Patterns of Exposure to Cumulative Risk Through Age 2 and Associations with Problem Behaviors at Age 4.5: Evidence from Growing Up in New Zealand.

Exposure to cumulative risk (CR) has important implications for child development, yet little is known about how frequency, persistence, and timing of CR exposure during early childhood predict behavioral problems already before school start. We examine prospective longitudinal associations between patterns of CR exposure from third trimester through 2 years and subsequent behavior problems at 4.5 years. In 6156 diverse children in the Growing Up in New Zealand longitudinal study, the presence of 12 risk factors, spanning maternal health, social status, and home and neighborhood environment, defined CR and were assessed at last trimester and 9 months and 2 years of age. At child age 4.5 years, mothers completed the Strengths and Difficulties Questionnaire, where a score ≥ 16 indicated an abnormal level of problem behaviors (ALPB). Children exposed to a CR ≥ 1 at least once in early development, compared to those with consistent CR = 0, showed a significantly higher likelihood of ALPB at 4.5 years. Consistent high exposure to CR ≥ 4 across all three assessments had the highest prevalence (44%) of ALPB at age 4.5. Children with high CR exposure on two of three, compared to on all three, time points in early development did not evidence a significantly reduced prevalence (32%-41%) of ALPB. The common co-occurrence of risk factors and their significant developmental impact when accumulated early in life underscore the need for systematic multisector intervention and policy implementation during pregnancy and shortly after birth to improve outcomes for vulnerable children.