Macrosomia is eveident - most probably infant born to diabetic mother. This child also looks Hypotonic / Floppy ( upper limb is in extension & the degree of flexion in the lower limb is less than what it should be ). Technically speaking, the term "floppy infant syndrome" is used to describe abnormal limpness when an infant is prone. most common genetic cause is - Down Syndrome and another well known one is - Prader-Willi syndrome. There is a long list of differentials for this condition. Those interested please refer - Hypotonia - Wikipedia, the free encyclopedia Also, there seems to be some problem with the left shoulder ( possibly a broken collar bone - from shoulder dystocia during delivery).
