Changes in cortical volumetric bone mineral density and thickness, and trabecular thickness in lactating women postpartum.

• Context: Lactation is associated with decreased areal bone mineral density (aBMD). Replenishment occurs especially after ceased lactation. Changes in volumetric BMD (vBMD), microstructure and dimensional parameters are unknown and may clarify the role of lactation for skeletal health. Objective: and main outcomes: To test the hypothesis that lactation is associated with changes in aBMD, vBMD, microstructure and dimensional parameters. Design: At baseline (0.5 months after delivery) and 4, 12 and 18 months thereafter bone was assessed using dual energy x-ray absorptiometry (DXA) and high-resolution peripheral quantitative computed tomography (HR-pQCT). Participants: and setting: Eighty-one fair-skinned postpartum women and 21 controls aged 25-40 years were recruited. Completion ratio was 73%. Postpartum women were categorized depending on duration of lactation; 0-3.9, 4-8.9 and ≥9 months. Results: During the first 4 months, aBMD decreased at several sites (geometric mean±SE; -0.73±0.21% to -3.98±0.76%) in women lactating at least 4 months. During the same time, cortical vBMD at ultra-distal tibia decreased in women lactating 4-8.9 months (-0.26±0.08%) and ≥9 months (-0.49±0.10%). At 12 months postpartum, also cortical thickness (≥9 months, -2.48±0.41%) and trabecular thickness (4-8.9 months, -2.14±0.92%; ≥9 months, -2.56±1.21%) were lower than baseline. No decreases were found in women lactating less than 4 months or in controls in these parameters. At 18 months postpartum, both cortical vBMD (≥9 months, -0.77±0.17%) and trabecular thickness (4-8.9 months, -2.25±1.25%; ≥9 months, -3.21±1.41%) were lower in women with long lactation. Conclusions: Decreases in cortical vBMD, thickness, and trabecular thickness at ultra-distal tibia were found in women lactating 4 months or longer. Longer follow-up is needed to confirm whether women with extended lactation recover fully, or whether the changes could potentially lead to increased risk of fracture in later life.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Endokrinologi och diabetes (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Endocrinology and Diabetes (hsv//eng)

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