Women with schizophrenia frequently discontinue antipsychotic medications during pregnancy. However, evidence on the risk of postpartum relapse associated with antipsychotic use during pregnancy is lacking.

To investigate the within-individual association between antipsychotic continuation during pregnancy and postpartum relapse in women with schizophrenia.

This retrospective cohort study used data of women with schizophrenia who gave live birth between 2007 and 2018 identified from the National Health Information Database of South Korea. Women were classified according to antipsychotic use patterns during the 12 months before delivery as non-users, discontinuers and continuers. Relapse was defined as admission for psychosis (ICD-10, F20–29). The incidence rate ratio (IRR) for admission for psychosis in the 6-month postpartum period was estimated using conditional Poisson regression, with the reference period set between 2 and 1 years before delivery. Additionally, we calculated the relative risk ratios (RRRs) for the IRRs of different antipsychotic use patterns.

Among the 3026 women included in the analysis (median age 34 years, interquartile range 31–37), the within-individual risk of admission for psychosis in the 6-month postpartum period was 0.56 times (RRR, 95% CI 0.36–0.87) lower in continuers (IRR = 1.31, 95% CI 0.89–1.72) than in discontinuers (IRR = 2.34, 95% CI 1.87–2.91). Among discontinuers, the IRRs of admission for psychosis in the 6-month postpartum period did not change significantly with the timing of discontinuation (trend P = 0.946).

Antipsychotic continuation during pregnancy was associated with a reduced risk of postpartum relapse in women with schizophrenia. Continuing antipsychotics during pregnancy would be recommended after a risk–benefit assessment.