	Description of the final sample size
Author Year Location	Study design	Age	Preterm	Control group	Parents	Exclusion	Tools	Aim of the study
You et al. 2019 China	comparative	24 30	61	85			Gesell Development Diagnosis scale Normal Development of Social Skills from Infants to Junior High School Children scale	To compare the social competence, motor development, and cognition of late preterm infants (LPIs) with full-term infants
Benzies et al. 2017 Canada	Longitudinal	4 8 18			82	-	Ages and Stages Questionnaires	To examine longitudinal patterns of early development in Canadian children born late preterm
Ballantyne et al. 2016 Canada	Descriptive comparative	12 ± 2 weeks.	52	156		SGA Genetic disorders and relative abnormalities	Ages and Stages Questionnaires 3	The aim of this study was to compare the risk of developmental delay between late preterm and full-term Canadian born infants at age 12 months, and to determine infant and maternal factors associated with risk of delay
De Almeida Soares et al. 2015 Brazil	Intervention program		12	12				To compare the effects of a short bout of practice on reaching behavior between late preterm and full-term infants at the onset of goal-directed reaching
Bélanger et al. 2018 Canada (North Ontario)	Longitudinal	2 6 9 12 18 24	Extremely preterm 15 Very preterm 34 medium preterm 25 late preterm 23	-		Genetic disorders	Alberta Infant Motor Scale (AIMS) Early Intervention Developmental Profile (EIDP)	To provide preliminary data on the gross motor outcomes of children born prematurely and to determine the proportion and characteristics of the children who had maintained delays over the course of follow-up
Mirzakhani et al. 2020 USA	Longitudinal	24 36	42	593	635	Medium and extremely preterm infants	Ages and Stages Questionnaires 3	To examine the stability of potential delays across developmental domains at 24 and 36 months of age in late preterm (34 36 weeks) and term (≥37 weeks) children and whether the risk of delays remained high at 36 months