Depressive symptom trajectories and their relation to body mass index in women of child-bearing age: The Korea Nurses' Health Study

Background: This study investigated the sub-trajectory groups of depressive symptoms in women of child-bearing age and the factors impacting latent class membership. Moreover, differences in body mass index (BMI) as an outcome variable were identified among the sub-trajectory groups. Methods: Data from the Korea Nurses' Health Study (KNHS) were analyzed, comprising that from 6,918 participants who filled out surveys during modules 1, 5, and 7. The growth mixture model with individually varying observation times was used to identify latent subgroups of depressive symptom trajectories. Results: Three classes of depressive symptom trajectories were identified: increasing over time, stable/low, and decreasing over time. Older participants had a higher probability of belonging to the stable/low class. Married participants were more likely to belong to the stable/low class than to the increasing over time class or decreasing over time class. Participants who worked shifts had a higher chance of belonging to the decreasing over time class than the stable/low class. There was a significant difference between mean BMI across latent classes in module 1 (chi 2(df = 2, N = 6918) = 155.16, p < 0.001) and in module 7 (chi 2(df = 2, N = 6918) = 149.68, p < 0.001). Limitations: The findings of this study should not be generalized to all women of childbearing age, because the study population only included nurses. Conclusions: The results suggest that interventions designed to manage depressive symptoms in women who are younger, unmarried, and who perform shift work may be beneficial. This study identified a relationship between increasing severity of depressive symptoms and increasing BMI.