it is more correct to compare with the height:
Unit：CM
70=：length=42 bust=48 shoulder=17 waist=44;fits for: 60-70cm height / 6-9 Months

80=：length=47 bust=52 shoulder=18 waist=48;fits for: 70-80cm height / 9-12 Months

90=：length=52 bust=56 shoulder=19 waist=52;fits for: 80-90cm height / 18-24 Months

100=：length=57 bust=60 shoulder=21 waist=56;fits for: 90-100cm height / 3 Years Old

110= ：length=63 bust=64 shoulder=23 waist=60;fits for: 100-110cm height / 4 Years Old

120=：length=68 bust=68 shoulder=24 waist=64;fits for: 110-120cm height / 5 Years Old

130=：length=73 bust=72 shoulder=25 waist=68;fits for: 120-130cm height / 6 Years Old

140=：length=78 bust=76 shoulder=27 waist=72;fits for: 130-140cm height / 7-8 Years Old

150=：length=83 bust=80 shoulder=29 waist=76;fits for: 140-150cm height / 9-10 Years Old
Note:
1. There is 2-3% difference according to manual measurement (1 inch = 2.54 cm)
2.All measurements in cm, please note 1cm = 0.3937ch, 1 inch = 2.540cm
3. Please check carefully the figures and order the right size, don't completely depend on the "age advice". It's just for reference.