(Date of issue: August 2016. Version: 2.1)
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?
Fluoxetine (Prozac®, Oxactin®, Prozep®, Olena®, Prozit®) belongs to a group of antidepressants called Selective Serotonin Reuptake Inhibitors (SSRIs) that alter the levels of a chemical in the brain called serotonin. Fluoxetine is used to treat depression, obsessive-compulsive disorder, and bulimia.
Is it safe to take fluoxetine in pregnancy?
There is no ‘yes’ or ‘no’ answer to this question. When deciding whether or not to take fluoxetine during pregnancy it is important to weigh up how necessary fluoxetine is to your health, against the possible risks to you or your baby, some of which will depend on how many weeks pregnant you are. Remaining well is particularly important during pregnancy and while caring for a baby. For some women, treatment with fluoxetine in pregnancy may be necessary.
This leaflet summarises the scientific studies relating to the effects of fluoxetine on a baby in the womb. It is advisable to consider this information before taking fluoxetine if you are pregnant.
Your doctor is the best person to help you decide what is right for you and your baby.
What if I have already taken fluoxetine during pregnancy?
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 if so, to make sure that you are taking the lowest dose that works and only for as long as you need to.
It is very important that you do not suddenly stop taking fluoxetine as this could be dangerous to you, and also to your unborn baby if you are pregnant. Do not make any change to your medication without first talking to your doctor.
Can taking fluoxetine in pregnancy cause birth defects in the baby?
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.
It is not yet clear whether taking fluoxetine during early pregnancy increases the chance of having a baby with a heart defect. It is known that about one in every 100 babies is born with a heart defect, regardless of whether their mother took any medicines during pregnancy. This is called the “background population risk”. Seventeen studies of woman who took fluoxetine in early pregnancy have been carried out since 2005, and while three of these studies show an increased risk of having a baby with a heart defect, the rest do not.
The available information suggests that even if taking fluoxetine during early pregnancy increases the risk of having a baby with a heart defect, nearly all women who take fluoxetine will have a baby with a normal heart. For example, one large study that analysed the data from many of the different studies described above, found that fewer than two in every 100 women who took fluoxetine in pregnancy had a baby with a heart defect. In other words, 98 out of 100 babies did not have a heart defect.
Heart defects have also been shown to occur slightly more frequently in babies of mothers who took SSRIs other than fluoxetine in the first trimester of pregnancy. Although this may be because all SSRIs affect some babies’ heart development in a similar way, it is also possible that there is another reason not related to SSRIs directly that explains why babies of women who take antidepressants in pregnancy are more likely to be diagnosed with a heart defect. For example, babies who were exposed to an SSRI in the womb may be more likely to have their heart checked than babies of women who did not use SSRIs. This could result in small heart defects that would otherwise go unnoticed and not cause any problem to the baby’s health being recorded in one group of babies but not in the other group.
Other birth defects
A small number of studies have suggested possible links between taking fluoxetine in early pregnancy and other specific birth defects (malformations). However, these studies (detailed below) do not provide enough evidence to prove that fluoxetine causes any of these birth defects:
• Two studies suggested that fluoxetine use in early pregnancy increased the likelihood of having a baby with craniosynostosis (where the baby’s skull bones fuse too early, causing an abnormally shaped head and other problems), but one further study did not agree with this finding
• One study indicated that babies born to women who took fluoxetine in early pregnancy were more likely to have malformations of the digestive system, but this was not found in another four studies.
• One study suggested that babies whose mothers had taken fluoxetine during early pregnancy were more likely to have malformations of the ear, face and neck, but this was not found in another study.
• One study suggested that babies whose mothers had taken fluoxetine during early pregnancy were more likely to have a malformation of the kidney called renal dysplasia. No other studies have investigated the likelihood of renal dysplasia in babies exposed in the womb to fluoxetine.
More research is needed to assess whether taking fluoxetine in pregnancy increases the chance of birth defects in the baby.
Can taking fluoxetine in pregnancy cause miscarriage?
No increased risk of miscarriage was shown in any of the five studies of women who took fluoxetine in pregnancy which investigated this.
Can taking fluoxetine in pregnancy cause preterm birth?
There is no strong evidence that taking fluoxetine during pregnancy causes a woman to give birth early (before 37 weeks of pregnancy). While one study showed that women who took fluoxetine after week 25 of pregnancy were at increased risk of having a pre-term birth, three further studies showed no link between fluoxetine use in pregnancy and premature delivery.
Although a number of studies of women taking any SSRI during pregnancy have shown links with premature delivery, we do not know how this relates to women specifically taking fluoxetine. It is also thought that other factors, including other medicines used by the mother and the effect of the medical conditions that women were taking SSRIs to treat, may explain why more of these women gave birth early. It is therefore still not clear whether SSRI use in pregnancy causes preterm birth.
Can taking fluoxetine in pregnancy cause my baby to be small at birth (low birth weight)?
Three studies have all suggested that there may be a link between taking fluoxetine during pregnancy and the baby being slightly smaller at birth. However, most studies which have analysed information from pregnant women taking any SSRI do not show a link with having a smaller baby. It is not yet clear whether fluoxetine affects a baby’s growth in the womb or whether other factors, such as the health of the women studied, might explain why their babies were slightly smaller on average at birth.
Can taking fluoxetine in pregnancy cause stillbirth?
No increased risk of stillbirth was seen in any of the four studies which investigated this. However because only small numbers of women have been studied, more information needs to be collected on this subject.
Can taking fluoxetine in pregnancy cause other health problems in the child?
Withdrawal symptoms at birth (‘neonatal withdrawal’)
Withdrawal symptoms are thought to occur as a result of the newborn baby’s body having to adapt to suddenly no longer getting certain types of medicines through the placenta.
Studies have shown that babies who were exposed to any SSRI in the womb may suffer from neonatal withdrawal. A small number of studies which analysed information for fluoxetine separately showed that babies whose mothers took fluoxetine around the time of delivery may also suffer from neonatal withdrawal. Close monitoring of your baby for a few days after birth may be advised if you have taken fluoxetine regularly in the weeks before delivery.
Persistant 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. PPHN only affects around 1 or 2 out of every 1000 newborn babies but can be serious.
Some studies show that PPHN is more common in babies of women who took an SSRI in pregnancy. These studies suggest that up to one out of every 300 babies whose mothers took an SSRI during later pregnancy (after 20 weeks) may develop PPHN.
Learning and behavioural problems
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.
Because SSRIs alter levels of certain chemicals in the brain, there are concerns that use in pregnancy may affect the baby’s brain development. A number of studies have been carried out to look at whether there is an increased risk of learning and behavioural problems including autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) in children who were exposed to fluoxetine and other SSRIs while in the womb.
None of the four studies that specifically examined children of women who took fluoxetine during pregnancy showed an increased risk of learning and behavioural problems. However, because only a small number of children were studied, and because the children were only assessed up to a maximum of six years of age, it is not yet possible to say for certain that fluoxetine does not affect learning or behaviour.
Many more studies have looked at the development, behaviour, and learning of groups of children whose mothers took any of the SSRIs during pregnancy. These studies are summarised below:
• Autism spectrum disorder (ASD) - Seven studies have investigated whether taking SSRIs during pregnancy is linked to having a child with ASD. Six of these studies found that the chance of having a child with ASD was increased, with some suggesting that ASD rates are approximately doubled in children exposed in the womb to an SSRI, compared to unexposed children. It is important to remember that around one in every 100 children develop ASD, regardless of whether their mother took any medicines in pregnancy. This is called the ‘background population risk’. These studies suggest that 2-3 out of every 100 children exposed to SSRIs in the womb may develop ASD. In other words, 97-98 out of every 100 children of women who took SSRIs in pregnancy will not have ASD.
• Attention defecit hyperactivity disorder (ADHD) – None o the three large studies that have investigated whether taking SSRIs during pregnancy is linked to having a child with ADHD, have shown convincing evidence of a link. Further research into this subject is, however, required.
• Learning and thinking skills - Seven studies compared learning and thinking skills of children who were exposed to SSRIs in the womb with children not exposed to SSRIs. While four of these studies showed no clear differences, two studies did see some differences. However, studies of learning and thinking skills in children are very difficult to carry out and may not produce reliable results if too few children are studied. More research is needed before we can say whether children exposed to SSRIs in the womb may be more likely to have problems with learning and thinking skills.
• Movement problems - Eleven studies have investigated whether children who were exposed to SSRIs in the womb have different ‘motor development’ (as a result of effects on the way that the brain controls movement) than children not exposed to SSRIs. Nine of these studies showed that the motor development of children whose mothers had taken SSRIs during pregnancy was slightly poorer. However, in many of these studies, the children were only observed for the first few weeks of life, so we do not know whether any differences remain as the children get older. More research is required into motor development in children whose mothers were taking SSRIs during pregnancy.
Scientific studies have also suggested that having untreated depression during pregnancy may increase the risk of learning and behavioural problems, including ASD and lower IQ in the child. This is thought to be a result of the effects that depression may have on how a mother is able to interact with her baby. Much more research is therefore required before we can say whether the differences in learning and behaviour described in some of these studies are linked to the SSRI use in pregnancy, to the mother’s illness, or to a combination of both these (or other) factors.
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. Taking fluoxetine in pregnancy would not normally require extra monitoring of your baby.
Are there any risks to my baby if the father has taken fluoxetine?
We would not expect any increased risk to your baby if its father took fluoxetine before, or at 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.