US: Newborn to Europe Size 49-51

US: Newborn: Corresponds to a head circumference baseline of 36 $\text{cm}$ (14.2 $\text{in}$), neck circumference of 20 $\text{cm}$, shoulder width of 18 $\text{cm}$, and age range 0–1 $\text{months}$.

Europe Size 49-51: Corresponds to a head circumference baseline of 50 $\text{cm}$ (19.7 $\text{in}$), neck circumference of 30 $\text{cm}$, shoulder width of 28 $\text{cm}$, and age range 24–48 $\text{months}$.