How does AMC develop?
At about the 5th to 6th week of pregnancy, the baby (called an embryo at this point) begins to develop joints. The joint spaces develop by 7 weeks, and the limbs can be seen moving by 8 weeks of pregnancy. This motion of joints is clearly important, as it allows the joints and structures around the joints (skin and ligaments, for example) to develop. If the joints do not move for any reason when the baby is a fetus (after 8 weeks of pregnancy) the baby will be born with joint contractures. The lack of joint motion when the baby is a fetus is known a fetal akinesia.
