We recommend buying baby bodysuits made of pure cotton but also organic cotton for the sustainability aspect. Cotton or organic cotton is very breathable, cooling in summer, warming in winter and absorbs a lot of sweat. Since we are talking about the smallest of the little ones, it is recommended for the delicate and sensitive skin to use organic cotton items, because this way you can prevent allergies already in babyhood and protect the environment at the same time. You can find a lot of interesting information about the composition and properties of the different materials here.