Table 2.
Basic characteristics and bone mineral density (BMD) in women, grouped according to total duration of breast-feeding.
| Duration of breast-feeding (months) | |||||
| Never (n = 36) | 1–48 months (n = 68) | 49–96 months (n = 61) | ≥ 97 months (n = 45) | p value | |
| Age (years) | 62.6 (59.9–65.3) | 62.8 (60.8–64.8) | 64.3 (62.2–66.4) | 69.4 (67.0–71.8) | < 0.001 |
| Height (m) | 1.48 (1.46–1.50) | 1.47 (1.46–1.49) | 1.46 (1.45–1.48) | 1.46 (1.44–1.48) | 0.48 |
| Age of menopause (years) | 47.2 (45.8–48.7) | 47.6 (46.6–48.6) | 48.3 (47.2–49.3) | 47.8 (46.6–49.1) | 0.69 |
| Duration since menopause (years) | 14.6 (11.3–17.8) | 15.1 (12.9–17.3) | 15.5 (13.2–17.9) | 21.7 (19.0–24.5) | < 0.001 |
| Weight (kg) | 43.4 (40.3–46.5) | 46.1 (43.9–48.4) | 46.8 (44.5–49.2) | 45.0 (42.3–47.8) | 0.33 |
| Body mass index (BMI; kg/m2) | 19.8 (18.3–21.2) | 21.3 (20.3–22.3) | 21.8 (20.8–22.8) | 21.1 (19.1–22.4) | 0.16 |
| Total period of breast-feeding (months) | - | 31.5 (27.1–35.9) | 75.6 (71–80.2) | 136.2 (130.8–141.5) | - |
| Children (n) | 0 | 2.5 (2.2–2.8) | 4.3 (4.0–4.6) | 6.8 (6.4–7.2) | < 0.001 |
| L2–L4 vertebrae BMD (g/cm2) | 0.670 (0.628–0.711) | 0.694 (0.661–0.726) | 0.709 (0.676–0.742) | 0.666 (0.627–0.705) | 0.31 |
| Femoral neck BMD (g/cm2) | 0.613 (0.580–0.646) | 0.643 (0.620–0.668) | 0.637 (0.611–0.662) | 0.603 (0.573–0.634) | 0.15 |
Data are given as mean (95% confidence interval) of each group with a p-value for the general trend.
BMD data presented are adjusted for age.