Developmental trajectories of internalizing problems among individuals born very preterm/very low birthweight: early risk and resilience factors.

Individuals born very preterm (VPT; < 32 weeks) or with very low birthweight (VLBW; < 1500 g) are at higher risk for internalizing problems compared to those born at term (37-42 weeks) or with normal birthweight (> 2500 g). However, group-level comparisons often overlook individual differences within these populations. Using data from the Bavarian Longitudinal Study, a German population-based birth cohort, this study aims to investigate developmental trajectories of internalizing problems from childhood to adulthood in 368 VPT/VLBW individuals and to identify early-life neonatal, family, neurodevelopmental, and social factors associated with these trajectories. Growth mixture modeling of parent-reported internalizing problems at ages 6, 8, 13, and 26 revealed three distinct trajectories: 61.7% exhibited consistently low levels of internalizing problems, 21.7% showed increasing problems, and 16.6% showed decreasing problems over time. Compared to the consistently low group, the increasing group had lower socioeconomic status at birth, lower gestational age, and more neurosensory impairments; while the decreasing group was characterized by higher family adversity, greater shyness and emotionality, higher birthweight, and fewer parent-infant relationship problems. Multiple births were associated with a higher likelihood of exhibiting consistently low internalizing problems rather than the increasing or decreasing trajectories. Early interventions targeting higher-risk groups-such as those with lower gestational age, neurosensory impairments, socioeconomic disadvantages, family adversity, or challenging temperaments-and promoting resilience factors like positive parenting, have the potential to improve long-term mental health outcomes for VPT/VLBW individuals.