Diclozip®, Diclomax®, Econac®, Fenactol®, Flamatak®, Flamrase®, Flexotard®, Motifene®, Rheumatac®, Rhumalgan®, Slofenac®, Volsaid®, Voltarol®) is a non-steroidal anti-inflammatory drug (NSAID) that is prescribed to treat pain (for example, following an operation). It is also used in the management of rheumatoid arthritis and gout. Diclofenac is available as a tablet and as a gel which is applied to the skin. This leaflet summarises the scientific studies relating to the effects of diclofenac on a baby in the womb.

Is it safe to use diclofenac in pregnancy?

Use of diclofenac during pregnancy is not advised unless prescribed by your doctor, especially if you are 30 or more weeks pregnant. For some women with certain illnesses, diclofenac may be prescribed before 30 weeks of pregnancy. For most women paracetamol is usually recommended to control pain during pregnancy. If paracetamol does not control your pain it is important that you ask your doctor for advice before taking diclofenac or any other NSAID. Diclofenac in gel form that is applied to the skin can enter the bloodstream and is therefore also not recommended for use in pregnancy unless under medical supervision. Your doctor is the best person to help you decide what is right for you and your baby.

This leaflet summarises the scientific studies relating to the effects of diclofenac on a baby in the womb. It is advisable to consider this information before taking diclofenac if you are pregnant.

What if I have already used diclofenac during pregnancy?

There is no strong scientific proof that using diclofenac before week 30 of pregnancy will harm a baby in the womb. However, if you have taken or are taking any medicines, it is always a good idea to let your doctor know that you are pregnant so that you can decide together whether you still need the medicines that you are on and to make sure that you are taking the lowest dose that works.

If you have used diclofenac after week 30 of pregnancy it is important that you let your doctor or midwife know straight away as your baby’s wellbeing in the womb will need to be assessed. 

Can using diclofenac in pregnancy cause miscarriage?

It is unclear whether using diclofenac in early pregnancy increases the chance of having a miscarriage. While one study has shown an increased risk of miscarriage in pregnant women taking diclofenac, two further studies have not agreed with this finding. Some studies have shown that women who take any NSAID during pregnancy are more likely to have a miscarriage than women who have not.
However, women with certain illnesses, such as rheumatoid arthritis, are more likely to need to take diclofenac and other NSAIDs in pregnancy. These illnesses are themselves thought to increase a woman’s chance of having a miscarriage. More research is therefore needed to understand whether the increased risk of miscarriage reported in some of the above studies is due to the NSAIDs, the illnesses that women may need to take NSAIDs for in pregnancy, or a combination of both factors. More information needs to be collected from women taking diclofenac during pregnancy.

Can using diclofenac 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.

Three studies have all shown that women taking diclofenac during early pregnancy were no more likely to have a baby with a birth defect than women not taking diclofenac.

Most studies of groups of women who took any type of NSAID during the first three months of pregnancy have not shown that these women were more likely to have a baby with a birth defect than women who didn’t take NSAIDs. A small number of studies have suggested possible links between taking NSAIDs in early pregnancy and various specific birth defects. However, none of these studies provide enough evidence to prove that NSAIDs cause any type of birth defect. Diclofenac might also affect an unborn baby differently to other NSAIDs. More information needs to be collected about pregnant women specifically taking diclofenac.

What problems can using diclofenac after 30 weeks of pregnancy cause in my baby?

Premature closure of the ductus arteriosus
Before birth, a blood vessel in the baby called the ductus arteriosus needs to stay open to supply the baby in the womb with nutrients and oxygen from the mother. The ductus arteriosus closes just after birth to allow the baby’s blood to flow through its lungs once it starts breathing. Premature closure of the ductus arteriosus is the medical term used to describe this blood vessel closing before it is supposed to.

Use of diclofenac or other NSAIDs after 30 weeks of pregnancy can cause the ductus arteriosus to close while the baby is still in the womb, and the baby may then need to be delivered early. It is therefore important to contact your doctor or midwife straight away if you have taken any NSAID after 30 weeks of pregnancy, especially if you have taken several doses or more than the recommended dose.

Persistent pulmonary hypertension of the newborn (PPHN)
PPHN or persistent pulmonary hypertension of the newborn occurs when a newborn baby’s lungs do not adapt to breathing outside the womb. It is thought to be linked, in some cases, to early closure of the ductus arteriosus (see above). PPHN only affects around 1 or 2 out of every 1,000 newborn babies in the general population but is important as it can be serious.

Although one study has shown a link between PPHN and taking NSAIDs during pregnancy, another study did not show a link. There have, however, been isolated reports of babies exposed to diclofenac in the womb having PPHN.

Oligohydramnios (reduced fluid around the baby)
Use of diclofenac and other NSAIDs after 30 weeks of pregnancy may result in oligohydramnios (where there is too little amniotic fluid in the sac around the baby). Oligohydramnios can cause a number of complications, including:

• The baby’s lungs being under-developed (because inhaling amniotic fluid while in the womb helps to expand and develop the lungs).

• The baby’s bladder being under-developed (because urine expands and develops the bladder).

• The baby’s skull and leg bones being misshapen and the baby having ‘flattened’ facial features (because amniotic fluid ‘cushions’ the baby in the womb).

• Compression (squashing) of the umbilical cord, which may result in reduced blood flow from the mother to the baby in the womb.

If you have used diclofenac after 30 weeks of pregnancy your doctor may wish to check your amniotic fluid levels by ultrasound scan.

Wherever possible, use of diclofenac during the third trimester of pregnancy should be avoided. Please discuss any concerns that you may have with your doctor.

Can using diclofenac in pregnancy cause preterm birth or my baby to be small at birth (low birth weight)?

Two studies have both agreed that women taking diclofenac during pregnancy are no more likely to have a preterm birth (before 37 weeks of pregnancy) than women not taking diclofenac.

However, one study has provided weak evidence that women taking diclofenac may be more likely to have a low birth weight baby (<2500g) than women not taking diclofenac. Because women taking diclofenac may have underlying illnesses that can cause low birth weight in the baby, we do not know whether the lower birth weights observed in this study were due to the diclofenac itself or to other factors. More research into this subject is therefore required

Studies of groups of pregnant women who took any NSAID have not shown increased risks of preterm birth or low birth weight in the baby.

Can using diclofenac 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.

There is no known link between taking diclofenac in pregnancy and learning or behavioural problems such as attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder in the child. There are, however, no scientific studies that have specifically investigated a link with these problems.

Will my baby need extra monitoring during pregnancy?

Most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects as part of their routine antenatal care. Using diclofenac before 30 weeks of pregnancy would not normally require extra monitoring of your baby.

If you have used diclofenac after 30 weeks of pregnancy you may need extra scans or monitoring of your baby. 

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

We would not expect any increased risk to your baby if the father used diclofenac before or around the time your baby was conceived.

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.



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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