This smart ribbed jacket pattern with a matching collar includes a matching blanket.
Shown in Bernat Baby Coordinates. (Bernat.com)

Jacket
To fit chest measurement
6 mos 17 ins / 43 cm
12 mos 18” / 45.5 cm
18 mos 19” / 48 cm
2 yrs 21” / 53.5 cm

Finished chest
6 mos 21½ ins / 54.5 cm
12 mos 23½“ / 59.5 cm
18 mos 26” / 66 cm
2 yrs 28” / 71 cm

Bernat® Baby Coordinates
(140 g/5 oz)
2 colors, 2-4 balls total
6 mos (12 mos-18 mos-2 yrs)
Main Color (MC): (Blue) 1 (2-2-3) ball(s)
Contrast A: (White) 1 (1-1-1) ball
(White yarn left over from Blanket will be enough for Jacket)

Middy Collar is worked separately, then sewn on.

Construction schematics are provided in pdf download.

Ed. note: Pattern can be adapted for boys or girls (reverse buttons/buttonholes).

See coordinating blanket:
Middy Jacket and Blanket: Blanket