HSRAANZ 2019 Awards – Best Paper by an Early Career Researcher – Highly Commended, Andrea Schaffer

Paper summary

Antipsychotic medicines are primarily indicated for schizophrenia and bipolar disorder, but are increasingly being prescribed to treat other conditions such as depression, anxiety, and insomnia. Consequently, antipsychotic use has been increasing both in the general population and in pregnant women. For pregnant women and their health practitioners, the decision to continue using antipsychotics during pregnancy can be complicated. The evidence for harms to the foetus are inconsistent, and abrupt discontinuation of treatment can lead to relapse of mental health problems, with untreated mental illness itself being a risk factor for poor outcomes. It is thus important to understand how and why women are using antipsychotics in pregnancy.

In this study we described antipsychotic use in a cohort of 137,993 women from the Maternal Use of Medications and Safety (MUMS) study who gave birth in New South Wales, and characterised them according to their mental health characteristics and birth outcomes using linked administrative health data (perinatal data, medicine claims data, hospital admissions, and death registry data). We identified 2741 (2.0%) women who were exposed to antipsychotics in the 15 months prior to or during pregnancy. We used group-based trajectory modelling, a statistical method that identifies clusters of similar individuals, to classify these women into six distinct trajectories of antipsychotic use based on duration and dose: in two trajectories, women used low daily doses in the short-term and discontinued prior to or in early pregnancy (51.1%), while three trajectories involved long-term use of low (20.9%), moderate (11.0%), and high (2.0%) daily doses continuing throughout pregnancy. In one trajectory (15.0%), women increased their antipsychotic use during pregnancy.

Overall, compared to women not using antipsychotics, women using antipsychotics had elevated rates of adverse birth outcomes, which is in part related to the observed high rates of risk factors such as smoking and substance use disorder. When we looked at the characteristics of women within the different trajectories, we found that continuation of antipsychotic use through pregnancy correlated with the underlying indication and severity of psychiatric illness. That is, women with long-term and continuous use of antipsychotics were more likely to have a diagnosis of schizophrenia or bipolar disorder, to have been using multiple psychotropic medicines (such as antidepressants, benzodiazepines and anticonvulsants), and to have had a mental health hospitalisation during their pregnancy. Women exposed to the highest doses had the highest rates of certain birth outcomes, such as gestational diabetes, preterm birth, and neonatal abstinence syndrome.

Thus, our study has shown that women using antipsychotic medicines around pregnancy were heterogeneous, with varying mental health needs and complexity of treatment, and high rates of risk factors such as smoking and substance use disorder. It is therefore important that clinical guidance about use of antipsychotics in pregnancy be tailored to a woman's individual circumstances as much as possible.

Schaffer AL, Zoega H, Tran DT, Buckley NA, Pearson A, Havard A. Trajectories of antipsychotic use before and during pregnancy, and associated maternal and birth characteristics. Aust N Z J Psychiatry 2019;53(12):1208-1221.