Borderline personality traits are differently associated with postpartum psychosis and postpartum depression episodes in women with bipolar disorder.

Women with bipolar disorder have approximately 40 %-50 % chance of having a perinatal bipolar recurrence. Knowing the factors associated will be beneficial for the prediction and prevention of episodes. We aim to establish if borderline personality disorder traits, as measured by the BEST (Borderline Evaluation of Severity over Time) scale, are associated with perinatal psychiatric outcomes. We recruited women with bipolar disorder as part of the BDRN (Bipolar Disorder Research Network) study. Women were interviewed and we collected their demographic and clinical information. Participants subsequently completed the BEST questionnaire. We analysed the association of BEST scores with lifetime presence/absence of perinatal bipolar relapse and, employing multinomial logistic regression, with different subtypes of perinatal outcomes: postpartum psychosis; postpartum depression, and other episodes. In our sample of 807, although there was no significant association between the BEST total score and perinatal episodes as a whole (adjustedOR 1.01 CI95% [0.99, 1.03], p = 0.204), we found significant differing associations with different subtypes of episodes. Women scoring highly on BEST were less likely to experience a postpartum psychotic episode (RRR 0.96 CI95% [0.94, 0.99], p = 0.005) but more likely to experience a non-psychotic depressive episode (RRR 1.03 CI95% [1.01, 1.05], p = 0.007) than no relapse. This study is limited by its cross-sectional design and self-report nature of BEST. In women with bipolar disorder, borderline traits differentiate the risk of postpartum depression and postpartum psychosis, emphasise the importance of considering risk factors for these perinatal episodes separately, and may help individualise the risk for women in the perinatal period. [Abstract copyright: Copyright © 2023. Published by Elsevier B.V.]