Three patients with osteoporosis associated to pregnancy are presented. The three patients developed multiple vertebral fractures in the third trimester of pregnancy with normal analytical and hormonal studies and diminished bone mineral density being observed. Other causes of osteoporosis were discarded. The patients were treated with sodium fluoride and calcium with a consequent increase in bone mineral density being achieved in two and stabilization in the third patient. Given the rarity of this entity, the literature concerning this disease is reviewed, with particular emphasis being placed on etiopathogenesis, treatment and evolution.