Early Life Environmental Factors and Emotional-Behavioral Problems in South African Children and Adolescents at Age 5...

Accumulating research conducted in high-income countries has reported that early life environmental factors are linked to emotional-behavioral problems. However, approximately 90% of the world's children live in low- and middle-income countries, where research remains limited. We investigated the prospective associations between early life environmental factors and emotional-behavioral problems in South African children and adolescents.

Data were drawn from the Safe Passage Study, a population-derived birth cohort (5,889 mother-infant dyads). Early life environmental factors (pre-, peri-, and postnatal) were collected by questionnaires, clinical assessments, and medical records at inception. In this Biomarkers of Neurodevelopmental Outcomes (BONO) study follow-up, emotional-behavioral problems (externalizing and internalizing problems) were measured once using caregiver-reported Strengths and Difficulties Questionnaire at age 5 to 16 years (n = 1,284). Associations were examined using regression models adjusted for the child's or adolescent's sex and age at assessment.

Of the 104 early life environmental factors, prenatal factors associated with both increased externalizing and internalizing problems were maternal mental health: namely, self-harm (externalizing problems: beta coefficient (β) = 0.69; internalizing problems: β = 0.60), depression (externalizing problems: β = 0.06, internalizing problems: β = 0.08), anxiety (externalizing problems: β = 0.05; internalizing problems: β = 0.04), and infections (externalizing problems: β = 0.65; internalizing problems: β = 0.45). Factors associated only with externalizing problems included prenatal maternal substance use, asthma, paternal education, and infant secondhand smoke exposure. Enlarged placenta was associated with internalizing problems. Fetal, birth, and other placental factors showed modest associations.

In this South African setting, prenatal maternal mental health and infections emerged as consistent risk factors for both externalizing and internalizing problems. Future studies are needed to elucidate the impact of co-occurring early life environmental factors and to investigate the mechanisms through which these early life environmental factors contribute to the emergence of emotional-behavioral problems.