Osteoporosis presenting during pregnancy and lactation: wait and reassess.

Two months after her first pregnancy, a 35-year-old exclusively breastfeeding woman bent to move her baby in the car seat and experienced sudden, severe pain from five spontaneous vertebral compression fractures. Genomic screen was negative but she had mild ankylosing spondylitis previously well controlled on Etanercept. She was vegetarian with a high phytate intake. A lactation consultant had advised her to pump and discard milk between feeds, such that she believed she produced twice as much milk as her baby ingested. She presented with a lumbar spine Z score of -3.6 and a total hip Z score of -1.6. After six months post-weaning, she was treated with teriparatide (14 months intermittently over 18 months) and ultimately achieved a 50% increase in lumbar spine bone density and an 8% increase in total hip bone density. Her fragility is explained by normal lactational bone loss amplified by excessive milk production and phytate-induced impairment of intestinal calcium absorption, ankylosing spondylitis, and the bendand-lift maneuver. The marked increase in bone density resulted from the combined effects of spontaneous recovery and pharmacotherapy. Spontaneous recovery of bone mass and strength should occur during 12 months after weaning in all women, including those who have fractured.