Parental mental health, socioeconomic position and the risk of asthma in children—a nationwide Danish register study

BACKGROUND: Parental mental illness affects child health. However, less is known about the impact of different severities of maternal depression and anxiety as well as other mental health conditions. The objective of this study was to examine the impact of different severities of maternal and paternal mental health conditions on child asthma. METHODS: This nationwide, register-based cohort study included all children in Denmark born from 2000 to 2014. Exposure was parental mental health conditions categorized in three severities: minor (treated at primary care settings), moderate (all ICD-10 F-diagnoses given at psychiatric hospital) and severe (diagnoses of severe mental illness). The children were followed from their third to sixth birthday. Child asthma was identified by prescribed medication and hospital-based diagnoses. Incidence rate ratios were calculated using negative binomial regression analyses. RESULTS: The analyses included 925 288 children; 26% of the mothers and 16% of the fathers were classified with a mental health condition. Exposed children were more likely to have asthma (10.6–12.0%) compared with unexposed children (8.5–9.0%). The three severities of mental health conditions of the mother and the father increased the risk of child asthma, most evident for maternal exposure. Additive interaction between maternal mental health conditions and disadvantaged socioeconomic position was found. CONCLUSION: We found an increased risk of asthma in exposed children, highest for maternal exposure. Not only moderate and severe, but also minor mental health conditions increased the risk of child asthma. The combination of mental health condition and disadvantaged socioeconomic position for mothers revealed a relative excess risk.