RESUMEN
Pregnancy and lactation-associated osteoporosis (PAO) is a rare condition characterized by the occurrence of fragility fractures, most commonly vertebral, in late pregnancy or the early postpartum period. The prevalence, etiology and pathogenesis of this osteoporosis are unknown, although there are several hypotheses attempting to explain the etiopathogenesis of pregnancy associated osteoporosis. In this paper we present two cases of young women who developed severe PAO with vertebral fractures: a 42-year-old woman with a family history of osteoporosis, and a 21-year-old woman affected with myasthenia gravis. The case 1 presented fragility fracture of D12, L2, and L3. She did not have any disease causing osteoporosis. However, she had a positive familial history for osteoporosis and during pregnancy (12th week) she had a detached placenta, so bed rest was prescribed for two months. The case 2 presented multiple vertebral fracture. She was affected by myasthenia gravis, which was diagnosed two years before pregnancy, and treated with corticosteroid. In summary, pregnancy and lactation-induced osteoporosis, although it is a rare disorder, should be kept in mind when pregnant women or women in postpartum period develop persistent back pain and it is important to monitor the patients with risk factors or secondary causes of osteoporosis.