Arthrogryposis is usually estimated to affect about 1 in 3,000 live births, though some estimates are a bit lower depending on how it is counted. That works out to roughly 0.02% to 0.03% of births. It generally affects males and females about equally overall, although a few rare genetic forms can lean more toward males. It is something a person is born with, so it is mainly identified in babies and children, but of course it also affects adults because people live with it throughout life.