This trial is testing somapacitan, a new growth hormone medicine, in children who have low levels of growth hormone. These children include those born small for their age or with conditions like Turner syndrome, Noonan syndrome, or idiopathic short stature. Somapacitan is given as an injection to help them grow better. Somapacitan is a long-acting growth hormone derivative developed for periodic administration, already approved for use in adult GH deficiency in the USA and Japan.