Low bone mineral density in the femoral neck of medieval women: A result of multiparity?

An archaeological investigation of a medieval cemetery gave us the opportun ity to investigate 49 Danish skeletons dating from 1000 to 1250 A.D. and to compare them with 298 contemporary Danes (aged 19-79 years) and assess the millennial trend in bone mineral density (BMD) in populations considered g enetically closely related. BMD and bone mineral apparent density (BMAD) of the femoral neck were measured by dual-energy X-ray absorptiometry (DEXA) and transformed into z scores. BMDzscores was significantly lower in mediev al women (-0.54 +/- 0.25, p = 0.04), whereas BMDzscores in medieval men was significantly higher (0.55 +/-_ 0.22, p = 0.02). In medieval women, BMDzsc ore tended to increase with age (r = 0.42, p = 0.07), whereas no change was seen in men (r = 0.19, not significant [n.s.]). Also, BMAD(zscore) was sig nificantly elevated in medieval men (1.00 +/- 0.28, p < 0.01), but in medie val women no difference was found (-0,28 +/- 0.21. n.s.). However, the corr elation between BMAD(zscore) and age was significant in the medieval women where it increased with advancing age (r = 0.49, p = 0.03). In conclusion, medieval women had lower BMD when compared with contemporary women, but thi s relationship was reversed in women who survived to older ages. In contras t, medieval men had significantly higher BMD as compared with contemporary men at all ages. The observed lower BMD in medieval women can be explained by the well-known selective mortality among the younger women. A high birth rate and prolonged periods of lactation are the main reasons for the obser ved increased mortality, and therefore can also very likely explain the ass ociated low BMD. The increase in the incidence of osteoporosis in modern el derly women could possibly, or partially, be explained by the survival of w omen who would have died prematurely had they lived in earlier centuries. ( C) 2001 bv Elsevier Science Inc. All rights reserved.