Long-Term Sequential Therapy for Pregnancy- and Lactation-Associated Osteoporosis With Multiple Vertebral Fractures: A Case Report of Over 5 Years.

Background: Pregnancy- and lactation-associated osteoporosis (PLO) is a rare condition that may cause multiple vertebral fractures during late pregnancy or the postpartum period. Evidence regarding treatment strategies remains limited, particularly regarding long-term outcomes of sequential regimens combining anabolic and antiresorptive therapies. Case Presentation: A 37-year-old woman developed low back pain 3 months postpartum and was diagnosed with PLO accompanied by multiple acute and chronic vertebral fractures. Breastfeeding was discontinued, and initial treatment with vitamin D analogs and bisphosphonate therapy was selected based on clinical and patient-specific considerations, including documented efficacy in PLO, the absence of reproductive safety concerns, and patient preferences. Despite early improvement, lumbar spine Z-score remained persistently low at -3.0, and therapy was sequentially transitioned to daily teriparatide for 2 years, romosozumab for 1 year, and denosumab for maintenance. Over 5 years and 7 months, lumbar spine and femoral neck bone mineral density increased by 53.4% and 26.1%, respectively. No new fractures occurred, and serial bone turnover markers demonstrated appropriate anabolic and antiresorptive responses at each phase of therapy. Conclusion: This case highlights a successful long-term sequential treatment strategy for PLO involving bisphosphonate, teriparatide, romosozumab, and denosumab in a patient without desire for further pregnancy, without reproductive safety constraints. The individualized sequential approach developed through patient education and shared decision-making may help achieve sustained improvements in bone mineral density and prevent refracture in patients at very high fracture risk, particularly when an anabolic-first strategy is not initially feasible.