Table 2.

Mean scores (± SD) ^a of Bayley Scales of Infant Development (BSID-III) components by age at evaluation (n=740)

Scale	6 months of age (n=623)	12 months of age (n=552)	18 months of age (n=520)	24 months of age (n=542)
	$\overline{\mathrm{x}}\pm \mathrm{S}\mathrm{D}$	$\overline{\mathrm{x}}\pm \mathrm{S}\mathrm{D}$	$\overline{\mathrm{x}}\pm \mathrm{S}\mathrm{D}$	$\overline{\mathrm{x}}\pm \mathrm{S}\mathrm{D}$
Cognitive	97.7 ± 11.2	96.0 ± 9.6	96.6 ± 9.9	92.6 ± 8.4
Language	86.1 ± 11.1	81.4 ± 9.7	88.7 ± 10.4	89.8 ± 8.9
Motor	94.4 ± 11.3	88.6 ± 9.1	95.0 ± 9.0	94.1 ± 9.4

^aScore standardized by age at evaluation.