Table 8.

Play

Study	Age at different assessments (in months)	Total number of participants	Number of EL siblings	Number of siblings with ASD outcome	Number of siblings with TD outcome	Number of siblings with another outcomea	Topic	Assessment method	Diagnostic instruments	Difference EL-ASD vs EL-TD and/or predicts ASD diagnosis	Main findings
Christensen et al. (2010) US [54]	6, 12, 18, 36	77	58	17	29	12	Play: functional repeated play non-functional repeated play, symbolic play	Free play-assessment (based on set of toys) videotaped and coded	MSEL,VABS, parent concerns’ interview	No	At 18 m: EL-ASD had fewer novel other-directed functional play than TL EL-ASD showed greater levels of non-functional repeated play than TL (but the effect dropped out when controlling for verbal age); EL-TD showed more non-functional repeated play than TL no between-group difference in symbolic play no between-group difference in functional repeated play no difference between EL-Other, EL-TD and TL on novel functional play
Sacrey et al. (2015) Canada [19]	6, 9, 12, 15, 18, 24, 36–42	237	168	62	106	–	Play: parents’ concerns	Parent concerns’ interview	ADOS-G, ADI-R, expert clinical judgment according to DSM-IV	Yes	At 9 m: EL-ASD showed poorer play skills than EL-TD and TL according to parents’ concerns EL-TD and TL did not differ after post-hoc analysis

^aAtypical outcome: deficit in general cognition, motor functioning, language delay, Broader Autism Phenotype (BAP, social communication delay)