Extremely low birth weight (ELBW) survivors have higher rates of shyness, a risk factor for poorer outcomes across the life span. Due to advances in fetal and neonatal medicine, the first generation of ELBW survivors have survived to adulthood and become parents. However, no studies have investigated the transmission of their stress vulnerability to their offspring. We explored this phenomenon using a population-based cohort of ELBW survivors and normal birth weight (NBW) controls. Using data from three generations, we examined whether the shyness and parenting stress of ELBW and NBW participants (Generation 2) mediated the relation between the parenting style of their parents (Generation 1) and shyness in their offspring (Generation 3), and the extent to which exposure to perinatal adversity (Generation 2) moderated this mediating effect. We found that among ELBW survivors, parenting stress (in Generation 2) mediated the relation between overprotective parenting style in Generation 1 (grandparents) and child shyness in Generation 3. These findings suggest that perinatal adversity and stress may be transmitted to the next generation in humans, as reflected in their perceptions of their children as shy and socially anxious, a personality phenotype that may subsequently place their children at risk of later mental and physical health problems.

In general population samples, better childhood cognitive functioning is associated with decreased risk of depression in adulthood. However, this link has not been examined in extremely low birth weight survivors (ELBW, <1000 g), a group known to have poorer cognition and greater depression risk. This study assessed associations between cognition at age 8 and lifetime risk of major depressive disorder in 84 ELBW survivors and 90 normal birth weight (NBW, ⩾2500 g) individuals up to 29–36 years of age. The Wechsler Intelligence Scale for Children, Revised (WISC-R), Raven’s Coloured Progressive Matrices and the Token Test assessed general, fluid, and verbal intelligence, respectively, at 8 years of age. Lifetime major depressive disorder was assessed using the Mini International Neuropsychiatric Interview at age 29–36 years. Associations were examined using logistic regression adjusted for childhood socioeconomic status, educational attainment, age, sex, and marital status. Neither overall intelligence quotient (IQ) [WISC-R Full-Scale IQ, odds ratios (OR)=0.87, 95% confidence interval (CI)=0.43–1.77], fluid intelligence (WISC-R Performance IQ, OR=0.98, 95% CI=0.48–2.00), nor verbal intelligence (WISC-R Verbal IQ, OR=0.81, 95% CI=0.40–1.63) predicted lifetime major depression in ELBW survivors. However, every standard deviation increase in WISC-R Full-Scale IQ (OR=0.43, 95% CI=0.20–0.92) and Performance IQ (OR=0.46, 95% CI=0.21–0.97), and each one point increase on the Token Test (OR=0.80, 95% CI=0.67–0.94) at age 8 was associated with a reduced risk of lifetime depression in NBW participants. Higher childhood IQ, better fluid intelligence, and greater verbal comprehension in childhood predicted reduced depression risk in NBW adults. Our findings suggest that ELBW survivors may be less protected by superior cognition than NBW individuals.