Table 1.

Characteristics of included studies

Author, year	Country	Sample size (female)	Diagnosis	Age, Median (range)/Mean ± SD		Intervention	Interest outcome measures	Assessments timepoint
				Baseline (mon)	Gestational age (week)
Nelson (2001) [30]	America	EG: 21(14) CG: 16(5)	High risk of CP	EG: 7.72 ± 0.19 of CA CG: 7.74 ± 0.21 of CA	EG: 26.28 ± 2.24 CG: 26.75 ± 1.35	EG: EE + Standard care CG: Standard care	Motor: BSID-II Cognitive: BSID-II	12 mon of CA
Ohgi (2004) [31]	Japan	EG: 12(3) CG: 11(3)	High risk of CP	EG: 0 CG: 0	EG: 30.3 ± 3.3 CG: 30.3 ± 2.7	EG: EE CG: Standard care	Motor: BSID-II Cognitive: BSID-II	6 mon of CA
Blauw-Hospers (2011) [32]	America	EG: 21(12) CG: 25(14)	High risk of CP	3–6 of CA	EG: 29 (27–40) CG: 30 (25–39)	EG: EE CG: Standard care	Motor: AIMS Cognitive: BSID-II	6 mon of CA, 18 mon of CA
Morgan (2015) [33]	Australia	EG: 6(1) CG: 7(1)	High risk of CP	EG: 4.10 ± 0.96 of CA CG: 4.01 ± 0.91 of CA	EG: 35.50 ± 5.21 CG: 33.57 ± 7.76	EG: EE CG: Standard care	Motor: PDMS-II	after 12-week intervention
Morgan (2016) [34]	Australia	EG: 15(7) CG: 15(6)	High risk of CP	EG: 3.62 ± 1.10 of CA CG: 4.61 ± 1.17 of CA	EG: 34.27 ± 5.27 CG: 35.27 ± 5.09	EG: EE CG: Standard care	Motor: PDMS-II, GMFM-66 Cognitive: BSID-III	12 mon of CA
Dusing (2018) [35]	America	EG: 7(2) CG: 7(4)	High risk of CP	EG: 0 CG: 0	EG: 25 (24–27) CG: 26 (25–28)	EG: EE + Standard care CG: Standard care	Motor: TIMP, BSID-III Cognitive: BSID-III, EPSI	after 15-week intervention, 12 mon of CA
Holmström (2019) [36]	Sweden	EG: 19(7) CG: 20(6)	High risk of CP, motor disfunction and preterm	EG: 6.3 ± 1.62 of CA CG: 6.7 ± 1.96 of CA	EG: 33 ± 6.5 CG: 33 ± 6.95	EG: EE CG: Standard care	Motor: PDMS-II, GMFM-66, BSID-III Cognitive: BSID-III	after 35-week intervention, 24 mon of CA
Harbourne (2019) [37]	America	EG:11(N/A) CG:9(N/A)	High risk of CP and CP	15 ± 6.9	N/A	EG: EE CG: Optimal Pattern Intervention	Motor: GMFM-88 Cognitive: EPSI	after 12-week intervention
Hielkema (2020a) [38]	Netherlands	EG: 23(8) CG: 20(9)	High risk of CP	EG: 1.4 (0.1–8.6) CG: 2.5 (0.9–9.0)	EG: 32 (26–41) CG: 29 (26–41)	EG: EE CG: PT	Motor: IMP, AIMS, Bayley-II, GMFM-66, GMFM-88 Cognitive: Bayley-II	after 48-week intervention, 21 mon of CA
Hielkema (2020b) [39]	Netherlands	EG: 23(8) CG: 20(9)	High risk of CP	EG: 1.4 (0.7–2.8) CG: 2.5 (1.8–4.7)	EG: 32 (29–40) CG: 29 (27–38)	EG: EE CG: PT	NA	after 48-week intervention, 21 mon of CA
Harbourne (2021) [40]	America	EG: 55(26) CG: 57(22)	High risk of CP	EG: 10.67 ± 2.57 of CA CG: 10.93 ± 2.63 of CA	N/A	EG: EE + Standard care CG: Standard care	Motor: GMFM-88, BSID-III Cognitive: APSP, BSID-III	after 36-week intervention,
Ziegler (2021) [41]	Switzerland	EG: 8(2) CG: 8(1)	High risk of CP	EG: 1.04 (0-3.45) CG: 3.34 (0-5.06)	EG: 27 (25–30) CG: 29.5 (26–31)	EG: EE CG: Standard care	Motor: IMP, BSID-III Cognitive: BSID-III	18 mon of CA, 24 mon of CA
Cemali (2022) [42]	Turkey	EG: 17(5) CG: 17(11)	CP	EG: 14.47 ± 1.28 CG: 13.82 ± 1.55	N/A	EG: EE + PT CG: PT	Motor: AIMS	after 8-week intervention
Alberge (2023) [43]	France	EG: 63(28) CG: 59(22)	High risk of CP	EG: 8.5 (8.28–8.97) of CA CG: 8.5 (8.28–8.97) of CA	EG: 27.6 ± 1.3 CG: 27.4 ± 1.4	EG: EE CG: Standard care	Motor: BSID-III Cognitive: BSID-III	9 mon of age, 24 mon of age

EG experiment group, CG control group, CP cerebral palsy, N/A not applicable, w weeks, mon months, CA corrected age, EE environmental enrichment, PT physiotherapy, BSID-II Bayley Scales of Infant Development-Second Edition, AIMS Alberta Infant Motor Scale, PDMS-II Peabody Developmental Motor Scales- Second Edition, GMFM-66 Gross Motor Function Measure-66, BSID-III Bayley scales of infant development-Third edition, TIMP Test of Infant Motor Performance, GMFM-88 Gross Motor Function Measure-88, EPSI Early Problem Solving Indicator, IMP Infant Motor Profile, APSP Assessment of Problem Solving in Play