BACKGROUND: Little is known on the motor development of moderately preterm born (MPT) children, in comparison with early preterm born (EPT) children and fullterm born (FT), for children with normal motor outcomes at school entry.
AIMS: To compare attainment rates of gross motor milestones reached between ages 1-24 months for MPT, EPT, and FT children, all with normal development upon school entry.
STUDY DESIGN: Prospective cohort study.
SUBJECTS: We included 1247 preterm (PT) children (gestational age [GA] 24.0-35.6 weeks) and 488 FT children (GA 38.0-41.6 weeks), with normal gross motor development at 4 years according to the Ages and Stages Questionnaire.
OUTCOME MEASURES: We assessed 11 gross motor milestones assessed in preventive child healthcare during six standardized visits at calendar age.
RESULTS: During the first six months, all PT categories had lower milestone attainment-rates than FTs children (differences 9-60% for PTs compared with FTs children). For all PT categories attainment rates gradually increased during toddlerhood. For PT children with higher GA, differences in attainment rates compared with FTs children were smaller and attainment rates became comparable to FT children at an earlier age. At age 24 months only attainment rates for PT children born <30 weeks GA remained lower than for FTs children (85% versus 95%, P < 0.01).
CONCLUSION: Milestone attainment rates are highly dependent on GA during the first two years. Differences between PT and FT children are larger and persist longer with lower GA. For PT children <30 weeks GA, differences still occur at 24 months. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: controlled-trials.com, ISRCTN 80622320.