Duration of breastfeeding as a risk factor for vertebral fractures

Among the risk factors for osteoporosis and fractures, gynecological history (fertile period, parity and breastfeeding) play an important part. Changes in calcium metabolism to enable an adequate mineral transfer to the milk have a prominent role in bone loss during breastfeeding. Data on the influence of breastfeeding in postmenopausal osteoporosis are inconsistent. The aim of the present study was to identify any association between duration of breastfeeding and vertebral fractures in postmenopausal women.

All patients underwent the following tests: bone mineral density measurements of the lumbar spine (L1-L4) and the total and femoral neck using dual-energy X-ray absorptiometry and antero-posterior and lateral radiography of the thoracic and lumbar spine to identify vertebral fractures.

The study involved 752 women with a mean age of 64.5±9.3; 23% of them reported vertebral osteoporotic fractures. The women with vertebral fractures had breastfed for longer periods (11.8±12.9 vs. 9.3±11.2months, p=0.03) and had more pregnancies (2.6±2.2 vs. 2.2±1.3, p=0.002). Breastfeeding for more than 18months was associated with a two-fold risk of developing vertebral fractures (OR 2.12, 95% CI 1.14-5.38, p=0.04), particularly in those without current or past use of drugs positively affecting bone.

Our study showed an association between long periods of breastfeeding and vertebral fractures, supporting a role for lengthy lactation as a risk factor for osteoporotic fractures after menopause. Bearing in mind all the benefits of breastfeeding, this finding suggests the importance of an adequate calcium and vitamin D intake during pregnancy and breastfeeding, with the aid of dietary supplements if necessary.