Osteoporosis in pregnancy and during lactation period is a rare clinical problem with unknown etiology and pathophysiology. Pregnancy and lactation may have significant impact on bone loss and this may result in osteoporosis and related fractures. The symptoms often occur during the first pregnancy and usually do not recur. Secondary causes of osteoporosis that may cause back pain and fractures during pregnancy should be taught in differential diagnosis. Still no guidelines exist about the accurate treatment of this rarely seen osteoporosis type, this means each case must be evaluated on an individual basis in order to decide for a treatment plan. In this case report, a 25-year-old woman, complaining of severe back pain after twenty days of giving birth, is reported.