Beyond single time points: prospective longitudinal maternal depression trajectories shape infant social behavior in the first year.

Maternal depression symptoms are diverse and vary in onset, duration, and severity, and it may affect the infant differently. This study aimed to (1) determine the different trajectories of maternal depression symptoms from late pregnancy to one year postpartum, and (2) examine the relationship between maternal depression trajectories and infant development within the first year of life. In this longitudinal study (N = 218), maternal depression levels were measured using the Edinburgh Postnatal Depression Scale, and latent class growth analysis were used to identify distinct trajectories. Infant behavioral development was evaluated using the Neonatal Behavioral Observation System and the Griffiths Development Scale-Chinese. Generalized estimating equation was used to assess the relationship between maternal depression trajectory and infant behavioral development. We characterized maternal depression trajectories and classified them into three groups: no-, decreased- and increased- depression trajectories. Infants' personal-social scores of the decreased-MD (B = -0.219, 95% CI: -0.360, -0.078) and increased-MD (B = -0.451, 95% CI: -0.640, -0.262) groups were lower than that of the no-MD group at five and twelve months. The increased-MD trajectory group had lower social ability than the decreased-MD group (B= -0.233, 95% CI: -0.424, -0.041). The difference remained significant after adjusting for confounding factors. Our findings show that the severity and trend of maternal depression trajectory are the key factors affecting infants' social behavior development.