IMPORTANCE There are concerns that apparently healthy extremely preterm children face a risk of developing motor impairments, such as developmental coordination disorder. OBJECTIVE To evaluate the prevalence of developmental coordination disorder and associated comorbidities in a national cohort of apparently healthy children born at 22 to 26 gestational weeks, compared alongside term-born peers. DESIGN, SETTING, AND PARTICIPANTS This prospective, population-based cohort study included all children who were consecutively born at 22 to 26 gestational weeks in Sweden from April 1, 2004, through March 31, 2007. At 6.5 years, 441 preterm children were evaluated alongside 371 controls. A total of 275 preterm children (62.4%) and 359 term-born children (96.8%) did not have neurodevelopmental disabilities. Motor assessments were completed for 229 of 275 preterm children (83.3%) and 344 of 359 (95.8%) term-born children, who composed the final study sample. MAIN OUTCOMES AND MEASURES Developmental coordination disorder was defined as a score of the fifth percentile or lower on the Movement Assessment Battery for Children-Second Edition scale, using control group scores. Assessment tools included the Wechsler Intelligence Scale for Children-Fourth Edition, the Brown Attention-Deficit Disorder Scales, the Five to Fifteen questionnaire, and the Strengths and Difficulties questionnaire. RESULTS Of the 229 extremely preterm children and 344 term-born controls who underwent motor assessments, 115 (50.2%) and 194 (56.4%) were boys, respectively. Developmental coordination disorder was present in 85 of 229 (37.1%) preterm children and in 19 of 344 controls (5.5%) (adjusted odds ratio [OR], 7.92; 99% CI, 3.69-17.20). When preterm children with developmental coordination disorder were compared with term-born peers, the risk was increased for total behavioral problems, internalizing, externalizing, attentional problems, hyperactivity, perceptual problems, executive dysfunction, and poor social skills, with adjusted ORs varying from 2.66 (99% CI, 1.09-6.48) for time concepts to 9.06 (99% CI, 3.60-22.8) for attentional problems (all P < .01). When preterm children with and without developmental coordination disorder were compared, preterm children with developmental coordination disorder had more behavioral problems; the adjusted OR for total behavioral problems was 2.71 (99% CI, 1.15-6.37); for externalizing problems, 2.80 (99% CI, 1.10-7.12); for inattention, 3.38 (99% CI, 1.39-8.18); and for combined attention/hyperactivity problems, 3.68 (99% CI, 1.47-9.16) (all P < .01). Parents underestimated the children's motor problems and only a few of the children had received psychological care or physiotherapy. CONCLUSIONS AND RELEVANCE Children who were born extremely preterm faced a high risk for developmental coordination disorder with associated comorbidities. Our findings support the importance of a structured follow-up of motor function, behavior, and cognition.

Extremely preterm birth carries a risk of minor neurological dysfunction (MND). MND in children born extremely preterm is associated with impaired motor function and cognitive abilities, and behavioural problems. Male sex is associated with MND in children born extremely preterm.