Table 4. Risk factors and odds ratios (ORs) for low bone mineral density (BMD).
| Variables | Low BMD | Unadjusted OR (95% CI) | Adjusted OR (95% CI)* | |
|---|---|---|---|---|
| Yes (n = 566) | No (n = 995) | |||
| BMI (kg/m2) at pre-pregnancy† | ||||
| Underweight | 132 (49.8%) | 133 (50.2%) | 3.61 (2.18–5.98)‡ | 3.21 (1.83–5.63)‡ |
| Normal | 368 (35.6%) | 665 (64.4%) | 2.01 (1.27–3.19)§ | 1.94 (1.16–3.23)∥ |
| Overweight | 41 (27.9%) | 106 (72.1%) | 1.41 (0.80–2.49) | 1.54 (0.84–2.82) |
| Obese | 25 (21.6%) | 91 (78.4%) | Ref | Ref |
| Weight gain during pregnancy | ||||
| Inadequate | 197 (44.9%) | 242 (55.1%) | 1.93 (1.46–2.57)‡ | 1.42 (1.04–1.94)∥ |
| Adequate | 246 (34.8%) | 460 (65.2%) | 1.27 (0.98–1.65) | 1.01 (0.76–1.34) |
| Excessive | 123 (29.6%) | 293 (70.4%) | Ref | Ref |
| Breastfeeding | ||||
| None or partial | 354 (33.7%) | 697 (66.3%) | Ref | Ref |
| Exclusive | 206 (40.4%) | 304 (59.6%) | 1.28 (1.01–1.62)∥ | 1.22 (0.96–1.55) |
| Maternal age, yr | ||||
| < 30 | 119 (37.7%) | 197 (62.3%) | Ref | Ref |
| 30–40 | 423 (36.5%) | 736 (63.5%) | 0.95 (0.74–1.23) | 1.06 (0.80–1.40) |
| > 40 | 24 (27.9%) | 62 (72.1%) | 0.64 (0.38–1.08) | 0.77 (0.44–1.35) |
*Adjusted ORs obtained with a logistic regression model including pre-pregnancy BMI, weight gain during pregnancy, breastfeeding status and maternal age; †Underweight, overweight, and obesity are defined as BMIs less than 18.5 kg/m2, between 23 and 24.9 kg/m2, or 25 kg/m2 or more, respectively; ‡P < 0.001; §P < 0.01; ∥P < 0.05.