Changes in bone metabolic profile associated with pregnancy or lactation

Area of Science:

• Reproductive biology
• Bone metabolism
• Maternal-fetal/infant nutrition

Background:

• Maternal calcium and nutrient transfer to fetus/infant during pregnancy/lactation induces metabolic changes.
• Many of these maternal metabolic changes remain uncharacterized.

Purpose of the Study:

• To evaluate maternal metabolic changes during pregnancy and postpartum lactation.
• To investigate the relationship between breastfeeding and postpartum bone health.

Main Methods:

• Two parallel studies were conducted: analysis of 14 clinical cases of postpartum vertebral fractures in breastfeeding mothers, and a larger study of 79 pregnant women monitoring bone metabolic status from late gestation through one month postpartum.
• Bone metabolic markers (serum TRACP5b, osteocalcin, serum PTH, urine NTX) and bone mineral density were analyzed.

Main Results:

• Bone resorption and formation markers increased postpartum. Exclusive breastfeeding was associated with higher bone-resorbing markers (serum TRACP5b, urine NTX) and parathyroid hormone (PTH) compared to formula or mixed feeding.
• No vertebral fractures were observed in the 79 women studied, irrespective of feeding method.
• Mothers with postpartum vertebral fractures exhibited significantly lower bone mineral density compared to non-fracture cases within the breastfeeding-only group.

Conclusions:

• Maternal bone metabolic status undergoes significant alterations between pregnancy and postpartum lactation.
• Low bone mineral density in a subset of exclusively breastfeeding mothers is a likely cause of postpartum vertebral fragility fractures.