The effect of menarcheal age on anthropometric, limb length, and bone measures in Hutterite and non-Hutterite women

The age women reach menarche may affect bone length and mass. Some studies show an earlier menarcheal age (MA) results in a shorter stature and increased body fat. We hypothesized that Hutterite women have a shorter height and limb length, but greater bone mass and areal bone mineral density (aBMD) than non-Hutterites. Results are from a secondary analysis of 344 (198 Hutterite) healthy, pre-menopausal women aged 20-40 years who participated in the South Dakota Rural Bone Health Study. Bone measures were obtained by DXA (spine, hip and total body) and pQCT (4 and 20% distal radius). MA correlated with year of birth (r = -0.10, P = 0.08) indicating a trend toward a younger MA for women born in more recent years. MA was inversely associated with current weight (r = -0.11, P < 0.05), percent body fat (r = -0.16, P < 0.01), femoral neck BMC (r = -0.18, P = 0.003), femoral neck aBMD (r = -0.21, P < 0.001), hip aBMD (r = -0.22, P < 0.001) and trabecular volumetric BMD (vBMD) (r = -0.14, P = 0.03). Hutterite women had a younger MA than non-Hutterite women (12.3 +/- 1.3 vs. 13.0 +/- 1.3 yr, P < 0.001). In final regression models controlling for diet and activity patterns, Hutterite compared to non-Hutterite women had shorter standing height (162 +/- 0.4 vs. 166 +/- 0.4 cm, P < 0.001), forearm length (258 +/- 0.8 vs. 261 +/- 0.9 mm, P = 0.04); and leg length (76 +/- 0.2 vs. 77 +/- 0.3 cm, P < 0.01) as hypothesized, but MA did not predict these outcomes. In conclusion, younger MA in Hutterite women did not explain their shorter standing height and limb lengths, but total hip aBMD was inversely associated with MA and greater in Hutterite than non-Hutterite women.