Pregnancy-associated osteoporosis (PAO) is considered a rare complication of pregnancy and lactation, but the actual incidence is unknown. Pregnancy-associated osteoporosis is self-limited and usually does not recur during subsequent pregnancies, but little is known about its pathogenesis or the dynamics of bone density during the evolution and recovery phases of an acute episode. We report a case of idiopathic PAO. Follow-up included repeat measurements of bone density, which revealed a striking rate of improvement during the first 6 months after delivery (50% increase) and continuous improvement, at a diminished though still relatively high rate, during the successive year. This observation provides insight into the early stages of recovery from PAO