Mood instability across the perinatal period: A cross-sectional and longitudinal study

Background: As a trans-diagnostic concept, mood instability (MI) is significantly linked to a variety of psychiatric disorders in general and clinical samples. However, there is limited research on perinatal MI, even though perinatal women experience an elevated level of MI. In this study, we examined the relationship between perinatal MI and its risk factors, the association between antenatal MI and postpartum depression (PPD), and the trajectory of perinatal MI. Methods: A total of 648 women participated in this longitudinal study at three points: T1 (17.4 ± 4.9 weeks pregnant), T2 (30.6 ± 2.7 weeks pregnant), and T3 (4.2 ± 2.1 weeks postpartum). Linear regression was used to examine MI and its risk factors, hierarchical multiple regression was utilized to investigate the relationship between antenatal MI and PPD, and a linear mixed model was employed to examine the trajectory of perinatal MI over T1-T3. Results: Perinatal depression, history of depression, and stress at T1, T2, and T3, and labor/birth complications at T3 were significant risk factors for MI. MI at T1 was associated with PPD after controlling for important confounders at T1. The trajectory of perinatal MI had a declined trend from early pregnancy to postpartum. Limitations: The participants were predominantly Caucasian and with post-secondary education, which may limit the generalization of our findings. A lack of research on perinatal MI limited our ability to discuss the topic in relation to existing literature. Conclusions: This study expands our understanding of MI in perinatal women, and indicates that more research is needed.