Lactation and Bone Loss
Studies have shown that the majority of women with pregnancy-associated osteoporosis are breastfeeding at the time of diagnosis. Duration of lactation has ranged from one week to seven months. Bone loss tends to be greatest in skeletal sites with the highest concentration of trabecular bone. Reductions in bone density by three to five percent at the lumbar spine are common.
Two physiologic occurrences may be responsible for bone loss during lactation. First, there is an increased calcium demand from maternal bone. This demand varies from woman to woman based on the amount of breast milk produced and upon the duration of lactation. Secondly, because of elevated prolactin levels, women who breastfeed tend to be in a hypoestrogenic state.
Though significant amounts of bone mineral can be lost during breastfeeding, the loss of bone tends to be transient. Studies have consistently shown significant trends in bone loss during lactation, with full recovery of bone density by six months after weaning. Kalkwarf and Specker reported women who experience an earlier resumption of menses lose less bone during lactation and recover more bone after weaning. Other studies have identified similar trends in bone loss, with full recovery of bone density by six months following the cessation of breastfeeding.