Research in Developmental Disabilities 59 (2016) 306–317 Contents lists available at ScienceDirect Research in Developmental Disabilities High variability of individual longitudinal motor performance over five years in very preterm infants Anjo J.W.M. Janssen (PhD, PPT) a,∗ , Rob A.B. Oostendorp (PhD, MPT) b , Reinier P. Akkermans (MSc) b , Katerina Steiner (MD) c , Louis A.A. Kollée (PhD, MD) c , Maria W.G. Nijhuis-van der Sanden (PhD, PPT) a,b a Radboud University Medical Center, Amalia Children’s Hospital, Department of Rehabilitation, Pediatric Physical Therapy, Nijmegen, The Netherlands b Radboud University Medical Center, Radboud Institute for Health Sciences, Scientific Institute for Quality of Healthcare, Nijmegen, The Netherlands c Radboud University Medical Center, Amalia Children’s Hospital, Department of Pediatrics, Nijmegen, The Netherlands a r t i c l e i n f o Article history: Received 21 February 2016 Received in revised form 25 August 2016 Accepted 19 September 2016 Number of reviews completed is 3 Keywords: Premature birth Motor skills Longitudinal studies a b s t r a c t Aim: To determine longitudinal motor performance in very preterm (VPT) infants from 6 months to 5 years of age for the entire cohort of infants, according to gender and gestational age and at the individual level. Method: Single-center, prospective longitudinal study of 201 VPT infants (106 boys) without severe impairments. Outcomes: Motor performance was assessed with the Bayley Scales of Infant Development (BSID-II-MS: 6, 12, 24 months) and the Movement Assessment Battery for Children (MABC- 2-NL: 5 years). Results: At 6, 12, and 24 months and then at 5 years, 77%, 80%, 48%, and 22% of the infants, respectively, showed delayed motor performance (<−1SD). At 5 years, girls performed significantly better than boys in manual dexterity and balance. Mixed model analyses: that examined interactions between time and gender and time and gestational age, revealed no significant interactions. The variance at child level was 29%. Lin- ear mixed model analysis revealed that mean z-scores of −1.46 at 6 months of age declined significantly to −0.52 at 5 years. Individual longitudinal motor performance showed high variability. Implications: Longitudinal motor performance improved almost 1 SD over five years. How- ever, the variability of individual longitudinal motor performance hampers evaluation in clinical care and research. © 2016 Elsevier Ltd. All rights reserved. ∗ Corresponding author at: Radboudumc, Amalia Children’s Hosptital, Department of Rehabilitation, Pediatric Physical Therapy 818, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. E-mail addresses: anjo.janssen@radboudumc.nl (A.J.W.M. Janssen), rob.oostendorp@planet.nl (R.A.B. Oostendorp), reinier.akkermans@radboudumc.nl (R.P. Akkermans), Katerina.steiner@radboudumc.nl (K. Steiner), l.a.a.kollee@glazenkamp.net (L.A.A. Kollée), Ria.Nijhuis-vanderSanden@radboudumc.nl (M.W.G. Nijhuis-van der Sanden). http://dx.doi.org/10.1016/j.ridd.2016.09.017 0891-4222/© 2016 Elsevier Ltd. All rights reserved.