Because of a special chemical produced by the placenta, there is physiologic relaxation of the joints articulating together the large bones to form the pelvis. During pregnancy this frequently causes fatigue and backache; in the last trimester it may even cause pain and difficulty in walking. A well-fitted maternity girdle should help bom the pain and the walking. Massage and heat often provide welcome relief for the tired or aching back of pregnancy. Rubbing liniment applied with the palm of the hand is particularly excellent, but one must be careful not to apply heat over freshly applied liniment lest it blister the skin. In stubborn cases of pregnancy backache special orthopedic strapping (by a physician) with adhesive tape may be required.