Olanzapine

What is it?

Olanzapine (Zalasta^®, Zyprexa^®) belongs to a group of medicines called atypical antipsychotics and is used to treat schizophrenia, mania, and to prevent recurrence of bipolar disorder.

Is it safe to take olanzapine in pregnancy?

When deciding whether or not to take olanzapine during pregnancy it is important to weigh up the potential benefits to your health and wellbeing against the possible risks to you or your baby, some of which will depend on how many weeks pregnant you are. During pregnancy, psychiatric illness can sometimes occur for the first time, or may get worse. For some women, treatment with an antipsychotic such as olanzapine may be offered by a specialist so that they have the best chance of remaining well.

What if I have already taken olanzapine 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 olanzapine as this could be dangerous. Do not make any changes to your medication without first talking to your doctor.

Can taking olanzapine 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.

A total of around 3,000 pregnant women taking olanzapine have been studied. There is currently no suggestion of any link between olanzapine use in pregnancy and general birth defects in the baby.

Additionally, one large study found that babies born to women taking olanzapine were no more likely to have a heart defect than babies born to women not taking olanzapine.

Studies of over 10,000 women who used any type of antipsychotic during pregnancy also do not collectively raise alarm of a link with birth defects.

Can taking olanzapine in pregnancy cause miscarriage?

One small study of 223 women who took olanzapine in pregnancy did not find that they had a higher chance of miscarriage compared to women not taking olanzapine.

Studies of around 3,000 women who used any type of antipsychotic during pregnancy do not raise concern of a direct link with miscarriage. While this is reassuring, further studies of women specifically taking olanzapine are ideally required.

Can taking olanzapine in pregnancy cause stillbirth?

One study of 610 women who had taken olanzapine in pregnancy found that they did not have a higher chance of stillbirth than women in the background population.

Studies of stillbirth in pregnant women taking any antipsychotic have produced mixed findings, with three studies finding no link but one large study finding a possible link. Further studies of women specifically taking olanzapine are required before definite conclusions can be drawn.

Can taking olanzapine in pregnancy cause preterm birth?

One study of 610 women who had taken olanzapine in pregnancy found that they did not have a higher chance of preterm delivery than women in the background population.

Some (but not all) studies of pregnant women taking any antipsychotic have shown a possible link with preterm delivery, but it is thought that lifestyle factors in pregnant women taking antipsychotics are likely to have contributed to this finding. Because there is only one study of women specifically taking olanzapine, more information on this subject is needed.

Can taking olanzapine in pregnancy affect a baby’s growth in the womb and his/her birth weight?

Low birth weight
No studies have investigated whether olanzapine use in pregnancy might affect a baby’s birth weight. Studies of pregnant women taking any antipsychotic do not overall raise alarm that their use slows the baby’s growth in the womb. Information about women specifically taking olanzapine ideally needs to be collected.

Increased birth weight
Weight gain, high blood sugar and diabetes are common side effects of antipsychotic use in non-pregnant individuals. If these problems occur in pregnancy they can in turn cause increased growth of a baby in the womb. Some studies, but not others, have found a possible link between antipsychotic use in pregnancy and having a large baby. However, no studies have yet investigated whether babies born to women specifically taking olanzapine are more prone to having a high birth weight.

Can taking olanzapine in pregnancy cause other health problems in the child?

Withdrawal symptoms at birth (neonatal withdrawal)
Withdrawal symptoms are thought to occur as the newborn baby’s body has to adapt to suddenly no longer getting certain types of medicines through the placenta.

Taking olanzapine and other antipsychotics during pregnancy can lead to neonatal withdrawal. Close monitoring of your baby for a few days after birth may therefore be advised if you have taken olanzapine regularly in the weeks before delivery. Your doctor may therefore advise that your baby is delivered at a hospital with facilities to provide this care.

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.

No studies have investigated learning and behaviour in children exposed in the womb to olanzapine.

Will my baby need extra monitoring?

Most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects and check their baby’s growth as part of their routine antenatal care. Taking olanzapine in pregnancy would not normally require extra monitoring of your baby. 

Weight gain and increased blood sugar (hyperglycaemia) can be side effects of olanzapine. If you are taking olanzapine during pregnancy and are gaining more weight than expected, or have higher than expected levels of sugar in your urine, your doctor may offer you a glucose tolerance test to measure how your body responds to sugar.

If you have taken olanzapine around the time of delivery your baby may require extra monitoring after birth because of the possible risk of neonatal withdrawal.

Are there any risks to my baby if the father has taken olanzapine?

We would not expect any increased risk to your baby if the father took olanzapine before or 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.