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Date of issue: October 2019, Version: 3

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A corresponding patient information leaflet on USE OF OLANZAPINE IN PREGNANCY is available.

Olanzapine is an atypical antipsychotic (AAP) used in the treatment of schizophrenia, manic episodes and recurrence in bipolar disorder. 

Congenital malformation rates specifically following olanzapine exposure have been statistically analysed in a collective total of ~2,500 pregnancies. There is currently no indication of an increased risk of major congenital malformation or of heart defects specifically. Rates of other specific malformation subtypes have not been statistically assessed. Miscarriage rates following first trimester olanzapine exposure have been quantified in a collective total of just 223 women. While there is currently no evidence of an association with olanzapine exposure, larger studies are required to confirm this finding. Data relating to other pregnancy outcomes following maternal olanzapine exposure are either extremely limited or are absent, thus precluding evidence-based risk assessments.

Studies of antipsychotics (APs)/AAPs as therapeutic classes that include a collective total of >13,600 exposures do not raise concerns of adverse pregnancy outcomes directly related to use. Although findings relating to stillbirth and preterm delivery rates are conflicting, the studies reporting positive findings for these outcomes were not adequately controlled and further research is therefore required to confirm or refute these associations. Neurodevelopmental outcomes following in utero exposure to APs have not been sufficiently studied to permit any assessment of risk.

In the non-pregnant population, use of AAPs (particularly olanzapine and clozapine) is a risk factor for impaired glucose homeostasis and type 2 diabetes. There are therefore concerns of an increased risk of maternal gestational diabetes mellitus (GDM) and its sequelae following gestational olanzapine use, and the two studies that assessed GDM rates following specific olanzapine exposure suggest a possible association. An increased risk of fetal macrosomia following gestational exposure to olanzapine is therefore also possible.

Use of olanzapine and other APs throughout pregnancy or near delivery has been associated with withdrawal symptoms in the neonate and/or poor neonatal adaptation syndrome (PNAS). These symptoms are likely to be more severe in infants exposed in utero to more than one CNS acting drug. Delivery should therefore be planned in a unit with neonatal intensive care facilities.

It is important to ensure that maternal mental health conditions are treated appropriately. Where a woman’s illness is well-controlled on olanzapine, either prior to conception or during pregnancy, the risk of discontinuing or changing medication, or reducing the dose, should be carefully weighed against the risk of relapse. Where clinically appropriate, clinicians are encouraged to discuss the advantages and disadvantages of continued olanzapine use during pregnancy with the patient. Where the benefit of continued treatment is considered to outweigh any potential or known risks, olanzapine may be prescribed for use in pregnancy.

This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to NHS health care professionals who are logged in.

If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.

If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.

Disclaimer: Every effort has been made to ensure that this monograph was accurate and up-to-date at the time of writing, however it cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes of the measures recommended. The final decision regarding which treatment is used for an individual patient remains the clinical responsibility of the prescriber. This material may be freely reproduced for education and not for profit purposes within the UK National Health Service, however no linking to this website or reproduction by or for commercial organisations is permitted without the express written permission of this service. This document is regularly reviewed and updated. Only use UKTIS monographs downloaded directly from to ensure you are using the most up-to-date version.