. Author manuscript; available in PMC: 2012 Dec 13.

Published in final edited form as: J Autism Dev Disord. 2006 Dec 27;37(1):158–170. doi: 10.1007/s10803-006-0339-z

Table 1.

Early developmental milestone onsets in Infant Siblings and No-Risk Infants

Milestone	Mean onset age (and standard deviation)		Proportion of infants attaining milestone later than comparison group median
	Infant Siblings	NR infants	Infant Siblings	NR infants
Independent sitting	6.71 (.72) range 6–8 (n = 21)	6.44 (.62) range 5–7 (n = 18)	14	0^*
Reduplicated babble	8.39 (2.93) range 5–18 (n = 19)	7.06 (1.16) range 5–9 (n = 18)	55	11^*
Showing	9.05 (1.23) range 8–12 (n = 18)	8.94 (1.30) range 8–12 (n = 18)	55	28^*
Pointing	10.68 (2.27) range 8–14 (n = 17)	10.71 (1.40) range 8–14 (n = 18)	32	24
Walking	12.59 (2.24) range 10–18 (n = 17)	11.61 (1.38) range 9–14 (n = 18)	41	28
First word	14.13 (4.22) range 10–27 (n = 15)	12.35 (1.50) range 10–15 (n = 18)	56	24^*

P< .05