Pregnancy- and lactation-associated osteoporosis (PLO) is a rare form of osteoporosis. It results in severe low back pain in the last trimester of pregnancy and in the postpartum period, decreases in height, and fragility fractures, particularly in the vertebra. The current case report presents a 32-year-old patient who presented with back and low back pain that began in the last trimester of the pregnancy and worsened at two months postpartum and who was diagnosed with pregnancy- and lactation-associated osteoporosis after exclusion of other causes; the findings are discussed in view of the current literature. PLO is a rare clinical condition causing significant disability. PLO must be kept in mind in the differential diagnosis in patients presenting with low back pain during or after pregnancy. The patients must be evaluated for the risk factors of PLO, and an appropriate therapy must be initiated.