Background: Parental socioeconomic status is associated with health outcomes across age. However, the specific age-, gender-, and disease-related patterns linking parental income during early childhood to healthcare utilization across age remain poorly characterized. Enhanced understanding of these associations is essential to inform targeted interventions and improve health equity.

Methods: This cross-sectional study analyzed primary care consultations for all Norwegian residents aged 10-59 in 2018 (N = 2,882,669), merged with parental income records from 1958 up until 2017. The analysis was restricted to GP consultations for diseases or disorders, excluding consultations for symptoms and complaints. Analyses were stratified by sex, age, and type of health problem. We also examined how adult income and education mitigate socioeconomic disparities in healthcare utilization.

Results: Individuals from low parental income backgrounds had higher primary care utilization. In the lowest parental income quintile, females averaged 1.89 (SD 3.30) and males 1.24 (SD 2.65) consultations per year, compared to 1.60 (SD 2.94) and 1.00 (SD 2.21), respectively, in the highest quintile. Socioeconomic differences varied by age and disease type. Among females, the largest inequality occurred at age 24, with 1.97 (95% CI 1.89-2.05) consultations in the lowest quintile versus 1.17 (95% CI 1.11-1.23) in the highest. For males, inequality was largest at age 31, with 1.22 (95% CI 1.15-1.30) versus 0.78 (95% CI 0.74-0.83) consultations. Disease-specific differences showed the largest odds ratios for psychological (females: OR 1.54, 95% CI 1.51-1.57; males: OR 1.64, 95% CI 1.60-1.68) and endocrine/nutritional issues (females: OR 1.34, 95% CI 1.32-1.37; males: OR 1.35, 95% CI 1.31-1.38). Adjusting for adult education and income eliminated most disparities, except for musculoskeletal and endocrine/nutritional health problems.

Conclusions: Lower parental income in childhood was associated with higher adult primary care use, particularly for psychological, musculoskeletal, and endocrine conditions, with heterogeneity by age and sex. These associations were attenuated when accounting for individuals’ own education and income, suggesting that policies that enhance educational attainment and economic opportunity can help reduce health inequalities.