The size 2-4 months in H&M is closest to the following:
Brand Label Weight (lbs) Height (inches)
American Apparel 6-12m 16 - 22 lbs 25 - 28 inches
BabyBoden 3-6 months 13 - 17.5 lbs 23.5 - 27 inches
Burt's Bees Baby (Target) 3-6 M 12 - 16 lbs 24 - 27 inches
Carters 3 months 8 - 12.5 lbs 21.5 - 24 inches
Cherokee (Target) 6 months 12.5 - 16 lbs 24 - 25.5 inches
Circo (Target) 6 months 12.5 - 16 lbs 24 - 25.5 inches
Gap 3-6 months 12 - 17 lbs 23 - 27 inches
Gymboree 3-6 months 12 - 17 lbs 23 - 25 inches
H&M 2-4 months - 24 inches
Hanna Andersson 60cm 10 - 16 lbs 22 - 26 inches
Hatley 3-6m 12 - 17 lbs 23 - 27 inches
J.Crew/ Crewcuts 0-3 months 7 - 12 lbs 19 - 25 inches
Jumping Bean (Kohl's) 6 months 12 - 26 lbs 23 - 25 inches
LLBean 0-3m 9 - 14 lbs 22 - 25 inches
Lands End 2T 27 - 29 lbs 33 - 35 inches
Marimekko 6 months/68cm - 22 - 26 inches
MiniBoden 1.5 years - 32.5 inches
Old Navy 3-6 months 12 - 17 lbs 23 - 27 inches
OshKosh 3 months 8 - 12.5 lbs 21.5 - 24 inches
Petit Bateau 3M 10 - 12 lbs 23.5 inches
Ralph Lauren 3-6 months 10 - 14 lbs 21 - 24 inches
The Children's Place 0-3 months 7 - 11 lbs -
Tucker + Tate (Nordstrom) 3M 10 - 14 lbs 21.5 - 24 inches
Wal-Mart 6 months 12.5 - 16 lbs 23.5 - 26 inches
Zutano 6m 12 - 14 lbs 20 - 24 inches
childhoods 3-6 months 12 - 17 lbs 23 - 26 inches
janie and jack 3-6 months 12 - 17 lbs 23 - 25 inches
june and january 0-6 months 16 lbs 26 inches
tea 3-6 months 11 - 15 lbs 22 - 25 inches
vineyard vines 0-6 months 7 - 15 lbs 28 inches