Background: Today, the first generations of very low birth weight (VLBW ≤ 1500 g) infants are entering adulthood but very little is known of their personality traits, associated with both psychopathological vulnerability and resilience.
Methods: In this cohort study we compared personality traits among young adults (age range 18 to 27 years, mean 21.4, SD 2.19) with VLBW (n = 158) with those of term-born controls (n = 168) of same gender, age, and maternity hospital. The participants completed the Neo-Personality Inventory.
Results: Of the five main traits, the VLBW participants scored significantly higher in conscientiousness (MD .1, 95% CI .0 to .3; p < .03), agreeableness (MD .2, 95% CI .0 to .3; p < .001), and lower in openness to experience (MD –.1, 95% CI –.2 to .0; p < .02). In addition, the VLBW group differed from the controls with regard to facets of neuroticism (lower hostility and impulsivity, ps < .05) and extraversion (less assertiveness p < .01). Furthermore, there were fewer undercontrolled personality profiles among the VLBW subjects (p < .01). All differences were independent of gender, age at assessment, parental education, individual school grade average, and maternal pre-eclampsia and smoking during pregnancy.
Conclusions: Young adults born with VLBW showed markedly different personality traits compared with their controls. The VLBW group displayed less negative emotions, were more dutiful and cautious, and displayed more warmth in their social relationships than their term-born peers. We present two potential mechanisms underlying these findings. The first relates to parental influences and the other to evidence linking biological mechanisms associated with prematurity with personality characteristics in adulthood.