Background Epidemiological studies infancy predictors of mental disorders are scarce. Methods The study is part of a longitudinal birth‐cohort study, The Copenhagen Child Cohort CCC2000. Infant mental health and development and mother‐infant relations were assessed by community health nurses from birth to age 10 months. Data on the perinatal period were obtained from Danish National Registers. Mental health outcome at age 5–7 years was investigated in 1,585 children who were assessed by the Developmental and Well‐Being Assessment (DAWBA) and diagnosed according to the ICD‐10. Results Predictors of autism spectrum disorders were problems of oral‐motor development OR 5.02 (95% CI: 1.63–15.42) and overall development OR 4.24 (95% CI: 1.35–13.33). A deviant pattern of activity and interests were predictive of autism spectrum disorder, OR 5.34 (95% CI 1.45–19.70) and hyperkinetic disorder, OR 4.71 (95% CI: 1.28–17.39). Hyperkinetic disorder was furthermore predicted by mother‐infant relationship problems, OR 8.07 (95% CI: 2.90–22.47). The significant associations between infant developmental problems and autism spectrum disorders persisted in multiple logistic regression analyses controlled for maternal psychological problems and mother‐infant relationship problems, OR 3.21 (95% CI: 1.09–9.45). Mother‐infant relationship problems remained strongly associated to hyperkinetic disorders in the multivariate analyses controlled for child development problems and maternal psychological problems, OR 5.20 (95% CI: 1.55–17.47). No significant infancy predictors were found regarding emotional and behavioural disorders at age 5–7 years. Conclusion Predictors of autism spectrum/pervasive developmental disorders and hyperkinetic disorders at child age 5–7 years were identified between birth and child age 10 months in community health settings. The study results suggest potential areas of early preventive intervention, which have to be further explored regarding the psychometric qualities of the identification of infants at risk, and concerning methods to handle and intervene towards these children in the general child health surveillance.