Is it normal for your sternum to pop out while pregnant?

Out better than in: Although it is not normal for the sternoclavicular joint (scj) to subluxate or dislocate during pregneancy, it is certainly understandable that this joint as with most others tends to relax and become less stable during pregnancy. Anterior subluxations are more likely to avoid surgery than rare posterior subluxations of an unstable clavicle. Evaluation by orthopaedic surgeon is warranted.

Sternum: Usually, no, but all joints may get loosening and diastasis during pregnancy.