The size 6-9 months in H&M is closest to the following:
Brand Label Weight (lbs) Height (inches)
American Apparel 12-18m 23 - 27 lbs 29 - 31 inches
BabyBoden 6-12 months 17.5 - 22 lbs 27 - 30 inches
Burt's Bees Baby (Target) 12 M 20 - 21 lbs 28 - 29.5 inches
Carters 12 months 20.5 - 24.5 lbs 28.5 - 30.5 inches
Cherokee (Target) 12 months 20 - 23 lbs 28 - 30.5 inches
Circo (Target) 12 months 20 - 23 lbs 28 - 30.5 inches
Gap 6-12 months 17 - 22 lbs 27 - 29 inches
Gymboree 12-18 months 22 - 27 lbs 29 - 31 inches
H&M 6-9 months - 29 inches
Hanna Andersson 70cm 14 - 21 lbs 26 - 30 inches
Hatley 6-12m 17 - 22 lbs 27 - 29 inches
J.Crew/ Crewcuts 6-12 months 17 - 22 lbs 29 - 30 inches
Jumping Bean (Kohl's) 12 months 20 - 23 lbs 27 - 29 inches
LLBean 6-12m 18 - 22 lbs 27 - 29 inches
Lands End 2T 27 - 29 lbs 33 - 35 inches
Marimekko 9 months/ 74 cm - 28 - 30 inches
MiniBoden 1.5 years - 32.5 inches
Old Navy 6-12 months 17 - 22 lbs 27 - 29 inches
OshKosh 12 months 20.5 - 24.5 lbs 28.5 - 30.5 inches
Petit Bateau 12M 20 - 21 lbs 29 inches
Ralph Lauren 9-12 months 19 - 22 lbs 27.5 - 29 inches
The Children's Place 0-3 months 7 - 11 lbs -
Tucker + Tate (Nordstrom) 9M 19 - 22 lbs 27.5 - 29 inches
Wal-Mart 12 months 19.5 - 22 lbs 28 - 29.5 inches
Zutano 12m 15 - 20 lbs 25 - 29 inches
childhoods 6-9 months 16 - 21 lbs 26 - 30 inches
janie and jack 9-12 months 20 - 22 lbs 27 - 29 inches
june and january 6-12 months 16 - 20 lbs 27 - 30 inches
tea 12-18 months 22 - 27 lbs 29 - 31 inches
vineyard vines 6-12 months 17 - 22 lbs 28 - 30 inches