To compare mental health at 5 years in children born extremely preterm and at term and assess associations between functional abilities and mental health within the preterm group.

In a national Norwegian cohort with gestational age (GA) 22–27 weeks or birthweight 500–999g mental health was assessed with The Strengths and Difficulties Questionnaire (SDQ), cognitive function with WPPSI-R, motor function with ABC movement test and severity of cerebral palsy (CP) with the Gross Motor Function Classification for CP (GMFCS).

Neurodevelopmental disabilities (NDD) were described as mild and moderate/severe. SDQ of the preterm children was compared with that of a non-selected reference group born at term. SDQ sub-scores ≥90th percentile were defined as a mental health problem and a total difficulty score ≥90th percentile (TDS90) as suggestive of psychiatric disorder.

Of 361 eligible preterm children parents completed SDQ for 255 (71 %). 28 (11 %) had TDS90 compared to 10 of 758 (1 %) of the reference group (OR: 8.4, 95% CI 4.0 to 17.0).

For the preterms the rate of TDS90 was higher for those with moderate/severe NDD (12/37 vs. 6/116, OR: 9. 3.0;26.0), but not for those with mild NDD (10/102 vs. 6/116) compared with those with no NDD. For preterms with no NDD TDS90 was more common than for the term reference group (6/116 vs. 10/758, OR:3.7, 1.3;10.0), and the most distinguishing features were emotional and peer problems.

Extreme prematurity is associated with increased risk of later mental health problems, particularly if they have other functional impairments.