How long does it take for new born babies to develop kneecaps?

Read on. Depends on the wording. Newborns develop kneecaps 4 months in utero but the are all cartilage, not bone. After birth the are growth centers and bone will develop. Around 3 yrs in girls and 5 to 6 in boys they are ossified(bone). Am interesting fact. Some say that they develop into bone later as we bear more weight on the legs and need support also crawling is easier on the knees when not bone!